JP2013148375A - Calibration method, calibrator and program for use in three-dimensional shape measuring apparatus, and three-dimensional shape measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily install a calibrator in a three-dimensional shape measuring apparatus using an optical cutting method, and to accomplish calibration in a simple and accurate way.SOLUTION: A three-dimensional shape measuring apparatus comprises an optical cutting sensor 100 made up of a line laser 102 that irradiates a measurement object with an optical cutting beam L and a camera 104 that picks up images of the optical cutting beam L irradiating the measurement object, and a personal computer 200 that detects the three-dimensional shape of the measurement object by an optical cutting method. A calibrator 400 installed in the irradiation range of the optical cutting beam L has a three-dimensional shape provided with a plurality of feature regions whose coordinate values in real space are known and that differ from one another in the condition of reflecting the optical cutting beam L. A calibration method has a step of so altering measurement parameters that a three-dimensional shape A of the calibrator 400 calculated by the optical cutting method and a three-dimensional shape B of the calibrator 400 calculated by subjecting the optical cutting beam L to projective transformation coincide with each other.

Description

  The present invention relates to a three-dimensional shape measurement technique for accurately measuring an object to be measured online without contact, particularly when the object to be measured is large and the calibrator is large and accurate positioning is difficult. The present invention relates to a technique for accurately calibrating a three-dimensional shape measuring apparatus.

  In shape measurement of a large structure, a linear laser beam (light cutting line L) is irradiated from a laser light source, and reflected light is imaged by an imaging unit such as a CCD camera provided at a predetermined position. An optical cutting method has been proposed in which the dimensions and three-dimensional shape of the object to be measured are calculated from the position (coordinate values) of the optical cutting line L and alignment information such as a CCD camera. According to this method, the three-dimensional shape and dimensions of the object to be measured can be measured safely and easily without contact.

  When this light cutting method is used at a manufacturing site such as a factory, the positional relationship (distance, angle) between the laser light source and the CCD camera is shifted due to changes over time due to vibrations at the manufacturing site, etc., and the measurement results include errors due to temperature changes. It may become like. In such a case, measurement accuracy and reliability are not sufficient. In order to solve such a problem, it is necessary to calibrate the three-dimensional shape measuring apparatus.

  Japanese Patent Laid-Open No. 10-122837 (Patent Document 1) discloses a calibration method for an on-line measuring apparatus for section steel. In this calibration method, a bright line obtained by irradiating a fan beam-like light beam at a predetermined angle with respect to a measurement surface of a shape steel as an object to be measured is observed from the regular reflection direction, and the shape dimension of the measurement surface is measured on the production line. In the calibration method for calibrating an on-line measuring device for shape steel that performs precision measurement in a non-contact manner, the shape and shape of the cross section are approximately the same with the same material as the object to be measured, and the accurate shape and dimensions of each part are obtained by other means. A calibration jig that is measured and known is mounted on a calibration jig mounting base and placed at a predetermined position in the space. In this state, the shape of the calibration jig is measured, and the shape of the calibration jig is measured. The measurement apparatus is calibrated on the basis of the known value and the measurement result, and the shape dimension of the shape steel as the object to be measured can be measured with higher accuracy.

  Japanese Patent No. 2623367 (Patent Document 2) discloses a calibration method for a three-dimensional shape measuring apparatus. In this calibration method, the object to be measured is irradiated with slit light, and the shape of the light cutting line L generated on the surface of the object to be measured is imaged with a camera disposed at a fixed position with respect to the light source of the slit light. In a three-dimensional shape measuring apparatus for measuring a three-dimensional shape of an object, a calibrator having a plurality of calibration points whose positions in real coordinates are known in a planar space irradiated with slit light is used with a camera. The procedure for imaging and detecting the in-screen coordinates on the imaging screen of each calibration point is repeated while moving the calibrator in the above-mentioned planar space, and from the correspondence data between the detected actual coordinates and the in-screen coordinates. A conversion table for converting in-plane coordinates into real coordinates is created and used for measurement.

Japanese Patent Laid-Open No. 10-122837 Japanese Patent No. 2623367

  However, in the calibration method disclosed in Patent Document 1, a calibration jig (calibrator, calibration target) that is the same material as the object to be measured and whose dimensions are known is mounted on the calibration jig mounting base. It must be placed at a predetermined position in real space. Even with such a gantry, it is extremely difficult to place the calibration jig at a predetermined position in space. When the object to be measured is large, it is particularly difficult because the calibration target is also enlarged.

