JP2009036589A - Target for calibration and device, method and program for supporting calibration - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate calibration of positional relation between a datum plane and an imaging unit. <P>SOLUTION: This invention relates to a target 20 for calibration provided for calibrating the direction of the optical axis of the imaging unit 15, which takes an image of an object placed on the datum plane. The target 20 for calibration has an underside that serves as a surface of contact with the data plane and two inclined plane, having a line of intersection parallel to the underside. Patterns for calibration which bring about the same pattern onto the underside by orthogonal projection are formed, respectively on the two inclined planes. As to a photographed image of the target 20 photographed by the imaging unit 15, an image analysis/processing unit 16 recognizes the two patterns for calibration, formed respectively on the two inclined planes, calculates the dimensions of the two recognized patterns for calibration and prepares the information for calibration, based on the calculated dimensions of the two patterns for calibration. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a photographing apparatus for photographing a photographing object placed on a reference plane, and a calibration target for calibrating the optical axis direction of the photographing apparatus and the calibration target using the calibration target. The present invention relates to a calibration support apparatus, a calibration support method, and a calibration support program. In particular, the present invention relates to a three-dimensional shape measuring apparatus that measures a three-dimensional shape of a measurement target by analyzing an optical pattern that is projected onto the measurement target and whose luminance changes periodically according to the position. .

As a means of obtaining 3D shape information of an object by image analysis, an optical pattern is projected onto a measurement target existing within a predetermined imaging field of view, and the deformation amount of the optical pattern deformed according to the 3D shape of the measurement target is analyzed. There is a way to do it. Typical methods include a light cutting method, a spatial code method, a fringe analysis method, and the like. These are all based on the principle of triangulation, but among them, many methods such as space fringe analysis and time fringe analysis have been proposed for the fringe analysis method, which are known as methods for obtaining high measurement accuracy.
JP 10-047924 A (published February 20, 1998) JP 09-318337 A (released on December 12, 1997)

  In the case of the above-described method, the height position is determined by the geometric positional relationship between the light projecting device that projects the optical pattern, the reference plane that is the plane on which the measurement target is placed, and the imaging device that captures the measurement target. It will affect the accuracy. This point will be described with reference to FIG.

  FIG. 31 is a diagram showing the principle of triangulation. In order to simplify the explanation, consider a case where a plane Ph having a height h from the reference plane P0 is observed by the photographing apparatus Cc having an optical axis perpendicular to the reference plane P0. In addition, the light projecting device Cp is disposed at the same height as the imaging device Cc when viewed from the reference plane P0, and projects the light pattern toward the position of the point O on the reference surface P0.

  When observing a plane Ph that is parallel to the reference plane P0 and separated by a height h, the light pattern toward the point O intersects with the point P. At this time, when viewed from the photographing device Cc, the optical pattern projected toward the reference plane P0 is observed at a position P at a distance PQ from the optical axis (Z axis). This positional deviation PQ appears as a phase difference of the optical pattern. If the phase difference can be calculated, the following equation (1)

Can calculate the height h.

  Referring to FIG. 31, it can be understood that when the optical axis of the photographing apparatus Cc is tilted, the distance PQ changes and the height h calculated from the above equation (1) also changes. Therefore, in order to accurately measure the height h, it is necessary to accurately attach the photographing apparatus Cc so that the optical axis direction of the photographing apparatus Cc is in the design direction (for example, perpendicular to the reference plane).

  Conventionally, this calibration has been performed by using an angle meter or the like so that the optical axis direction of the photographing apparatus is adjusted to the design direction. However, in this calibration method, it is necessary to use a highly accurate angle meter, which increases the burden on the user who performs calibration.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a calibration target and the like that can easily calibrate the positional relationship between a reference plane and an imaging device.

  The calibration target according to the present invention is a calibration target for calibrating the optical axis direction of the imaging apparatus with respect to an imaging apparatus that performs imaging of an imaging target placed on a reference plane, and solves the above problems. Therefore, the two inclined surfaces having a bottom surface serving as a contact surface with the reference surface and a plurality of inclined surfaces inclined with respect to the bottom surface, and whose intersecting line is parallel to the bottom surface, A calibration pattern having the same orthographic projection pattern is formed on the bottom surface.

  According to the above configuration, calibration patterns having the same pattern projected onto the bottom surface are formed on the two inclined surfaces, respectively. For this reason, for example, when the imaging device captures the calibration pattern from the normal direction of the reference plane, the dimensions of the calibration pattern included in the captured image are the same. On the other hand, when the photographing apparatus is photographed while being tilted from the normal direction of the reference plane, the dimensions of the calibration pattern included in the photographed image are different.

  Therefore, using the calibration target of the present invention, the imaging apparatus performs imaging, compares the dimensions of the calibration pattern included in the created captured image, and the imaging apparatus is provided in a predetermined direction with respect to the reference plane. It can be determined whether or not. As a result, since it is not necessary to use a highly accurate angle meter or the like, the positional relationship between the reference plane and the imaging device can be easily calibrated.

  The calibration target according to the present invention may have a plurality of sets of the two inclined surfaces. Furthermore, in the calibration target according to the present invention, the direction of at least two sets of intersecting lines may be the same with respect to the intersecting line between the two inclined surfaces in each set. In this case, the calibration pattern dimensions should be compared at least twice in one imaging operation for calibration of the tilt of the imaging device in the direction included in the reference plane and perpendicular to the direction of the intersection line. Therefore, the calibration can be performed with higher accuracy.

  In the calibration target according to the present invention, the directions of the at least two sets of intersecting lines may be different with respect to the intersecting line between the two inclined surfaces in each set. In this case, the inclination of the photographing apparatus in at least two directions included in the reference plane can be calibrated.

  By the way, since the distance from the imaging device to the two inclined surfaces of the calibration target is not constant, the imaging device is not always focused on the two inclined surfaces. Therefore, the photographing apparatus needs to adjust the focus position so that the calibration pattern on the inclined surface is in focus. For this reason, the range of adjustable focus positions is limited. In particular, in order to accurately measure the height of a minute measurement target, the depth of field that indicates a range in focus with respect to a certain focus position is narrowed, so the range of adjustable focus positions is narrowed.

  Therefore, in the calibration target according to the present invention, it is preferable that the calibration pattern is repeatedly formed on each of the two inclined surfaces. In this case, the imaging apparatus only needs to adjust the focus position so that any of a plurality of calibration patterns repeatedly formed is in focus, so that the range of adjustable focus positions can be expanded.

  In the calibration target according to the present invention, the calibration pattern may be formed on the two inclined surfaces in a range wider than the range corresponding to the depth of field of the imaging apparatus. In this case, it is possible to determine whether or not the photographing apparatus is provided in a predetermined direction with respect to the reference plane by comparing the dimensions of the in-focus area in the calibration pattern included in the photographed image. Therefore, it is not necessary to form the calibration pattern within a range corresponding to the depth of field in order to photograph an accurate calibration pattern. In order to accurately measure the size of the in-focus area, it is desirable that the calibration pattern is a fine pattern.

  Note that it is desirable that the two inclined surfaces have the same inclination angle with the bottom surface, and the intervals and / or widths of the calibration patterns are the same. In this case, the calibration target can be easily manufactured.

  A calibration support apparatus according to the present invention is a calibration support apparatus that supports calibration in the optical axis direction of the imaging apparatus with respect to an imaging apparatus that performs imaging of an imaging target placed on a reference plane, and solves the above problems. Therefore, an image acquisition unit that acquires a captured image captured by the imaging apparatus with the calibration target configured as described above, and two calibrations that are respectively formed on the two inclined surfaces from the captured image acquired by the image acquisition unit. A pattern recognizing unit for recognizing the pattern, a size calculating unit for calculating the size of the two calibration patterns recognized by the pattern recognizing unit, and a size of the two calibration patterns calculated by the size calculating unit. And calibration information creating means for creating calibration information for the calibration.

  Further, the calibration support method according to the present invention supports the calibration of the imaging apparatus in the optical axis direction by using the calibration target having the above-described configuration with respect to the imaging apparatus that performs imaging of the imaging target placed on the reference plane. A calibration support method for a calibration support apparatus, the image acquisition step for acquiring a captured image obtained by capturing the calibration target by the imaging device, in order to solve the above-described problem, and the image acquisition step A pattern recognition step for recognizing the two calibration patterns formed on the two inclined surfaces from the photographed image, and a dimension calculation step for calculating the dimensions of the two calibration patterns recognized in the pattern recognition step. And a calibration information creating step for creating calibration information for the calibration based on the dimensions of the two calibration patterns calculated in the dimension calculating step. It is characterized in that.

  Here, examples of the dimension of the calibration pattern include an interval between patterns, a width of the pattern, and a size of a region in which the pattern is focused. Note that recognizing two calibration patterns from a captured image can be performed using a known image recognition technique.

  According to the above-described configuration and method, the two calibration patterns formed on the two inclined surfaces are recognized from the captured image of the calibration target photographed by the photographing apparatus, and the two recognized calibration patterns are dimensioned. Based on the calculated dimensions of the two calibration patterns, calibration information for the calibration is created. Therefore, it is possible to support the calibration by photographing the calibration target with the photographing apparatus, and it is not necessary to use a highly accurate angle meter, etc., so that the positional relationship between the reference plane and the photographing apparatus can be easily calibrated. It can be carried out.

  In the calibration support apparatus according to the present invention, the calibration information creation means indicates that the optical axis direction of the imaging apparatus is normal when the dimensions of the two calibration patterns calculated by the dimension calculation means are equal. Calibration information may be created. In this case, the user can easily determine whether or not the optical axis direction of the photographing apparatus is normal.

  In the calibration support apparatus according to the present invention, the calibration information generating means is configured to incline the normal direction with respect to the optical axis direction of the photographing apparatus based on a ratio of the dimensions of the two calibration patterns calculated by the dimension calculating means. And the calculated inclination may be created as the configuration information. In this case, the user can determine how much the optical axis direction of the photographing apparatus is moved to be normal, and can easily perform the calibration.

  Each step in the calibration support apparatus can be executed by a computer using a calibration support program. Further, the calibration support program can be executed on an arbitrary computer by storing the calibration support program in a computer-readable recording medium.

  As described above, the image capturing apparatus captures the calibration target according to the present invention, and can perform calibration support by performing image analysis of the captured image, and uses an accurate angle meter or the like. Since there is no need, the positional relationship between the reference plane and the photographing apparatus can be easily calibrated.

[Embodiment 1]
An embodiment of the present invention will be described below with reference to FIGS. FIG. 2 is a diagram showing a schematic configuration of a three-dimensional shape measurement system (three-dimensional shape measurement apparatus) 10 according to an embodiment of the present invention.

  As shown in FIG. 2, the three-dimensional shape measurement system 10 of the present embodiment projects an optical pattern 14 from a light projecting unit 13 onto a measurement target 12 placed on a moving unit 11 and is projected onto the measurement target 12. The imaging unit (imaging device) 15 captures the obtained optical pattern 14, the image analysis / processing unit (calibration support device) 16 analyzes the shape of the captured optical pattern 14, and this is measured by the moving unit 11. It is an apparatus that measures the three-dimensional shape of the entire measurement object 12 by moving and repeating. Examples of the three-dimensional shape to be measured include the depth of the concave portion provided on the surface of the measurement object 12, the height of the convex portion, and their positions. Although the usage of the three-dimensional shape measurement system 10 is not particularly limited, it can be applied to, for example, an apparatus for inspecting a mounting board.

  In general, in a measurement system, various calibrations are performed in order to perform accurate measurement. In the three-dimensional shape measurement system 10 of the present embodiment, the positional relationship between the moving unit 11 and the imaging unit 15 is calibrated. More specifically, the imaging unit 15 is adjusted so that the optical axis direction of the imaging unit 15 is perpendicular to the upper surface of the moving unit 11, that is, the reference plane P0 on which the measurement target 12 is placed.

  FIG. 1 shows how the positional relationship between the reference plane P0 and the imaging unit 15 is calibrated in the three-dimensional shape measurement system 10. Since other calibrations are the same as those in the prior art, the description thereof is omitted in the present application.

  The three-dimensional shape measurement system 10 shown in FIG. 1 is different from the three-dimensional shape measurement system 10 shown in FIG. 2 in that a calibration target 20 is provided on the moving unit 11 instead of the measurement target 12. . The calibration target 20 of the present embodiment is for calibrating the imaging unit 15 in the optical axis direction. In the following, the case of performing calibration as shown in FIG. 1 is referred to as “calibration mode”, and the case of measuring a three-dimensional shape as shown in FIG. 2 is referred to as “measurement mode”.

  FIG. 3 shows the appearance of the calibration target 20. As illustrated, the calibration target 20 has a bottom surface 21 and a ridge line 22 parallel to the bottom surface, and has inclined surfaces 23 and 24 on both sides of the ridge line. The bottom surface 21 is a surface in contact with the upper surface (reference surface P0) of the moving unit 11. In addition, the inclined surfaces 23 and 24 are formed so that the inclination angles α, which are the angles with respect to the bottom surface 21, are equal.

  Two lines (calibration patterns) 25 and 26 are formed at equal intervals on the inclined surface 23, and two lines 27 and 28 are formed at equal intervals on the inclined surface 24. Further, the distance between the lines 25 and 26 of the inclined surface 23 is equal to the distance between the lines 27 and 28 of the inclined surface 24. Each of the lines 25 to 28 is desirably parallel to the ridge line 22, but may have at least a component in the direction of the ridge line 22. Further, the line 25 of the inclined surface 23 need not have the same height as any one of the lines 27 and 28 of the inclined surface 24. Similarly, the line 26 of the inclined surface 23 need not have the same height as either one of the lines 27 and 28 of the inclined surface 24.

  FIG. 4 shows a captured image taken by the imaging unit 15 with the calibration target 20 having the above-described configuration placed on the reference plane (the upper surface of the moving unit 11). In the following description, the imaging unit 15 is normally attached when the imaging unit 15 is attached so that the optical axis direction of the imaging unit 15 is perpendicular to the reference plane, that is, the normal direction of the reference plane. This is called “normal state”. A state in which the optical axis direction of the imaging unit 15 is tilted from the normal direction of the reference plane is referred to as a “tilted state”.

  4A shows a case where the imaging unit 15 is attached in a normal state, and FIG. 4B shows a case where the imaging unit 15 is attached in an inclined state. Referring to the figure, in the normal state, it can be understood that the distance between the lines 25 and 26 and the distance between the lines 27 and 28 in the captured image are equal. On the other hand, in the tilted state, it can be understood that the interval between the lines 25 and 26 and the interval between the lines 27 and 28 in the captured image are different.

  Therefore, by using the calibration target 20 of the present embodiment, the imaging unit 15 performs imaging, and by comparing the distance between the lines 25 and 26 and the distance between the lines 27 and 28 included in the created captured image. It can be determined whether the imaging unit 15 is in a normal state or in a tilted state. As a result, the inclination of the imaging unit 15 with respect to the reference plane can be easily calibrated.

  In addition, when the inclination angle of the inclined surface 23 or the inclined surface 24 is known, the ratio of the interval between the lines 25 and 26 and the interval between the lines 27 and 28 in the captured image is obtained, thereby imaging the normal direction of the reference surface The inclination of the unit 15 in the optical axis direction can be obtained. This point will be described with reference to FIG.

  FIG. 5 schematically shows a geometric positional relationship when the imaging unit 15 and the inclined surfaces 23 and 24 of the calibration target 20 are viewed from the front side. In the figure, the case where the inclination angles of the inclined surfaces are different is also taken into consideration. In the figure, the optical axis of the imaging unit (camera) 15 is indicated by a broken line, each inclined surface is indicated by a one-dot chain line, and the interval between the lines on each inclined surface is indicated by a solid line.

In photographing, an object (subject) in real space is considered to be projected onto the imaging surface of the camera 15 by orthogonal projection. Therefore, in the normal state, the following expressions (2) and (3) are established.
l1 = a × L1 × sin θ1 (2)
l2 = a × L2 × sin θ2 (3)
Here, L1 is an interval between lines on the first inclined surface, and l1 is a projection of the interval L1 onto the imaging surface of the camera 15 by orthogonal projection. L2 is an interval between lines on the second inclined surface, and l2 is a projection of the interval L2 onto the imaging surface by orthogonal projection. In addition, θ1 is an angle from the optical axis of the camera 15 to the first inclined surface in a normal state, and θ2 is an angle from the optical axis to the second inclined surface. Φ is an angle from the optical axis of the camera 15 in a normal state to the optical axis of the camera 15 in a tilted state. A is a photographing magnification that depends on the optical system of the camera 15 and the distance to the subject.

On the other hand, in the inclined state, the following expressions (4) and (5) hold. Here, l1 ′ is an orthogonal projection of the line interval L1 on the first inclined surface onto the imaging surface of the camera 15 in an inclined state, and l2 ′ is a line on the second inclined surface. The interval L2 is projected onto the imaging surface by orthographic projection.
l1 ′ = a × L1 × sin (θ1−φ) (4)
l2 ′ = a × L2 × sin (θ2 + φ) (5)
From the above equations (4) and (5), the inclination φ can be obtained by deleting the photographing magnification a and obtaining the intervals L1, L2, l1 ′, l2 ′ and the angles θ1, θ2.

As described above, the calibration target 20 of the present embodiment has the same inclination angle α of the inclined surfaces 23 and 24 and the same line spacing between the inclined surfaces 23 and 24. Therefore, θ1 = θ2 and L1 = L2 hold. In this case, l′ 1 / l′ 2 is the following evaluation formula from the above formulas (4) and (5).
l'1 / l'2
= Sin (θ1-φ) / sin (θ1 + φ)
= (Tan θ1-tan φ) / (tan θ1 + tan φ) (6).

When the above equation (6) is modified, the following equation is obtained. Note that k = l′ 1 / l′ 2.
tan φ = (1−k) / (1 + k) × tan θ1 (7)
From the above equation (7), if the angle θ1 is known, the inclination φ can be obtained by acquiring the interval l′ 1, l′ 2 from the captured image of the calibration target 20. Then, the optical axis of the camera 15 can be brought into a normal state by rotating the camera 15 backward by the determined inclination φ. In the case of the present embodiment, θ1 = α + 90 ° holds, and it is sufficient that the inclination angle α is known.

  When l′ 1 / l′ 2 = 1, φ = 0. Therefore, if the tilt of the camera 15 is adjusted so that the intervals l′ 1 and l′ 2 in the captured image of the calibration target 20 are equal, φ = 0, and the optical axis of the camera 15 is set to a normal state. Can do.

Next, conditions that the angle θ1 should satisfy will be described. In order to perform the calibration using the distances l ′ 1 and l ′ 2, the inclined surfaces 23 and 24 on which the lines 25 to 28 are formed on the calibration target 20 must be visible from the camera 15. Therefore, the angle θ1 and the inclination φ need to satisfy the following conditional expression.
φ <θ1 <φ + 180 ° (8).