In the first place, it is often difficult to force an operator or a worker to “install a jig such as a calibrator in an accurate position” at a site such as a factory.
Furthermore, in the calibration method disclosed in Patent Document 2, it is necessary to repeatedly capture images with a camera while moving the calibrator in a planar space in which slit light is checked. With this calibration method, calibration cannot be performed accurately in a short time.

  The present invention has been made in view of the above-mentioned problems, and in a three-dimensional shape measuring apparatus using a light cutting method, a calibrator can be easily installed and calibrated easily and accurately. It is an object of the present invention to provide a calibration method, a calibrator, a program, and a three-dimensional shape measuring apparatus used in the original shape measuring apparatus.

In order to solve the above problems, the calibration method used in the three-dimensional shape measuring apparatus according to the present invention employs the following technical means.
That is, a calibration method according to an aspect of the present invention includes an irradiation unit that irradiates an object to be measured with an optical cutting line, an imaging unit that images the optical cutting line irradiated on the object to be measured, and an imaging by the imaging unit. A calibration method used in a three-dimensional shape measuring apparatus including a detection unit that detects a three-dimensional shape of an object to be measured based on a light cutting method from an image including a light cutting line. A three-dimensional calibrator having a plurality of characteristic parts that can be identified by the imaging means when the coordinate value is known and the reflection state with respect to the light cutting line is different is prepared. By irradiating a light cutting line from the irradiation unit, the calibrator irradiated with the light cutting line is picked up by an imaging means, and the light cutting method is applied to the light cutting line reflected in the picked-up image. An image captured by measuring the three-dimensional shape A of the measurement object By using projective transformation for the light cutting line reflected in the object, the three-dimensional shape B of the object to be measured is measured, and the three-dimensional shape A and the three-dimensional shape B are provided in the detection unit so as to coincide with each other. The measured measurement parameter is calibrated.

Preferably, the characteristic part of the calibrator is composed of a surface state, a shape, a pattern, a color, or a combination thereof having different reflection states with respect to the optical cutting line, and the optical cutting line irradiated on the characteristic part is imaged by an imaging unit. In this case, it is preferable that the light cutting line has a ruptured shape or a different luminance in the longitudinal direction.
Preferably, the characteristic part of the calibrator is configured to be surrounded by a curve or a straight line expressed by a monovalent function on the surface of the calibrator.

Preferably, the calibrator is configured by a solid including at least two rectangular panels having a sawtooth pattern on the surface thereof.
Preferably, the detection unit includes a parameter for changing the rotation angle of the imaging unit, a parameter for changing the focal length of the imaging unit, a parameter for changing the baseline length between the irradiation unit and the imaging unit, and the irradiation unit and the imaging unit. Calibration may be performed by setting at least one of the parameters for changing the angle as a measurement parameter and changing the measurement parameter so that the three-dimensional shape A and the three-dimensional shape B coincide.

  Further, a calibrator according to an aspect of the present invention includes an irradiation unit that irradiates a measurement object with an optical cutting line, an imaging unit that images the optical cutting line irradiated on the measurement object, and an imaging by the imaging unit. A calibrator for use in calibrating a three-dimensional shape measuring apparatus including a detection unit that detects a three-dimensional shape of an object to be measured based on a light cutting method from an image including a light cutting line, The calibrator has a three-dimensional shape having a plurality of characteristic parts on the surface, the coordinate values of which are known in real space, and which can be identified by the imaging means due to different reflection states with respect to the light cutting line. It is characterized by that.

Preferably, the characteristic part is configured by a surface state, a shape, a pattern, a color, or a combination thereof having different reflection states with respect to the light cutting line, and when the light cutting line irradiated on the characteristic part is imaged by an imaging unit. It is preferable that the light cutting line has a ruptured shape or a different luminance in the longitudinal direction.
Preferably, the characteristic portion is configured to be surrounded by a curve or a straight line expressed by a monovalent function on the surface of the calibrator.

Preferably, it is good to be comprised by the solid which contains the at least 2 rectangular panel provided with the sawtooth-shaped pattern on the surface.
In addition, a computer program according to an aspect of the present invention includes an irradiation unit that irradiates an object to be measured with an optical cutting line, an imaging unit that images the optical cutting line irradiated on the object to be measured, and an image captured by the imaging unit. A computer program for operating the detection unit of a three-dimensional shape measuring apparatus including a detection unit that detects a three-dimensional shape of an object to be measured based on a light cutting method from an image including a light cutting line, Light from the irradiation unit is applied to a three-dimensional calibrator that has a plurality of characteristic parts on the surface that have known coordinate values in real space and that can be identified by the imaging means due to different reflection states with respect to the light cutting line. The step of irradiating a cutting line and imaging the calibrator irradiated with the optical cutting line with an imaging means, and using the optical cutting method on the optical cutting line reflected in the captured image, 3D shape A step of measuring A, a step of measuring the three-dimensional shape B of the object to be measured by using projective transformation on the light cutting line reflected in the captured image, and the three-dimensional shape A and the three-dimensional And a step of calibrating measurement parameters provided in the detection unit so as to match the shape B.