  From the above equation (8), for example, when it is desired to measure the inclination φ within a range of ± 45 °, the angle θ1 needs to satisfy the condition of 45 ° <θ1 <135 °. Further, in the case of the calibration target 20 as shown in FIG. 3, the inclined surfaces 23 and 24 extend obliquely downward from the ridge line 22, and therefore the angle θ1 needs to satisfy the condition of 90 ° <θ1. Therefore, it is necessary to satisfy the condition of 90 ° <θ1 <135 °.

Further, the measurement sensitivity is improved as the fluctuation of the evaluation formula (6) is larger with respect to the fluctuation of the inclination φ. Therefore, the measurement sensitivity evaluation formula is as follows.
∂k / ∂φ = −2 · tan θ1 / (tan θ1 + sin φ) ^ 2 (9)
In adjusting the tilt of the camera 15, the vicinity of φ = 0 is important. Therefore, when φ = 0 is substituted into the above equation (9), the following equation is obtained.
∂k / ∂φ = −2 / tan θ1 (10).

  From this equation (10), | ∂k / ∂φ | becomes minimum when θ1 → 90 °, increases as the angle θ1 increases from 90 °, and becomes maximum when θ1 → 0 ° or 180 °. For example, when the above condition of 90 ° <θ1 <135 ° needs to be satisfied, θ1 = 135 ° is desirable.

  Next, details of the three-dimensional shape measurement system 10 will be described. FIG. 6 is a block diagram showing a main configuration of the three-dimensional shape measurement system 10. As shown in FIGS. 1 and 2, the three-dimensional shape measurement system 10 includes a moving unit 11, a light projecting unit 13, an imaging unit 15, and an image analysis / processing unit 16. The three-dimensional shape measurement system 10 further includes a movement controller 17 that controls the movement unit 11 and a light projection controller 18 that controls the light projection unit 13.

  As described above, the light projecting unit 13 is for projecting the optical pattern 14 onto the surface of the measurement target 12. Further, as shown in FIG. 6, the light projecting unit 13 includes a light source 31 such as a halogen lamp or a xenon lamp, a pattern generation element 32 for giving a pattern to light emitted from the light source 31, and an optical such as a macro lens. A system 33 is provided.

  The optical pattern to be projected may be any pattern, such as a sine wave, a triangular wave, or a rectangular wave, as long as it has a periodicity according to the position and can specify the phase. A sinusoidal optical pattern that contributes to improvement in resolution is used. Moreover, as the pattern generation element 32, what was comprised by the liquid crystal element, the thing which processed glass or a film, etc. can be used.

  As described above, the imaging unit 15 reads the measurement target 12 onto which the optical pattern 14 is projected, and acquires the image. Further, as shown in FIG. 6, the imaging unit 15 includes one line sensor 34 and an optical system 35 such as a macro lens.

  The moving unit 11 is for horizontally moving the measurement object 12 in the main scanning direction (longitudinal direction) of the line sensor 34 and in a direction perpendicular to the main scanning direction (hereinafter referred to as “sub-scanning direction”). Further, as shown in FIG. 6, the moving unit 11 includes a moving table 41 for placing the measurement object 12, a servo motor 42 for driving the moving table 41, a linear scaler 43 for detecting the position of the moving table 41, and the like. I have.

  It is possible to measure the three-dimensional shape of the entire measurement target 12 by sequentially capturing images with the line sensor 34 while moving the measurement target 12 in the sub-scanning direction by the moving unit 11. If the measurement target 12 is wider in the main scanning direction than the imaging range of the line sensor 34, the moving unit 11 may move the measurement target 12 in the main scanning direction and sequentially capture images with the line sensor 34.

  The image analysis / processing unit 16 analyzes the image of the calibration target 20 imaged by the imaging unit 15 in the calibration mode, and calculates the inclination φ of the optical axis of the imaging unit 15. By presenting the calculated inclination φ to the user, the user can calibrate the optical axis of the imaging unit 15. In the case where a rotation driving device that rotationally drives the imaging unit 15 based on an instruction from the outside is provided, the optical axis of the imaging unit 15 is changed by transmitting an instruction based on the calculated inclination φ to the rotation driving device. It can be automatically calibrated.

  Further, in the measurement mode, the image analysis / processing unit 16 analyzes the optical pattern 14 included in the image captured by the imaging unit 15 by the fringe analysis method, calculates the three-dimensional shape of the measurement target 12, and moves the movement controller. 17 and various instructions are given to the light projection controller 18. Further, as shown in FIG. 6, the image analysis / processing unit 16 includes a capture board (image acquisition means) 44 that captures an image from the imaging unit 15 as digital data, a control unit 45 that performs various controls, and various types of information. Is stored.

  In the present embodiment, the moving unit 11 is configured to move the measurement target 12. However, instead of moving the measurement target 12, the light projecting unit 13 and the imaging unit 15 are moved in the sub-scanning direction, and further in the main scanning. It is good also as a structure moved to a direction. That is, the moving unit 11 only needs to move the measurement target 12 relative to the light projecting unit 13 and the imaging unit 15.

  Although the geometric positional relationship of each part provided in such a three-dimensional shape measurement system 10 will be described below using an example, the present invention is not limited to this.

  In the three-dimensional shape measurement system 10 of the present embodiment, the line sensor 34 of the imaging unit 15 is installed so that the main scanning direction is parallel to the placement surface (reference surface) of the moving table 41. By making the main scanning direction of the line sensor 34 parallel to the placement surface of the moving table 41, the upper surface of the measurement object 12 can be imaged at a uniform magnification. Further, since the main scanning direction and the sub-scanning direction of the line sensor 34 are perpendicular to each other, a right-angle portion is captured as a right-angle portion in a two-dimensional image composed of a plurality of line images photographed while being conveyed.

  The light projecting unit 13 is installed such that its optical axis has a predetermined angle with respect to the optical axis of the imaging unit 15. Thereby, although details will be described later, the height of the measurement target 12 can be calculated based on the shift of the optical pattern projected onto the measurement target 12. The geometric arrangement of the imaging unit 15 and the light projecting unit 13 may be measured in advance at the time of installation or may be calculated by calibration.

  The operation of the three-dimensional shape measurement system 10 will be described as follows. First, various devices are calibrated. In particular, in the present embodiment, the calibration target 20 is placed on the moving table 41, the imaging unit 15 photographs the placed calibration target 20, and the image of the photographed calibration target 20 is subjected to image analysis / processing. The unit 16 analyzes and calculates the inclination φ of the optical axis of the imaging unit 15 to calibrate the optical axis of the imaging unit 15.

  After completion of various calibrations, the three-dimensional shape of the measurement object 12 is measured. First, the servo motor 42 of the moving unit 11 sets the moving table 41 at the initial setting position according to a command from the image analysis / processing unit 16 via the movement controller 17. This initial setting position determines the imaging start position in the sub-scanning direction when the imaging unit 15 images the measurement target 12, and the imaging area of the imaging unit 15 is placed on the moving table 41 of the moving unit 11. It is preferable that the measurement object 12 be positioned at the end in the sub-scanning direction.

  Then, the light projecting unit 13 projects an optical pattern onto the measurement target 12. The imaging unit 15 scans the measurement target 12 on which the optical pattern is projected, and acquires an image of the measurement target 12. The image acquired by the imaging unit 15 is transmitted to the image analysis / processing unit 16 and converted into digital data by the capture board 44 of the image analysis / processing unit 16. Then, the control unit 45 of the image analysis / processing unit 16 analyzes the optical pattern, whereby the height information of the measurement target 12 is calculated.

  Here, in the three-dimensional shape measurement system 10 of the present embodiment, the spatial fringe analysis method is used when analyzing the optical pattern in the image. Thereby, from one line image acquired by one line sensor 34 included in the imaging unit 15 once scanned, the measurement target 12 at each position in the scanning region (imaging region) of the imaging unit 15 is obtained. The height can be determined. Details of the spatial fringe analysis method will be described later.

  The moving unit 11 moves the measurement object 12 by a predetermined distance in the sub-scanning direction under the control of the image analysis / processing unit 16. Thereby, the imaging region of the imaging unit 15 in the measurement target 12 and the light pattern 14 projected by the light projecting unit 13 are shifted in the sub-scanning direction by a predetermined distance. Thereafter, the imaging unit 15 scans the measurement object 12 again to acquire a line image. The line image obtained here includes an area of the measurement object 12 that is shifted in the sub-scanning direction by a predetermined distance from the previous scanning area. The obtained image is similarly transmitted to the image analysis / processing unit 16, and three-dimensional information at each position in the new scanning region is obtained.

  As described above, the movement unit 11 moves the measurement object 12 again by a predetermined distance, the imaging unit 15 images the measurement object 12, and the image analysis / processing unit 16 repeats the process of analyzing the line image, thereby measuring. The overall three-dimensional shape of the object 12 is measured.

  Of the three-dimensional shape information of the measurement target 12, the length information of the line sensor 34 in the main scanning direction and the length information in the sub scanning direction is measured by a known method. More specifically, the length information of the measurement target 12 in the main scanning direction is calculated based on the length of the measurement target captured in the line image in the main scanning direction. On the other hand, the length information of the measurement target 12 in the sub-scanning direction is calculated based on the moving speed of the moving unit 11. Thus, the three-dimensional shape information of the measurement target 12 can be obtained by obtaining the length information and the height information of the measurement target 12 in the main scanning direction and the sub-scanning direction.

  Note that the predetermined distance is preferably equal to the length of the imaging region of the imaging unit 15 in the sub-scanning direction. Thereby, it can measure rapidly, without leaking the whole area | region of the measuring object 12 by said process.