  A three-dimensional shape measuring apparatus according to an aspect of the present invention includes an irradiation unit that irradiates a measurement object with an optical cutting line, an imaging unit that images the optical cutting line irradiated on the measurement object, and the imaging A detection unit that detects a three-dimensional shape of an object to be measured based on a light cutting method from an image including a light cutting line imaged by the means, a coordinate value in a real space is known, and the light cutting line A calibrator irradiated with a light cutting line from an irradiation unit to a three-dimensional calibrator having a plurality of characteristic parts on the surface that can be identified by the imaging means due to different reflection states, The optical cutting line reflected in the captured image is obtained by measuring the three-dimensional shape A of the object to be measured by using the optical cutting method on the optical cutting line captured by the imaging means and reflected in the captured image. By using projective transformation on the three-dimensional The Jo B were measured, the so three-dimensional shape A and the three-dimensional shape B matches, and having a, a calibration unit for calibrating the measurement parameters provided in the detection portion.

  By using a calibration method, a calibrator and a program, and a three-dimensional shape measuring device used in the three-dimensional shape measuring device according to the present invention, the calibrator can be easily installed in the three-dimensional shape measuring device using the optical cutting method. Can be calibrated easily and accurately.

It is FIG. (1) for demonstrating the calibration method which concerns on embodiment of this invention. It is FIG. (2) for demonstrating the calibration method which concerns on embodiment of this invention. It is FIG. (3) for demonstrating the calibration method which concerns on embodiment of this invention. It is a figure which shows the calibrator which concerns on embodiment of this invention. It is a figure for demonstrating step 1 of the calibration method which concerns on embodiment of this invention. It is a figure for demonstrating step 2 of the calibration method which concerns on embodiment of this invention. It is a figure for demonstrating step 3 of the calibration method which concerns on embodiment of this invention. It is a figure for demonstrating step 4 of the calibration method which concerns on embodiment of this invention. It is a figure for demonstrating step 5 of the calibration method which concerns on embodiment of this invention. It is a figure for demonstrating step 6 of the calibration method which concerns on embodiment of this invention. It is a figure which shows the other panel example of the calibrator which concerns on embodiment of this invention. (A) shows the flowchart of the calibration method which concerns on embodiment of this invention, (b) shows the flowchart of the conventional calibration method.

Hereinafter, a calibration method, a calibrator, a program, and a three-dimensional shape measuring apparatus used in a three-dimensional shape measuring apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.
[Three-dimensional shape measuring device]
In describing the calibration method of the three-dimensional shape measuring apparatus according to the embodiment of the present invention, an outline of a conventional calibration method will also be described. An outline of a conventional calibration method is shown in FIGS. 3 and 12A show an outline of the calibration method according to the embodiment of the present invention.

  As shown in FIGS. 1 to 3, the three-dimensional shape measuring apparatus irradiates an object to be measured with an irradiation unit (line laser 102) that irradiates a cast forged steel product that is an example of the object to be measured with an optical cutting line L. A light cutting sensor 100 comprising an image pickup means (camera 104 for picking up an area image) for picking up the light cutting line L, and an image to be measured based on the light cutting method from the image including the light cutting line L picked up by the image pickup means. A detection unit (personal computer 200) for detecting the three-dimensional shape of the object.

  When measuring the three-dimensional shape of the object to be measured using this three-dimensional shape measuring apparatus, first, the light cutting line L is irradiated from the line laser 102 to the object to be measured, and the light cutting line L is irradiated. The measured object is imaged by the camera 104, and the personal computer 200 calculates the three-dimensional shape of the measured object by using the light cutting method with respect to the light cutting line L reflected in the captured image. By using this three-dimensional shape measuring apparatus, the three-dimensional shape (x, y, z coordinate values) of the object to be measured can be measured from a remote location without contact.

In the three-dimensional shape measuring apparatus, if the positional relationship (distance, angle) between the line laser 102 and the camera 104 deviates from the initial setting value for some reason, that is, if the apparatus alignment is incorrect, the measurement accuracy and reliability The property is insufficient. In order to solve such a problem, the three-dimensional shape measuring apparatus is calibrated.
1 and 12B show a conventional calibration method. In the conventional calibration method, first, the calibrator (target) 300 whose coordinate value in the real space is known is accurately installed at a predetermined position and posture.

  Thereafter, the light cutting line L is irradiated from the line laser 102 so as to accurately coincide with the reference line previously written on the surface of the calibrator 300 and the edge of the calibrator 300. Then, the calibrator 300 is imaged by the camera 104 and an image including the light cutting line L is acquired. The optical cutting line L reflected in the captured image is applied with the optical cutting method in the personal computer 200, and the reference line written on the surface of the calibrator 300 and the three-dimensional shape A of the edge of the calibrator 300 are calculated. Is done. The calculated result is indicated by a dotted line on the personal computer screen of FIG.

On the other hand, with respect to the calibrator 300 that is accurately installed at a predetermined position and posture, the reference line or edge end three-dimensional shape A ′ previously recorded on the surface (the reference line or edge portion in the real space coordinates). The coordinate value is known in advance. The result is shown as a solid line as a three-dimensional shape A ′ on the screen of the personal computer 200 of FIG.
If the device alignment of the three-dimensional shape measuring apparatus is not out of order, the line of the three-dimensional shape A indicated by the dotted line matches the line of the three-dimensional shape A ′ indicated by the solid line, but the device of the three-dimensional shape measuring apparatus When the alignment goes wrong (when calibration is necessary), the dotted line and the solid line shown on the screen of the personal computer 200 are inconsistent.

Therefore, the three-dimensional shape measuring apparatus is calibrated by changing the measurement parameters in the program provided in the personal computer 200 (detection unit) so that the dotted line on the screen of the personal computer 200 overlaps the solid line. Details of the measurement parameters in the program will be described later.
Note that the calibrator 300 in the above-described conventional method has a simple three-dimensional shape, and does not have a characteristic portion on the surface that has a different reflection state (reflectance, surface state, etc.) with respect to the light cutting line L. The surface of the calibrator 300 in the conventional method has substantially uniform properties.

Next, as shown in FIG. 2, consider the case where the position and / or orientation of the calibrator 300 is set incorrectly in such a conventional calibration method.
In this case, since the calibrator 300 is not installed at the correct position and / or orientation, the reference line or edge three-dimensional shape A ′ (in real space coordinates) written in advance on the surface of the calibrator 300 is used. The coordinate values of the reference line and the edge) are unknown. Therefore, calibration such as changing the measurement parameter in the program provided in the personal computer 200 (detection unit) so that the dotted line on the screen of the personal computer 200 overlaps the solid line is meaningless.

That is, the conventional calibration method cannot be applied in a situation where the premise that the calibrator 300 is installed at the correct position and / or posture cannot be strictly observed.
Therefore, as shown in FIGS. 3 and 12A, in the calibration method for the three-dimensional shape measuring apparatus according to the present embodiment, the three-dimensional shape measuring apparatus is calibrated using a calibrator 400 different from the calibrator 300. To do.

  The calibrator 400 has a three-dimensional shape having a plurality of characteristic parts on the surface whose coordinate values in the real space are known and whose reflection states (reflectance, surface state, etc.) with respect to the light cutting line L are different. The calibrator 400 is irradiated with the optical cutting line L from the line laser 102, the calibrator 400 irradiated with the optical cutting line L is imaged by the camera 104, and the optical cutting line L reflected in the captured image is captured. On the other hand, the three-dimensional shape A of the calibrator 400 is measured by using the light cutting method.

On the other hand, the three-dimensional shape B of the calibrator 400 is measured by using projective transformation on the light cutting line L reflected in the captured image. Then, the measurement parameters provided in the personal computer 200 are calibrated so that the three-dimensional shape A and the three-dimensional shape B match.
As described above, the calibrator 400 is provided with a characteristic portion having a different reflection state (reflectance, surface state, etc.) of the light cutting line L on the surface, and the true shape of the calibrator 400 is calculated by projective transformation. The three-dimensional shape measuring apparatus is calibrated by changing the measurement parameters so that the true shape matches the measurement result (dotted line) by the light cutting method.

  As described above, in the calibration method according to the present embodiment, the reflected light of the light cutting line L irradiated to the calibrator 400 having a characteristic pattern that enables projective transformation is imaged, and the imaging data Is subjected to projective transformation to determine the true shape of the calibrator 400, and the measurement parameters are changed so that the true shape matches the measurement result obtained by the light cutting method. Therefore, even if the position and / or orientation of the calibrator 400 is not correct, the three-dimensional shape measuring apparatus can be calibrated accurately and easily.