  Further, imaging at predetermined distances can be realized by causing the imaging unit 15 to capture images at regular intervals while moving the moving table 41 at a constant speed. In this case, the movement controller 17 transmits an imaging drive signal to the imaging unit 15 via the capture board 44 at regular intervals of, for example, several KHz order. The imaging unit 15 acquires an image of the measurement target 12 onto which the optical pattern is projected using this drive signal as a trigger. On the other hand, the movement controller 17 also transmits the same conveyance drive signal at regular intervals to the movement unit 11. The servo motor 42 of the moving unit 11 drives the moving table 41 at a constant speed using this transport drive signal as a trigger. Thereby, the measurement object 12 can be imaged for each predetermined region.

  Moreover, you may utilize the linear scaler 43 for the imaging for every predetermined distance. In this case, as shown in FIG. 6, the linear scaler 43 is provided in the movement unit 11 and transmits a signal to the movement controller 17 every time the movement table 41 is moved by a predetermined distance. And the movement controller 17 will transmit an imaging drive signal with respect to the line sensor 34 of the imaging unit 15, if this signal is received. Thereby, it becomes possible to accurately perform imaging at every predetermined distance without being affected by unevenness in the conveyance speed of the moving unit 11, and as a result, the accuracy of three-dimensional measurement is improved.

  Now, advantages of such a three-dimensional shape measuring apparatus will be described. In the present embodiment, the line sensor 34 is used as a reading sensor included in the imaging unit 15. For example, when the line sensor 34 having 10,000 pixels in the main scanning direction is used, a measurement target having a length of 100 mm in the main scanning direction can be imaged with a resolution of about 10 μm. On the other hand, for example, when an area camera having 640 pixels in the horizontal direction is used, a measurement target having a horizontal length of 100 mm can be imaged only with a resolution of about 150 μm.

  In order for the area camera to capture an image with the same resolution as the line sensor 34, it is necessary to perform at least 12 sets of processing steps such as moving by a predetermined distance in the main scanning direction and capturing the image. In this case, it takes a lot of time to move the imaging unit 15 in the main scanning direction and capture the image.

  On the other hand, in the three-dimensional shape measuring apparatus of the present embodiment, by using the line sensor 34, it is possible to perform high-speed imaging with high resolution on the measurement object 12.

  Furthermore, in the present embodiment, each line image read by the imaging unit 15 is analyzed by a spatial fringe analysis method. In the spatial fringe analysis method, the phase shift of the optical pattern can be calculated from one line image, and three-dimensional information can be calculated from this phase shift. Therefore, since the total number of scans required for the measurement object 12 is only one, the number of line sensors can be limited to one. Thereby, compared with the structure which installs a some line sensor in parallel, it comes to be able to install a line sensor easily. In addition, it is possible to perform measurement at high speed as compared with a configuration in which an operation is performed a plurality of times with one line sensor.

  Furthermore, since the height can be measured based on only one line image acquired by one scan, it is possible to measure a three-dimensional shape simultaneously with the scan. As a result, for example, when inspecting a substrate, when any manufacturing defect is found on the substrate to be measured, the measurement can be interrupted immediately without repeating the imaging process until the end. Inspection can also be speeded up.

  Next, details of image analysis by the image analysis / processing unit 16 will be described. FIG. 7 shows a main configuration of the image analysis / processing unit 16. As shown in FIG. 6, the image analysis / processing unit 16 includes a capture board 44, a control unit 45, and a storage unit 46. Further, the image analysis / processing unit 16 includes an input / setting unit 47 and an output unit 48.

  The input / setting unit 47 accepts various inputs such as an instruction input, information input, and setting input from the user, and includes, for example, a key input device such as a keyboard and buttons, and a pointing device such as a mouse. In addition to the input / setting unit 47 or instead of the input / setting unit 47, a scanner device for reading printed information, a receiving device for receiving signals via a wireless or wired transmission medium, an external device or a device in its own device The above-described various inputs from the outside may be received using a playback device that plays back data recorded on the recording medium.

  The output unit 48 outputs information based on an instruction from the control unit 45. Examples of devices constituting the output unit 48 include display devices such as LCD (Liquid Crystal Display), PDP (Plasma Display Panel), and CRT (Cathode Ray Tube), and print output devices that print information on a print medium such as paper. And a transmission device that transmits a signal via the transmission medium and a recording device that records data on the recording medium.

  Next, details of the control unit 45 and the storage unit 46 of the image analysis / processing unit 16 will be described. The control unit 45 includes a calibration processing unit 51 that performs calibration processing and a measurement processing unit 71 that performs measurement processing. Each of these units is realized by causing a CPU (Central Processing Unit) to execute various control programs. Alternatively, it may be realized by a DSP (Digital Signal Processor), FPGA (Field Programmable Gate Array) or the like not shown. Details of the measurement processing unit 71 will be described later.

  The storage unit 46 is realized by one or a combination of a random access memory (RAM), a read only memory (ROM), and an external storage device. The storage unit 46 includes a set value storage unit 61. The configuration related to the measurement processing unit 71 will be described later.

  The calibration processing unit 51 includes a set value acquisition unit 52, a line recognition unit (image acquisition unit, pattern recognition unit) 53, an interval calculation unit (dimension calculation unit) 54, and an inclination calculation unit (calibration information creation unit) 55. Yes.

  The setting value acquisition unit 52 acquires the setting value input via the input / setting unit 47. The set value acquisition unit 52 stores the acquired set value in the set value storage unit 61. In the present embodiment, the set value acquisition unit 52 acquires the angle θ1 or the tilt angle α from the optical axis of the imaging unit 15 in the normal state to the inclined surfaces 23 and 24 of the calibration target 20, and stores the set value. Store in the unit 61.

  The line recognizing unit 53 acquires a captured image of the calibration target 20 captured by the imaging unit 15 via the capture board 44, and uses a known image recognition technique from the acquired captured image to detect the calibration target 20. The image areas of the lines 25 to 28 on the inclined surfaces 23 and 24 are identified. The line recognition unit 53 transmits information on the recognized image areas of the lines 25 to 28 to the interval calculation unit 54.

  Based on the information of the image areas of the lines 25 to 28 received from the line recognition unit 53, the interval calculation unit 54 is the interval between the lines on the inclined surfaces 23 and 24, that is, the interval between the lines 25 and 26 on the image. And the interval between the lines 27 and 28 on the image. The interval calculation unit 54 transmits the calculated interval information to the inclination calculation unit 55.

  The inclination calculation unit 55 calculates the inclination φ using the above equation (7) based on the interval information received from the interval calculation unit 54 and the angle θ1 or the inclination angle α read from the set value storage unit 61. To do. The inclination calculation unit 55 outputs the calculated inclination φ to the outside via the output unit 48.

  Next, details of three-dimensional shape measurement by image analysis in the measurement processing unit 71 will be described. First, the principle of the image analysis method of this embodiment will be described.

  The measurement processing unit 71 analyzes the line image of the measurement target 12 onto which the optical pattern is projected based on the spatial fringe analysis method. The spatial fringe analysis method is based on the principle of triangulation as described above. Since the principle of triangulation has been described above with reference to FIG. 31, the fringe analysis method and the spatial fringe analysis method will be described in turn below.

  First, the fringe analysis method will be described. In the present embodiment, a sinusoidal optical pattern is used as the optical pattern projected onto the measurement object 12. The sinusoidal light pattern refers to a pattern having gradation in which luminance is expressed by a sine function. In other words, an optical pattern in which the relationship between position and luminance is expressed by a sine function is called a sine wave optical pattern. An example of a sinusoidal optical pattern is shown in FIG.

  When such an optical pattern is projected onto the measurement object 12 as shown in FIGS. 10A and 10B, the projected optical pattern is observed from the top surface as shown in FIG. That is, the light pattern projected from the oblique direction is distorted at the convex portion having the height. When the measurement target 12 on which the optical pattern is projected in this way is scanned by the line sensor 34 of the imaging unit 15, the relationship between the scanning position and the luminance is as shown in FIG.

  As shown in the upper part of FIG. 11B, the luminance of the light pattern projected on the reference surface having no convex portion always changes at a constant cycle. On the other hand, as shown in the lower part of FIG. 11B, the light pattern projected on the convex part changes in the luminance cycle due to the inclination of the convex part. As a result, the optical pattern projected on the reference plane On the other hand, a phase shift occurs. Therefore, the phase of the optical pattern in a pixel at a certain position included in the image (line image) actually projected by projecting the optical pattern on the measurement object 12, and the phase of the same pixel when the optical pattern is projected on the reference plane If the difference from (reference phase) is obtained, the height of the measurement object 12 at the position corresponding to the pixel can be obtained based on the principle of triangulation.

  In calculating the phase difference, the reference phase can be obtained in advance by projecting an optical pattern on the reference plane and taking an image. On the other hand, there are roughly two methods for obtaining the phase of the optical pattern in the pixels at each position included in the image (line image) actually captured by projecting the optical pattern onto the measurement target. The difference between the spatial fringe analysis method and the time fringe analysis method lies in how to obtain this phase.

  As shown in FIG. 11B, in the sine function, there are two phases that give a certain displacement within one period. For example, in the function represented by y = sin θ, there are two phases θ that give displacement y = 0, 0 and π. There are two phases θ that give displacement y = ½, π / 6 and 5π / 6. For this reason, in the captured image, the phase of the optical pattern in the pixel cannot be obtained from only the luminance value of the single pixel (corresponding to the displacement of the sine function).

  Here, in the time fringe analysis method which is a conventionally used technique, an optical pattern whose phase is shifted by a predetermined amount is projected onto the measurement target, the measurement target is imaged again, and the two images are analyzed to analyze the phase. Is determined as one. That is, based on the luminance of a certain pixel in the first captured image, the phase of the optical pattern in that pixel is narrowed down to two, and on the basis of the luminance of that pixel in the next captured image, the phase of the optical pattern is set to 1. Specific. Therefore, it can be seen that when using the time stripe analysis method, the measurement object must be imaged at least twice even if the reflection characteristics of the measurement object are strictly uniform.

  On the other hand, in the spatial fringe analysis method, the phase at the target pixel is calculated based on the luminance of the pixel whose phase is to be obtained (hereinafter referred to as “target pixel”) and the surrounding pixels. For example, in the above example, there are two phases θ that give the displacement y = 0, 0 and π. Here, the luminance of the surrounding pixels differs between the case where the phase of the pixel of interest is 0 and the case of π. become. If the phase of the pixel of interest is 0, for example, the luminance value of the peripheral pixel existing on the side slightly smaller in phase than the pixel of interest is smaller than the luminance value of the pixel of interest. On the other hand, when the phase of the pixel of interest is π, the luminance value of the peripheral pixel existing on the side slightly smaller in phase than the pixel of interest is larger than the luminance value of the pixel of interest. Therefore, the phase of the optical pattern can be determined as one based on the pixels in the vicinity of the target pixel. Thus, the feature of the spatial fringe analysis method is to determine the phase of the target pixel based on the luminance value of the pixel existing in the vicinity of the target pixel.

  Specific processing steps of the spatial fringe analysis method used in the three-dimensional shape measurement system 10 of the present embodiment will be described in detail below, but the present invention is not limited to this, and is based on the principle of the fringe analysis method described above. Any thing can be used.

  In the present embodiment, a phase-shifted light pattern obtained by shifting the light pattern by 90 ° is virtually created from the captured line image. Here, the projected optical pattern is expressed by the following equation (11).

Then, the phase-shifting optical pattern obtained by shifting the optical pattern by 90 ° is expressed by the following equation (12).

It is expressed. Therefore, the phase φ (x) of the pixel at the position x is expressed by the following equation (13)

Can be obtained.

  Here, the value of I (x) is the luminance value of the pixel at the position x in the main scanning direction. On the other hand, the Hilbert transform is used to calculate the value of I ^ (x) (hereinafter I (x) with a hat is described in this way for convenience). That is, the luminance value I ^ (x) at the position x by the phase-shifting light pattern is expressed by the following equation (14).

It is represented by Here, since the luminance data that can be acquired is data for each pixel, that is, discrete data, the above equation (14) is changed to the following equation (15).

It approximates as follows. By this equation (15), the value of I ^ (x) can be obtained.

As described above, if the luminance value I (x) is obtained, the value of I ^ (x) can be obtained from the above equation (15), and the phase φ (x) can be obtained from the above equation (13). Then, based on the phase difference Δφ (x) between the obtained phase φ (x) and the phase φ ₀ (x) on the reference plane, the height z at the position x can be calculated based on the above-described triangulation principle. it can.

  Specifically, the height z is calculated as a distance from the reference plane, and the following equation (16)

Can be obtained. In the above equation (16), A (x, z) and B (x, z) depend on the geometrical arrangement such as the pattern period, the distance from the camera to the reference plane, and the projection angle of the pattern. This is a function determined for each pixel. However, since these functions are functions of the unknown number z, it is difficult to calculate an exact form. Therefore, in this embodiment, a calibration target with a known height is observed in advance, and the values of A (x, z) and B (x, z) are calculated for each pixel x, and are used to calculate a straight line. The function form of z is estimated by approximation or spline function approximation.

  Next, the configuration of the measurement processing unit 71 will be described. FIG. 12 shows the main configuration of the image analysis / processing unit 16, particularly the main configuration of the measurement processing unit 71. The measurement processing unit 71 includes a background removal unit 72, a luminance acquisition unit 73, a Hilbert conversion unit 74, a phase calculation unit 75, a phase difference calculation unit 76, and a height calculation unit 77. The storage unit 46 of the image analysis / processing unit 16 includes an arctangent DB (Database) 62, a reference phase DB 63, and a three-dimensional shape DB 64.

The arc tangent DB 62 is a database indicating the correspondence between y and x in a function represented by y = tan ⁻¹ x, and stores the value of x and the value of tan ⁻¹ x in advance. Thus, the arctangent value y can be searched based on the value of x.

The reference phase DB 63 is a database that stores in advance the phase of an optical pattern (hereinafter referred to as “reference phase”) in each pixel of a line image obtained by imaging a reference plane (a plane whose height is always 0) on which the optical pattern is projected, A position x in the main scanning direction of a pixel included in the line image and a reference phase φ ₀ (x) in the pixel are stored in association with each other. Thereby, based on the information on the position x of the pixel included in the line image, the reference phase φ ₀ (x) in the pixel can be searched. The reference phase DB 63 is preferably stored or updated in advance in the storage unit 46 in the calibration mode.

  The three-dimensional shape DB 64 is a database for storing three-dimensional shape information of the measurement target 12 obtained by measurement. The three-dimensional shape DB 52 is associated with x-coordinates (corresponding to the main scanning direction), y-coordinates (corresponding to the sub-scanning direction), and z-coordinates (corresponding to the height) that specify points on the surface of the measurement object 12. Stored. Thus, after the measurement is completed, the height (z coordinate) at the position can be searched based on the x coordinate and the y coordinate of the measurement target 12.

  The background removing unit 72 removes a background component from the line image acquired from the capture board 44. The background removal unit 72 transmits the line image from which the background component has been removed to the luminance acquisition unit 73 and the Hilbert conversion unit 74. Specifically, the background removing unit 72 displays the line image obtained by capturing the measurement object 12 with the light pattern projected and the measurement object 12 irradiated with light having a uniform luminance without projecting the light pattern. The captured control line image is acquired, and the luminance value of each pixel in the line image in a state in which the light pattern is projected is divided by the luminance value of the corresponding pixel of the control line image.

  In addition, when removing the background component in a line image, it is good also as a structure which scans twice in the state which the imaging unit 15 projected the optical pattern, and the state which is not projecting, and is the same as that of the imaging unit 15 A second imaging unit may be further provided, and the second imaging unit may acquire the control line image.

  In the case of performing the above two scans, it is preferable that the pattern generating element 32 provided in the light projecting unit 13 is constituted by a liquid crystal element. This makes it possible to easily switch on / off the optical pattern. Alternatively, the pattern generation element 32 having a pattern formed area and a pattern formed area on the surface of the glass or film is prepared, and the presence or absence of the pattern is switched by shifting the glass or film. Good.

  The luminance acquisition unit 73 acquires the luminance value I (x) of the pixel at the position x from the line image data from the background removal unit 72, that is, the line image data from which the background component has been removed. The luminance acquisition unit 73 transmits the acquired luminance value to the phase calculation unit 75.

  The Hilbert conversion unit 74 calculates the luminance value of the pixel based on the phase-shifted light pattern at the position x from the line image data from the background removal unit 72, that is, the line image data from which the background component has been removed, based on the equation (15) I ^ (x) is calculated. The Hilbert conversion unit 74 transmits the calculated luminance value to the phase calculation unit 75.

  The phase calculation unit 75 uses the luminance value I (x) from the luminance acquisition unit 73 and the luminance value I ^ (x) from the Hilbert conversion unit 74, and at the position x based on the above equation (13). The phase of the optical pattern is calculated. The phase calculation unit 75 transmits the calculated phase to the phase difference calculation unit 76. The phase calculation unit 75 may determine the arctangent value by referring to the arctangent DB 62 after dividing the luminance value I (x) by the luminance value I ^ (x).

The phase difference calculation unit 76 receives the phase φ (x) of the optical pattern at the position x from the phase calculation unit 75 and acquires the reference phase φ ₀ (x) of the optical pattern at the position x with reference to the reference phase DB 63. The phase difference (phase shift) Δφ (x) at the position x is calculated by subtracting the reference phase φ ₀ (x) from the phase φ (x). The phase difference calculation unit 76 transmits the calculated phase difference to the height calculation unit 77.

  The height calculator 77 calculates the height z of the measurement object 12 at the position x from the phase difference Δφ (x) from the phase difference calculator 76 based on the above equation (16). The height calculation unit 77 stores the calculated height z in the three-dimensional shape DB 64 in association with the coordinate x in the main scanning direction and the coordinate y in the sub scanning direction.

  Next, a processing operation in the three-dimensional shape measurement system 10 having the above configuration will be described. The three-dimensional shape measurement system 10 first shifts to the calibration mode and performs calibration, and then shifts to the measurement mode and measures the three-dimensional shape of the measurement object 12.

  In the calibration mode, as shown in FIG. 1, the calibration target 20 is placed on an appropriate position on the moving table 41 and calibration is performed. FIG. 8 shows processing operations performed by the image analysis / processing unit 16 in the calibration mode.

  As illustrated in FIG. 8, first, the line recognition unit 53 acquires a captured image of the calibration target 20 captured by the imaging unit 15 via the capture board 44 (step S11). Next, the line recognition unit 53 recognizes the lines 25 to 28 applied to the calibration target 20 from the acquired photographed image using a known image recognition technique, and identifies the image areas of the lines 25 to 28. (Step S12).

  Next, based on the image areas of the lines 25 to 28 identified by the line recognizing unit 53, the interval calculating unit 54 determines the interval between the lines on the inclined surfaces 23 and 24, that is, on the images of the lines 25 and 26. The interval and the interval on the image of the lines 27 and 28 are calculated (step S13). Next, the inclination calculation unit 55 calculates the inclination φ using the above equation (7) based on the interval calculated by the interval calculation unit 54 and the angle θ1 or the inclination angle α read from the set value storage unit 61. The calculated inclination φ is output to the outside via the output unit 48 (step S14). Then, the user is inquired whether or not to repeat the calibration (step S15). When the calibration is repeated, the process returns to step S11 to repeat the above operation, and when not repeated, the calibration mode is terminated.