Hereinafter, details of the calibrator 400 and a detailed calibration method will be described.
[Calibrator]
The calibrator 400 will be described with reference to FIG. As shown in FIG. 4, the calibrator 400 has a stepped three-dimensional shape. At least two rectangular panels irradiated with the light cutting line L are provided with characteristic portions (patterns, marks). This mark is composed of two types.

That is, the calibrator 400 is constituted by a solid (step-shaped solid) including at least two rectangular panels each having a characteristic part (sawtooth pattern). As shown in FIG. 4, the calibrator 400 of this embodiment is a staircase body having three steps, and each step is composed of two rectangular panels orthogonal to each other. A characteristic part is provided on the surface of the rectangular panel.
Considering a two-dimensional coordinate system of a rectangular panel in which the horizontal direction of the rectangular panel is the u ′ coordinate and the vertical direction of the rectangular panel is the v ′ coordinate, the characteristic part is the two-dimensional coordinate system (u′v ′ coordinate system). It has a straight line (mark 1) parallel to one of the coordinate axes and a line (mark 2) composed of a monovalent function that can uniquely identify the other coordinate value for one coordinate value in the two-dimensional coordinate system. doing. The mark 2 may be a straight line or a curved line. Mark 1 and mark 2 are connected.

  The characteristic part of the calibrator 400 of the present embodiment is not limited to the mark 1 and the mark 2 described above, but is a region (sawtooth-shaped pattern region) surrounded by the marks 1 and 2. This region has no or low reflectivity with respect to the light cutting line L. For example, when the light cutting line L emitted from the line laser 102 is infrared, a paint that absorbs infrared is applied to form the characteristic part. Note that this region has a different reflection state with respect to the light cutting line L (including a case where the reflectance is different, including a case where the reflection state is different due to surface unevenness even if the reflectance is the same). Anything that can be identified is acceptable.

Hereinafter, the calibrator 400 will be described in more detail.
In FIG. 4, the mark 1 provided on the surface of the rectangular panel is, for example, a straight line parallel to the upper and lower ends (u ′ coordinates) of the rectangular panel, and at least one is in a positional relationship with the upper and lower ends of the rectangular panel. Known. Here, the upper and lower ends of the rectangular panel are also marked 1. Next, the mark 2 is a line that connects the diagonals of the partitioned areas partitioned by the mark 1, and one line is provided for each partitioned area. Note that the mark 2 may be a curved line. When the mark 2 is a curved line, the u ′ coordinate value and the v ′ are always determined when the position in the rectangular panel is considered in the u′v ′ coordinate system with the upper left vertex of the rectangular panel as the origin. It is necessary that the coordinate value is a monovalent function having a 1: 1 correspondence.

In the calibrator 400 having at least two rectangular panels on which such marks 1 and 2 are formed, the position of the rectangular panel in the calibrator 400 is known. For this reason, projective transformation from the u′v ′ coordinate system of the rectangular panel to the three-dimensional coordinate system in the real space is performed using the configuration method shown below, and the true shape of the calibrator 400 (the light cutting line L hits it). The shape of the part) can be obtained. Therefore, even if the calibrator 400 is not installed at a predetermined position and posture for calibration, the true shape of the calibrator 400 can be obtained.

  Note that the characteristic part of the calibrator 400 is not limited to the mark 1 and the mark 2 described above, and the reflection state with respect to the light cutting line L may be different. For example, the surface state of the calibrator 400 may be configured so that the reflection state with respect to the light cutting line L is different, and may be configured by a shape (unevenness, dent), pattern, color, or a combination thereof. That is, when a light cutting line is irradiated to this feature part, the reflection state of the feature part is different, so that a boundary line can be imaged by the camera 104, and a plurality of feature parts can be identified. In this case, when the light cutting line L irradiated to the characteristic part is imaged by the imaging means, the characteristic part of the calibrator 400 is formed so that the light cutting line L has a different shape in the broken shape or in the longitudinal direction. It only has to be done.

[Calibration method]
With reference to FIGS. 5 to 10, a three-dimensional shape measuring apparatus having the above-described configuration and a method for calibrating the three-way shape measuring apparatus using the calibrator 400 will be described.
This calibration method is generally calibrated by the following six steps. These steps are realized by a program executed on the personal computer 200 constituting the three-dimensional shape measuring apparatus. This program configures a detection unit that detects the three-dimensional shape of the object to be measured from an image including the light cutting line L captured by the camera 104 based on the light cutting method. A calibration unit that calibrates measurement parameters existing in the program is configured by software.

Each step of the calibration method of the present embodiment is as follows.
Step 1 and Step 2: In an image including the light section line L, a plurality of feature points (m _i1 , m _i2 , m _i3 ,...) Including feature points (c0, c1, c2,...) Of the rectangular panel The image coordinate value of is obtained. This process is performed for each panel.
Step 3: The distance between the feature points (m _i1 , m _i2 , m _i3 ,...) In the image coordinates is calculated, and the feature points (M _i1 , M _i2 in the real space coordinates are calculated from the distance ratio in the image coordinates. , M _i3 ,...) _Is calculated.

Step 4: Based on the distance ratio in the real space coordinates, the coordinate values of the feature points (M _i2 , M _i4 ) in the real space coordinates are calculated.
Step 5: Based on the coordinate value of the feature point on one panel in the real space coordinates, the end point of the one panel in the real space coordinates (panel vertex coordinates Ci = M _i1 etc. of the laser apex) is calculated.

Step 6: The end point in the real space coordinates in at least two rectangular panels (the panel-like coordinates Ci = M _i1 etc. of the vertex of the laser) is calculated, and the three-dimensional shape B of the calibrator 400 is calculated. Then, the three-dimensional shape measuring apparatus is calibrated by changing the measurement parameters so that the measurement result (three-dimensional shape A) by the light cutting method matches the three-dimensional shape B of the calibrator 400 in real space coordinates.

The above steps utilize the projective image transformation technique.
Hereinafter, these steps will be described in more detail.
As shown in FIG. 5, in step 1, the laser beam (light cutting line L) is irradiated from the line laser 102 to the calibrator 400 to be measured, and the calibrator 400 is irradiated by the camera 104. And the vertex of the rectangular panel forming the calibrator 400 is detected. Here, the vertices in the real space of the rectangular panel of the calibrator 400 are C0, C1,..., C4, and the vertices on the image captured by the camera 104 are c0, c1,. In real space, C0 and C1 on panel 1 are detected as C1 and C2 on panel 2, C2 and C3 on panel 3, and C3 and C4 on panel 4 are detected as vertices on the image.

As shown in FIG. 6, in step 2, in the image captured by the camera 104, the intersection of the laser beam and all the marks 1 and 2 in each panel is detected as a feature point. “Feature points on the image” detected in panel i are m ₁ , m ₂ , m ₃ , m ₄ , m ₅ ,..., And feature points in real space are M _i1 , M _i2 , M _i3 , M _i4, M _i5, and .... The laser vertices C0, C1, C2,... On the panel are also counted as feature points. That is, if the total number of feature points on the panel 1 is 5, C0 = M ₁₁ , C1 = M ₁₅ = M ₂₁ on the real space, c0 = m ₁₁ , c1 = m ₁₅ = m ₂₁ on the image,. It becomes. Here, it should be noted that on the image captured by the camera 104, the distance between the feature points on the image varies depending on the position of the image capturing means (camera 104).

As shown in FIG. 7, in step 3, from the ratio of the distances between the “feature points on the image” (m _i1 , m _i2 , m _i3 , m _i4 , m _i5 ,...) Detected by the panel i. , The ratio of the distance between “feature points in real space” (M _i1 , M _i2 , M _i3 , M _i4 , M _i5 ,...) Of panel i is obtained. In order to obtain the positional relationship between the feature points in the real space from the positional relationship between the feature points on the image, by using the fact that the cross ratio is constant before and after the projective transformation, the formula shown in FIG. A ratio of distances between feature points is obtained. Thereby, the positional relationship of the feature points in the real space of panel i can be calculated.

As shown in FIG. 8, in step 4, from the ratio of the distance between the “feature points in real space” of panel i obtained in step 3, M _i2 , M _i4 (mark 2 (monovalent on the panel i) The coordinate value of the feature point) on the function) is derived. Incidentally, in FIG. 7, panel-like coordinates _{M ij (u ', v'} ) and are described as _{(M ij (u '),} M ij (v')). Here, since the laser beam is a straight line, the straight line connecting M _i2 and M _i4 becomes the locus of the laser on the panel i as it is. The coordinates on the panel of M _i1 , M _i2 , M _i3 , M _i4 , M _{i5 ,.} From this, the coordinates C _i (= M _i1 ) and C _{i + 1} (= M _i5 ) on the panel of the laser apex are obtained.