  FIG. 13 shows image analysis processing performed by the image analysis / processing unit 16 in the measurement mode. The image analysis / processing unit 16 sequentially calculates the height from one end to the other end of the line image in which pixels are arranged in a straight line. Therefore, first, the pixel position x in the main scanning direction is set to 0 (step S21).

  Next, the image analysis / processing unit 16 acquires the phase φ (x) at the position x (step S22). Specifically, first, the luminance acquisition unit 73 acquires the luminance value I (x) of the pixel at the position x from the line image data from which the background component has been removed by the background removal unit 72. Subsequently, the Hilbert conversion unit 74 calculates the luminance value I ^ (x) of the pixel based on the phase-shifted light pattern at the position x from the line image data based on the above equation (15). Note that the luminance acquisition unit 73 may perform the processing after the Hilbert conversion unit 74 performs the processing, or the Hilbert conversion unit 74 and the luminance acquisition unit 73 may perform the processing simultaneously.

  Then, the phase calculation unit 75 calculates the above equation (1) from the luminance value I (x) at the position x acquired by the luminance acquisition unit 73 and the luminance value I ^ (x) at the position x calculated by the Hilbert conversion unit 74. Based on 13), the phase φ (x) of the optical pattern at the position x is calculated.

Next, the phase difference calculation unit 76 subtracts the reference phase φ ₀ (x) at the position x acquired with reference to the reference phase DB 63 from the phase φ (x) at the acquired position x, thereby obtaining the position x at the position x. A phase difference Δφ (x) is calculated (step S23). Next, the height calculation unit 77 calculates the height z of the measurement object 12 at the position x based on the above equation (16) from the phase difference Δφ (x) calculated by the phase difference calculation unit 76 ( Step S24). The height calculation unit 77 stores the height z calculated in this way in the three-dimensional shape DB 64 in association with the coordinate x in the main scanning direction and the coordinate y in the sub scanning direction (step S25).

  Subsequently, it is determined whether or not the position x is the end of the linear line image (step S26). Here, if the position x is the end of the line image, the image analysis process is terminated. On the other hand, if the position x is not the end of the line image, the value of x is increased by one in order to shift the position of the target pixel by one pixel in the main scanning direction (step S27). Then, the process returns to step S22.

  By repeating the processing from step S22 to step S27, height information at each position along the main scanning direction of the measurement target 12 is accumulated in the three-dimensional shape DB 64. When the image analysis process is completed, the moving unit 11 shifts the measurement target 12 in the sub-scanning direction, and then the imaging unit 15 captures the measurement target 12 again, and again based on the line image obtained by the imaging. The image analysis process described above is performed. Thereby, the height information at each position along the sub-scanning direction is sequentially accumulated in the three-dimensional shape DB 64, and finally, the three-dimensional shape information of the entire measurement target 12 is accumulated.

  When the Hilbert conversion unit 74 obtains the luminance value of the phase-shifting light pattern at the position x based on the equation (15), the value of the parameter N in the equation (15) is changed via the input / setting unit 47. Preferably it is possible. This means that the number of pixels near the target pixel used when calculating the luminance of the phase-shifted light pattern at the position x is variable. Or it can be said that the size of the filter used in the spatial fringe analysis method is made variable.

  Here, when the value of N is increased (that is, the size of the filter is increased), the phase is calculated based on more pixels, and the calculation accuracy of the finally obtained height information is improved. On the other hand, if the value of N is reduced (that is, the size of the filter is reduced), the number of calculations required for calculating I ^ (x) is reduced, and the calculation speed is improved. Further, since it is difficult for a pixel near the target pixel to include a discontinuous point of luminance such as a black point, the influence of error propagation due to the discontinuous point can be suppressed.

  In addition, the line image captured by the imaging unit 15 may be preprocessed before being transmitted to the luminance acquisition unit 73 and the Hilbert conversion unit 74. Examples of the content of the preprocessing include removal of noise included in the line image. Furthermore, after the phase calculation unit 75 calculates the phase, post-processing may be performed on the calculated phase. For example, a PLL (Phase Locked Loop) unit may be further provided between the phase calculation unit 75 and the phase difference calculation unit 76 to reduce an error due to noise.

  Note that the pre-processing described above may be performed before step S22 shown in FIG. 13, while the post-processing described above may be performed between step S22 and step S23 shown in FIG.

  As described above, the image analysis / processing unit 16 can perform calibration based on the calibration target 20 and the line image captured by the imaging unit 15, and based on the line image captured by the imaging unit 15. In addition, the three-dimensional shape of the measurement object 12 can be measured.

  Next, a modified example of the calibration target 20 of the present embodiment will be described. FIGS. 14 to 19 show modified examples of the calibration target 20, in which (a) shows an outline and (b) shows a front view and a plan view.

  FIG. 14 shows the calibration target 20 whose shape viewed from the front is M-shaped. As illustrated, the calibration target 20 may have a shape having an inclined surface inside. FIG. 15 shows the calibration target 20 having a trapezoidal shape when viewed from the front. As shown in the drawing, the calibration targets 20 do not need to have inclined surfaces intersecting each other.

  16 and 17 show the calibration target 20 in which the inclined surface is formed as a curved surface. FIG. 18 shows a calibration target 20 having inclined surfaces with different inclination angles. In these cases, the lines may be provided on the inclined surfaces so that the intervals of the lines viewed from directly above, that is, the intervals of the lines orthogonally projected onto the bottom surface are equal.

  FIG. 19 shows the calibration target 20 in which the shape seen from the front is a shape in which a plurality of triangles are arranged. In this case, since there are a plurality of combinations of the inclined surfaces, the inclination calculating unit 55 can calculate a plurality of inclinations φ when the imaging unit 15 captures the illustrated calibration target 20 once. Therefore, if the inclination calculating unit 55 outputs the calculated average value of the plurality of inclinations φ to the outside via the output unit 48, the error of the inclination φ can be reduced, so that the accuracy of the inclination φ can be improved. it can. In other words, it is not necessary for the imaging unit 15 to image the calibration target a plurality of times in order to improve the accuracy of the inclination φ.

  As described above, the calibration target 20 can have various shapes. In the present embodiment, two lines are provided on the inclined surface, and the inclination φ of the image pickup unit 15 is calibrated using the line interval. However, one thick line is provided on the inclined surface, and the line The inclination φ of the imaging unit 15 may be calibrated using the line width of. Thus, any pattern can be used as long as the width can be defined in the tilt direction.

  Next, a preferred modification of the optical pattern projected onto the measurement object 12 will be described.

  In the three-dimensional shape measurement system 10 of the present embodiment and the devices described in Patent Document 1 and Non-Patent Document 1 described above (hereinafter referred to as “conventional device”), the brightness of the optical pattern projected onto the measurement target 12 is determined by the line sensor 34. The configuration changes along the main scanning direction. Here, in the conventional apparatus, in order to capture an image in a state in which at least two types of optical patterns whose phases are shifted are projected onto the measurement target, the direction in which the pitch of the change in the luminance of the optical pattern becomes the smallest (hereinafter referred to as “the minimum pitch direction” Need to be different from the main scanning direction of the line sensor. This is because, if these two directions are matched, even if the measurement target is transported in the transport direction perpendicular to the main scanning direction of the line sensor, the optical pattern projected on the same part of the measurement target This is because the phase does not shift.

  On the other hand, in the three-dimensional shape measurement system 10 of the present embodiment, the phase of the optical pattern, and hence the position, based on only one line image obtained by imaging the measurement target 12 on which the optical pattern is projected by the line sensor 34. The phase difference can be calculated. Therefore, no problem occurs even if the minimum pitch direction of the optical pattern is made to coincide with the main scanning direction of the line sensor 34.

  Here, in the line image captured by the line sensor 34, the brightness pitch of the optical pattern is an important factor for determining the measurement accuracy in measuring the height. Specifically, the measurement accuracy improves as the pitch is reduced. In the line image captured by the line sensor 34, the light pattern has the smallest brightness pitch when the minimum pitch direction of the light pattern matches the main scanning direction of the line sensor 34. Therefore, in the three-dimensional shape measurement system 10 of the present embodiment, the minimum pitch direction of the optical pattern projected onto the measurement target 12 is parallel to (matches) the main scanning direction of the line sensor 34. preferable.

  By the way, in the conventional apparatus, since an optical pattern is imaged with a some line sensor, it is necessary to project an optical pattern with respect to each imaging area of a some line sensor. Here, when an individual dedicated projection unit is provided for each of the plurality of line sensors, there is a problem that the projected light pattern varies for each projection unit. From such a problem, it is common to use one projection unit. Here, in order to use one light projecting unit, it is necessary to project an optical pattern that can cover all the imaging regions of a plurality of line sensors.

  However, since the three-dimensional shape measurement system 10 of the present embodiment is configured to image the measurement target 12 using the single line sensor 34, the light pattern projected by the light projecting unit 13 is a single line. Only the imaging area of the sensor 34 need be covered. Therefore, in the three-dimensional shape measurement system 10 of the present embodiment, the projected optical pattern may not be spread in the two-dimensional direction as shown in FIGS.

  At this time, in order to increase the energy efficiency of the optical pattern, it is preferable that the light projecting unit 13 projects the condensed optical pattern. Specifically, as shown in FIG. 17, the light projecting unit 13 has a linear optical pattern condensed on one axis extending in the main scanning direction of the line sensor 34 (strictly speaking, a minute finite amount in the sub scanning direction). It is preferable to project the measurement object 12 on the measurement object 12. In this case, the light projecting unit 13 includes a uniaxial condensing element for condensing the optical pattern uniaxially, and the uniaxial condensing element collects the optical pattern in a linear shape extending in the main scanning direction. That's fine. This linear optical pattern is projected so as to cover the imaging region of the line sensor 34.

  Specific examples of the uniaxial condensing element include a Fresnel lens or a cylindrical lens. If these lenses are arranged between the pattern generating element 32 and the measurement target 12, it is possible to project an optical pattern condensed on one axis with respect to the measurement target 12.

  Next, a modified example of the three-dimensional shape measurement system 10 of the present embodiment will be described. In the above description, the imaging unit 15 includes only one line sensor 34. However, the present invention is not limited to this, and may include a plurality of line sensors. By providing a plurality of line sensors, luminance noise of the line sensors can be statistically removed, and the stability of three-dimensional shape measurement can be improved. Or you may make it the structure which removes noise by imaging the same part of the measuring object 12 in multiple times.

  Moreover, in this embodiment, although the three-dimensional shape measurement system 10 has a separate configuration, part or all of these configurations can be integrated. Moreover, in this embodiment, although the line image is analyzed based on the space fringe analysis method, it can also be analyzed based on the time fringe analysis method.

[Embodiment 2]
Next, another embodiment of the present invention will be described with reference to FIGS. FIG. 20 shows the appearance of the calibration target 80 used in the three-dimensional shape measurement system 10 according to this embodiment. The calibration target 80 shown in FIG. 20 differs from the calibration target 20 shown in FIG. 3 in the pattern applied to the inclined surface, and the other configurations are the same. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted.

  A calibration target 80 shown in FIG. 20 has a bottom surface 81 and a ridge line 82 parallel to the bottom surface, and inclined surfaces 83 and 84 on both sides of the ridge line, similarly to the calibration target 20 shown in FIG. . The inclined surfaces 83 and 84 are formed so that the inclination angles α, which are the angles with respect to the bottom surface 81, are equal. On the other hand, unlike the calibration target 20 shown in FIG. 3, the calibration target 80 according to the present embodiment has striped patterns repeatedly formed on the inclined surfaces 83 and 84.

  By the way, in the said embodiment, in order to measure the space | interval of a line, it is necessary for the imaging unit 15 to image | photograph without blurring a line. That is, the imaging unit 15 needs to be able to shoot with all the lines 25 to 28 in focus. In other words, the lines 25 to 28 need to be formed within the depth of field indicating the in-focus range as shown in FIG.

  However, in the case of a three-dimensional shape measurement system that measures a fine object with high resolution, the depth of field becomes narrow, so that the range of a pattern such as a line formed on the calibration target 20 is limited. .

  On the other hand, since the calibration target of the present embodiment is repeatedly formed with striped patterns, the optical axis direction of the imaging unit 15 can be calibrated if a part of the pattern is in focus. FIG. 21 shows a captured image taken by the imaging unit 15 with the calibration target 80 having the above-described configuration placed on the upper surface of the moving unit 11. (A) of the figure shows a case where the imaging unit 15 is attached in a normal state, and (b) shows a case where the imaging unit 15 is attached in an inclined state.

  Referring to FIG. 21, it can be understood that there are in-focus regions (regions indicated by arrows) on each of the inclined surfaces 83 and 84. Therefore, by comparing the pattern of the area between the inclined surfaces 83 and 84, as described above, the inclination of the imaging unit 15 with respect to the reference surface can be calibrated, and it is affected by the depth of field. No. In addition, the imaging unit 15 only needs to adjust the focus position so that any of the repeatedly formed patterns is in focus, so that the range of adjustable focus positions can be expanded.

  Furthermore, the calibration target of the present embodiment can calibrate the optical axis direction of the imaging unit 15 by using a phenomenon caused by the depth of field. Referring to FIG. 21 again, in the normal state, it can be understood that the widths (the lengths indicated by arrows) of the in-focus regions on the inclined surfaces 83 and 84 are equal. On the other hand, in the case of the tilted state, it can be understood that the widths of the in-focus regions on the inclined surfaces 83 and 84 are different. Therefore, the optical axis direction of the imaging unit 15 can be calibrated by adjusting the imaging unit 15 so that the widths of the in-focus areas on the inclined surfaces 83 and 84 are the same.

  Therefore, by using the calibration target 80 of the present embodiment, the imaging unit 15 performs imaging, and in the areas of the inclined surfaces 83 and 84 in the created captured image, the widths of the focused areas are compared with each other. It can be determined whether the imaging unit 15 is in a normal state or in a tilted state. As a result, the inclination of the imaging unit 15 with respect to the reference plane can be easily calibrated.

  In this embodiment, a striped pattern is used, but any pattern can be used as long as it is a repeated pattern.

  Next, the conditions that should be satisfied by the stripe interval will be described with reference to FIGS. FIG. 22 shows an enlarged part of the striped pattern. As shown in the figure, the line width of the white line is Ww (μm), and the line width of the black line is Bw (μm).

  The conditions to be satisfied by the stripe interval include a condition based on the camera resolution, a condition based on the lens resolving power, and a condition based on the depth of field.

First, as a condition according to the camera resolution, both the white line and the black line need to be captured by the camera 15 with one pixel or more. For this reason, when the resolution of the camera is Pw (μm / pix), the following equation must be satisfied.
Pw <Ww and Pw <Bw (17)
For example, when the resolution of the camera is 20 μm / pix, the line widths Ww · Bw of the white line and the black line need to be larger than 20 μm.

  Next, there is MTF as an index of lens resolving power. The MTF is an index that expresses how faithfully the contrast of a subject can be reproduced, and is graphed assuming stripes of various intervals (LinePair / mm). 23 and 24 show an example of the MTF.

  For example, when the spatial frequency capable of securing 70% contrast around the lens is 10 (LP / mm) or less, the line widths Ww and Bw of the white line and the black line are 1000 μm / mm from the graphs of FIGS. It is necessary that (10 × 2) = 50 μm or more.

  Therefore, the lower limit value of the line widths Ww and Bw is determined from the condition based on the camera resolution and the condition based on the lens resolving power. The striped pattern is not formed on the surface perpendicular to the optical axis of the image pickup unit 15 but on the inclined surfaces 83 and 84. Therefore, the angle θ1 between the optical axis and the inclined surfaces 83 and 84 is taken into consideration. Thus, 1 / | sin θ1 | times the above lower limit value is set.

Next, conditions according to the depth of field will be described. When the focus range is Z (μm) in the field of view of the captured image, the focus range on the inclined surfaces 83 and 84 of the calibration target 80 is | Z / cos θ1 |. It is necessary to ensure two-period fringes within this range. Therefore, it is necessary to satisfy the following formula.
(Ww + Bw) × 3 (period) × 2 (plane) <| Z / cos θ1 | (18)
For example, when Z = 1000 (μm) and θ1 = 45 °, Ww + Bw <235.7 (μm). Here, assuming that Ww = Bw, Bw <117.8 (μm), and the upper limit value of Bw is thereby set.

  Using the above conditions, the upper limit value and the lower limit value of the line widths Ww and Bw are set.

[Embodiment 3]
Next, another embodiment of the present invention will be described with reference to FIGS. FIG. 26 shows the appearance of the calibration target 90 used in the three-dimensional shape measurement system 10 according to this embodiment. Compared to the calibration target 80 shown in FIG. 20, the calibration target 90 shown in FIG. 26 has a point that the shape is a quadrangular pyramid and a point where striped patterns are formed on four inclined surfaces. Differently, other configurations are the same. In addition, the same code | symbol is attached | subjected to the structure which has the function similar to the structure demonstrated in the said embodiment, and the description is abbreviate | omitted.

  As shown in FIG. 26, the stripes formed on each inclined surface are formed in parallel to the intersection line between the inclined surface and the bottom surface. The calibration target 90 configured as described above is placed on the upper surface of the moving unit 11 and the imaging unit 15 performs imaging. With respect to the photographed image, the inclination of the imaging unit 15 in the opposite direction in the optical axis direction can be calibrated by comparing the images of the patterns of the inclined surfaces opposite to each other in the line of intersection with the bottom surface. Therefore, by using the calibration target 90 of the present embodiment, the tilt in two directions can be calibrated with respect to the optical axis direction of the imaging unit 15.

  Next, a modified example of the calibration target 90 of the present embodiment will be described. 27 to 30 show modifications of the calibration target 20. FIG. 27, FIG. 28, and FIG. 30 show an outline in (a) of each figure and a plan view in (b). FIG. 29 shows a front view and a plan view.

  FIG. 27 shows the calibration target 90 in which the shape of the quadrangular pyramid is removed from the upper surface of the rectangular parallelepiped. As illustrated, the calibration target 90 may have a shape having an inclined surface inside. FIG. 28 shows the calibration target 90 with the upper part removed from the quadrangular pyramid. As shown in the drawing, the calibration targets 90 do not need to intersect with each other.

  FIG. 29 shows a calibration target 90 in which the inclined surface is a hemispherical spherical surface. In this case, the striped pattern may be formed so that the striped pattern seen from directly above, that is, the striped pattern orthogonally projected onto the bottom surface becomes a concentric circle. When the calibration target 90 shown in the figure is used, the tilt in all directions with respect to the optical axis direction of the imaging unit 15 can be calibrated.