As shown in FIG. 9, in step 5, the coordinates of the feature points of each panel are projected onto the coordinates on the target to obtain the coordinates of the vertexes of the laser line. As a result, the three-dimensional shape B (= “true shape”) of the laser beam on the calibrator 400 as the target can be acquired.
As shown in FIG. 10, in step 6, the measurement parameters are adjusted so that the three-dimensional shape B of the calibrator 400 acquired in step 5 and the three-dimensional shape A, which is the measurement result by the optical cutting method, coincide ( Change if necessary). Specifically, the measurement parameters in the program provided in the personal computer 200 are changed so that the three-dimensional shape A displayed on the screen of the personal computer 200 overlaps the three-dimensional shape B.

  In this calibration, a parameter for changing the rotation angle α of the camera 104, a parameter for changing the focal length F of the camera 104, a parameter for changing the baseline length L between the line laser 102 and the camera 104, and the line laser 102 and the camera 104 It is preferable to set at least one of the parameters for changing the angle θ formed as the measurement parameters, and to manipulate these measurement parameters artificially or change them at a constant pitch.

[Effect in the embodiment]
As described above, according to the calibration method, the calibrator and the program, and the three-dimensional shape measuring apparatus used in the three-dimensional shape measuring apparatus according to the present embodiment, the following effects are exhibited.
(A) The calibrator 400 may be placed within the irradiation range of the line laser 102, and it is not necessary to place the calibrator 400 so that its position and posture are exactly a predetermined position and posture. For this reason, when the object to be measured is a large object to be measured, the calibrator is also enlarged, and it is extremely difficult to place the calibrator so that the position and orientation are in a predetermined state. Even when measuring the shape of steel, a calibrator can be easily placed and calibrated accurately.

  (B) Using the optical cutting line L irradiated to the calibrator 400, the three-dimensional shape A of the calibrator 400 is calculated by the optical cutting method, and the true three-dimensional shape B of the calibrator 400 is calculated by projective transformation. can do. That is, the three-dimensional shape A and the three-dimensional shape B can be calculated only by taking the light cutting line L once. By calibrating such that the three-dimensional shape A and the three-dimensional shape B coincide with each other, the three-dimensional shape measuring apparatus can be calibrated accurately and easily.

(C) With the three-dimensional shape measuring apparatus calibrated in this way, an accurate three-dimensional shape that does not include an error can be measured.
[Other marks on the calibrator]
Another mark in the calibrator is shown in FIG. The mark 1 and the mark 2 do not necessarily need to be connected (contacted), and may have the shape of FIG. 11 in which only the central portion of the mark of FIG. 4 is cut out. In addition, the shape of the mark is not limited, and the mark of the calibrator 400 is a curve or straight line (including a line segment as shown in FIG. 11) expressed by a monovalent function on the surface of the calibrator 400. If it is.

  By the way, this invention is not limited to embodiment mentioned above, The shape, structure, material, combination, etc. of each member can be suitably changed in the range which does not change the essence of invention. Further, in the embodiment disclosed this time, matters that are not explicitly disclosed, for example, operating conditions, operating conditions, various parameters, dimensions, weights, volumes, and the like of a component deviate from a range that a person skilled in the art normally performs. However, matters that can be easily assumed by those skilled in the art are employed.

100 Optical cutting sensor 102 Line laser 104 Camera 200 Personal computer (PC)
300 Calibrator (conventional)
400 Calibrator (present invention)

Claims (11)