  FIG. 30 shows a calibration target 90 in which two calibration targets 80 shown in FIG. 20 are combined in a cross shape. As described above, various types of calibration targets 90 can be used.

  The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

  For example, in the above-described embodiment, the normal optical axis direction of the imaging unit 15 is the direction perpendicular to the reference plane. However, if the direction of the line sensor 34 is included in the reference plane, as described in Patent Document 1 In addition, the direction can be a direction inclined by a predetermined angle from the direction perpendicular to the reference plane.

  In the above embodiment, the present invention is applied to the three-dimensional shape measurement system. However, the present invention can also be applied to an image inspection apparatus for FA (Factory Automation) such as an apparatus for inspecting a mounting board. Furthermore, the present invention can be applied to any photographing system in which the camera tilt plays an important role in capturing an image and the camera tilt cannot be easily corrected.

  Finally, each functional block of the image analysis / processing unit 16, in particular the measurement processing unit 71, may be configured by hardware logic, or may be realized by software using a CPU as follows.

  In other words, the image analysis / processing unit 16 includes a CPU that executes instructions of a control program that realizes each function, a ROM that stores the program, a RAM that expands the program, a memory that stores the program and various data, and the like. A device (recording medium) is provided. The object of the present invention is a recording in which the program code (execution format program, intermediate code program, source program) of the control program of the image analysis / processing unit 16 which is software for realizing the functions described above is recorded so as to be readable by a computer. This can also be achieved by supplying a medium to the image analysis / processing unit 16 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  The image analysis / processing unit 16 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  According to the present invention, the photographing apparatus can be easily calibrated, and thus can be suitably applied to, for example, an image inspection apparatus that inspects a mounting board.

It is a figure which shows schematic structure of the three-dimensional shape measurement system which is one Embodiment of this invention, and is a figure which shows a mode that it calibrates using the calibration target. It is a figure which shows schematic structure of the said three-dimensional shape measurement system, and is a figure which shows a mode that the measurement object is measured. It is a perspective view which shows the external appearance of the said calibration target. It is a figure which shows the picked-up image of the said calibration target, (a) has shown the case where the imaging unit of the said three-dimensional shape measurement system is normal, (b) shows the case where the said imaging unit inclines. ing. It is a figure which shows typically the geometric positional relationship which looked at the said imaging unit and the inclined surface of the said calibration target from the front side. It is a block diagram which shows the principal part structure of the said three-dimensional shape measurement system. It is a block diagram which shows the principal part structure of the image analysis and processing unit in the said three-dimensional shape measurement system. It is a flowchart which shows the processing operation which the said image analysis and processing unit performs in calibration mode. It is a figure which shows an example of the optical pattern which the light projection unit in the said three-dimensional shape measurement system projects. It is a figure which shows the shape of a measuring object, (a) is a top view, (b) is a side view. When an optical pattern is projected on the measurement target, it is a diagram showing distortion of the optical pattern projected on the measurement target, (a) is a top view, and (b) is a luminance variation and a convexity on the reference plane. It is a wave form diagram which shows the brightness | luminance fluctuation | variation in a part. It is a block diagram which shows the principal part structure of the measurement process part in the said image analysis / processing unit. It is a flowchart which shows the processing operation which the said image analysis and processing unit performs in measurement mode. It is a figure which shows the outline | summary of the modification of the said calibration target, (a) is a perspective view, (b) is a front view and a top view. It is a figure which shows the outline | summary of the modification of the said calibration target, (a) is a perspective view, (b) is a front view and a top view. It is a figure which shows the outline | summary of the modification of the said calibration target, (a) is a perspective view, (b) is a front view and a top view. It is a figure which shows the outline | summary of the modification of the said calibration target, (a) is a perspective view, (b) is a front view and a top view. It is a figure which shows the outline | summary of the modification of the said calibration target, (a) is a perspective view, (b) is a front view and a top view. It is a figure which shows the outline | summary of the modification of the said calibration target, (a) is a perspective view, (b) is a front view and a top view. It is a perspective view which shows the external appearance of the calibration target utilized with the three-dimensional shape measurement system which is another embodiment of this invention. It is a figure which shows the picked-up image of the said calibration target, (a) has shown the case where the imaging unit of the said three-dimensional shape measurement system is normal, (b) shows the case where the said imaging unit inclines. ing. It is a figure which expands and shows a part of striped pattern formed in the inclined surface of the said calibration target. It is a graph which shows an example of MTF which is a parameter | index of lens resolving power. It is a graph which shows the other example of the said MTF. It is a figure for demonstrating the depth of field. It is a perspective view which shows the external appearance of the calibration target utilized with the three-dimensional shape measurement system which is other embodiment of this invention. It is a figure which shows the outline | summary of the modification of the said calibration target, (a) is a perspective view, (b) is a top view. It is a figure which shows the outline | summary of the modification of the said calibration target, (a) is a perspective view, (b) is a top view. It is the front view and top view which show the outline | summary of the modification of the said calibration target. It is a figure which shows the outline | summary of the modification of the said calibration target, (a) is a perspective view, (b) is a top view. It is a graph for demonstrating the principle of a triangulation.

Explanation of symbols

10 3D shape measurement system (3D shape measurement device)
DESCRIPTION OF SYMBOLS 11 Mobile unit 12 Measurement object 13 Light projection unit 14 Optical pattern 15 Imaging unit (imaging device)
16 Image analysis / processing unit (calibration support device)
17 Movement controller 18 Light projection controller 20/80/90 Calibration target 21/81 Bottom surface 22/82 Ridge line 23/24 Inclined surface 25-28 line (calibration pattern)
44 Capture board (image acquisition means)
45 control unit 46 storage unit 47 input / setting unit 48 output unit 51 calibration processing unit 52 set value acquisition unit 53 line recognition unit (image acquisition unit, pattern recognition unit)
54 Interval calculation unit (size calculation means)
55 Inclination calculator (calibration information creation means)
61 Setting value storage

Claims (12)

With respect to an imaging apparatus that performs imaging of an imaging target placed on a reference plane, a calibration target for calibrating the optical axis direction of the imaging apparatus,
A bottom surface serving as a contact surface with the reference surface;
A plurality of inclined surfaces inclined with respect to the bottom surface;
A calibration target, wherein calibration patterns having the same pattern orthogonally projected onto the bottom surface are formed on the two inclined surfaces whose intersecting lines are parallel to the bottom surface.   The calibration target according to claim 1, comprising a plurality of sets of the two inclined surfaces.   3. The calibration target according to claim 2, wherein at least two sets of the intersecting lines have the same direction with respect to the intersecting line of the two inclined surfaces in each set.   3. The calibration target according to claim 2, wherein the direction of the intersecting line of at least two sets is different with respect to the intersecting line of the two inclined surfaces in each set.   The calibration target according to claim 1, wherein the calibration pattern is repeatedly formed on each of the two inclined surfaces.   2. The calibration target according to claim 1, wherein the calibration pattern is formed on the two inclined surfaces in a range wider than a range corresponding to a depth of field of the imaging apparatus.   2. The calibration target according to claim 1, wherein the two inclined surfaces have the same inclination angle with the bottom surface, and the intervals and / or widths of the calibration patterns are the same. A calibration support apparatus that supports calibration in the optical axis direction of the imaging apparatus with respect to an imaging apparatus that performs imaging of an imaging target placed on a reference plane,
Image acquisition means for acquiring a photographic image obtained by photographing the calibration target according to any one of claims 1 to 7 by the photographing apparatus;
Pattern recognition means for recognizing two calibration patterns respectively formed on the two inclined surfaces from the captured image acquired by the image acquisition means;
Dimension calculation means for calculating the dimensions of the two calibration patterns recognized by the pattern recognition means;
A calibration support apparatus comprising calibration information creating means for creating calibration information for the calibration based on the dimensions of the two calibration patterns calculated by the dimension calculating means.   The calibration information creating means creates the calibration information indicating that the optical axis direction of the photographing apparatus is normal when the dimensions of the two calibration patterns calculated by the dimension calculating means are equal. The calibration support apparatus according to claim 8.   The calibration information creation means calculates an inclination from the normal direction with respect to the optical axis direction of the imaging apparatus based on a ratio of the dimensions of the two calibration patterns calculated by the dimension calculation means, and calculates the calculated inclination as the above The calibration support apparatus according to claim 8, wherein the calibration support apparatus is created as configuration information. An imaging apparatus for imaging an imaging object placed on a reference plane, using the calibration target according to any one of claims 1 to 7, to support calibration in the optical axis direction of the imaging apparatus. A calibration support method for a calibration support apparatus
An image acquisition step of acquiring a captured image obtained by capturing the calibration target by the imaging device;
A pattern recognition step for recognizing two calibration patterns respectively formed on the two inclined surfaces from the captured image acquired in the image acquisition step;
A dimension calculating step for calculating the dimensions of the two calibration patterns recognized in the pattern recognition step;
And a calibration information creating step for creating calibration information for the calibration based on the dimensions of the two calibration patterns calculated in the dimension calculating step. An imaging apparatus for imaging an imaging object placed on a reference plane, using the calibration target according to any one of claims 1 to 7, to support calibration in the optical axis direction of the imaging apparatus. A calibration support program for operating the calibration support device
An image acquisition step of acquiring a captured image obtained by capturing the calibration target by the imaging device;
A pattern recognition step for recognizing two calibration patterns respectively formed on the two inclined surfaces from the captured image acquired in the image acquisition step;
A dimension calculating step for calculating the dimensions of the two calibration patterns recognized in the pattern recognition step;
A calibration support program for causing a computer to execute a calibration information creating step for creating calibration information for the calibration based on the dimensions of the two calibration patterns calculated in the dimension calculating step.