An irradiating unit for irradiating the object to be measured with an optical cutting line, an imaging unit for imaging the optical cutting line irradiated to the object to be measured, and an optical cutting method from an image including the optical cutting line imaged by the imaging unit. A calibration method used in a three-dimensional shape measuring apparatus including a detection unit that detects a three-dimensional shape of an object to be measured,
Prepared a three-dimensional calibrator having a plurality of characteristic parts on the surface, the coordinate values of which are known in real space and the state of reflection with respect to the light cutting line can be identified by the imaging means,
Irradiate a light cutting line from the irradiation unit to the calibrator,
The calibrator irradiated with the light cutting line is imaged by an imaging means,
Measure the three-dimensional shape A of the object to be measured by using the light cutting method for the light cutting line reflected in the captured image,
Measure the three-dimensional shape B of the object to be measured by using projective transformation for the light cutting line reflected in the captured image,
A calibration method for a three-dimensional shape measuring apparatus, wherein the measurement parameters provided in the detection unit are calibrated so that the three-dimensional shape A and the three-dimensional shape B coincide. The characteristic part of the calibrator is composed of a surface state, a shape, a pattern, a color, or a combination thereof, in which the reflection state with respect to the light cutting line is different.
3. The three-dimensional image according to claim 1, wherein when the light cutting line irradiated to the characteristic part is imaged by an imaging unit, the light cutting line has a ruptured shape or a different luminance in the longitudinal direction. Calibration method for shape measuring device.   3. The three-dimensional shape according to claim 1, wherein the characteristic part of the calibrator is surrounded by a curve or a straight line expressed by a monovalent function on the surface of the calibrator. Calibration method for measuring equipment.   4. The method for calibrating a three-dimensional shape measuring apparatus according to claim 3, wherein the calibrator is configured in a three-dimensional shape including at least two rectangular panels having a sawtooth pattern on the surface thereof. In the detection unit, a parameter for changing the rotation angle of the imaging unit, a parameter for changing the focal length of the imaging unit, a parameter for changing the baseline length between the irradiation unit and the imaging unit, and an angle formed by the irradiation unit and the imaging unit are changed. Set at least one of the parameters to be measured as measurement parameters,
The three-dimensional shape according to any one of claims 1 to 4, wherein calibration is performed by changing the measurement parameter so that the three-dimensional shape A and the three-dimensional shape B coincide with each other. Calibration method for measuring equipment. An irradiating unit for irradiating the object to be measured with an optical cutting line, an imaging unit for imaging the optical cutting line irradiated to the object to be measured, and an optical cutting method from an image including the optical cutting line imaged by the imaging unit. A calibrator used when calibrating a three-dimensional shape measuring apparatus including a detection unit that detects a three-dimensional shape of an object to be measured,
The calibrator has a three-dimensional shape having a plurality of characteristic parts on the surface, the coordinate values of which are known in real space, and which can be identified by the imaging means due to different reflection states with respect to the light cutting line. A calibrator characterized by that. The characteristic part is composed of a surface state, a shape, a pattern, a color, or a combination thereof, which are different in reflection state with respect to the light cutting line,
7. The calibrator according to claim 6, wherein when the optical section line irradiated to the characteristic part is imaged by an imaging unit, the optical section line has a ruptured shape or a different luminance in the longitudinal direction. .   The calibrator according to claim 6 or 7, wherein the characteristic part is configured to be surrounded by a curve or a straight line expressed by a monovalent function on the surface of the calibrator.   The calibrator according to claim 8, wherein the calibrator is constituted by a three-dimensional structure including at least two rectangular panels having a sawtooth pattern on the surface. An irradiating unit for irradiating the object to be measured with an optical cutting line, an imaging unit for imaging the optical cutting line irradiated to the object to be measured, and an optical cutting method from an image including the optical cutting line imaged by the imaging unit. A computer program for operating the detection unit of a three-dimensional shape measuring apparatus including a detection unit that detects a three-dimensional shape of an object to be measured,
Light from the irradiation unit is applied to a three-dimensional calibrator that has a plurality of characteristic parts on the surface that have known coordinate values in real space and that can be identified by the imaging means due to different reflection states with respect to the light cutting line. Irradiating a cutting line and imaging the calibrator irradiated with the optical cutting line with an imaging means;
Measuring the three-dimensional shape A of the object to be measured by using a light cutting method on a light cutting line reflected in the captured image;
Measuring the three-dimensional shape B of the object to be measured by using projective transformation with respect to the light cutting line reflected in the captured image;
And a step of calibrating a measurement parameter provided in the detection unit so that the three-dimensional shape A and the three-dimensional shape B coincide with each other. An irradiation unit for irradiating the object to be measured with an optical cutting line;
Imaging means for imaging a light cutting line irradiated on the object to be measured;
A detection unit that detects a three-dimensional shape of an object to be measured based on a light cutting method from an image including a light cutting line imaged by the imaging unit;
Light from the irradiation unit is applied to a three-dimensional calibrator that has a plurality of characteristic parts on the surface that have known coordinate values in real space and that can be identified by the imaging means due to different reflection states with respect to the light cutting line. 3D of the object to be measured by irradiating the cutting line, imaging the calibrator irradiated with the optical cutting line with an imaging means, and using the optical cutting method for the optical cutting line reflected in the captured image The shape A is measured, and the three-dimensional shape B of the object to be measured is measured by using projective transformation with respect to the light cutting line reflected in the captured image, and the three-dimensional shape A, the three-dimensional shape B, A calibration unit that calibrates the measurement parameters provided in the detection unit so that the
A three-dimensional shape measuring apparatus comprising: