HK1179684A - System and method for measuring a distance to an object - Google Patents

Description

System and method for measuring distance to an object

Technical Field

The present invention generally involves a system and method for measuring a distance to an object. In particular, various embodiments of the present invention provide signals reflecting the predicted accuracy of distance measurements that may be obtained from one or more images of an object.

Background

Various systems and methods for measuring distances to objects are known in the art. For example, the distance may be calculated using a laser, sound, or other energy pulse reflected off the surface of the object. However, these systems may be prohibitively expensive and/or too large to be accommodated in a confined space. Accordingly, various techniques, commonly referred to as triangulation, stereo measurement, and/or three-dimensional photography, have been developed to calculate one or more distances to an object based on multiple images of the object taken under various changing light conditions. For example, analysis of the length, angle, and/or width of various shadows in an image may be used to calculate the distance to an object. The set of calculated distances to the object may then be used to determine the shape, geometry, or contour of the object.

Existing measurement techniques often allow for the accuracy of various distances to be determined or calculated. However, the accuracy of the various calculated distances is generally based on the captured image and/or based on the calculation of the captured image. Thus, the accuracy of the various calculated distances is generally only available after the time and expense associated with capturing an image of an object has been incurred. In cases where the accuracy of the various distances is less than desired, the time and expense associated with capturing an image of the object must be repeated. Accordingly, a system and method for measuring a distance to an object that provides an indication of the accuracy of subsequent distance calculations would be useful.

Disclosure of Invention

Aspects and advantages of the invention are set forth in, or are apparent from, the following description, or may be learned by practice of the invention.

One embodiment of the present invention is a system for measuring a distance to an object. The system includes a camera positioned at a location and at least one signal generated by the camera at the location, wherein the at least one signal reflects a setting of the camera. A controller is operatively connected to the camera and receives the at least one signal and generates an accuracy signal based on the at least one signal. The accuracy signal reflects a projected accuracy of a distance measurement obtainable from one or more images of an object captured by a camera at the location. An indicator operatively connected to the controller provides an indication reflecting the accuracy signal.

Another embodiment of the invention is a method for measuring a distance to an object. The method includes positioning a camera at a location relative to an object and generating a signal reflecting a projected accuracy of a distance measurement obtainable from one or more images of the object captured by the camera at the location. The method further includes providing an indication reflective of the signal, capturing one or more images of the object at the location, and calculating a distance to the object based on the one or more captured images of the object at the location.

Yet another embodiment of the present invention is a method for measuring a distance to an object that includes positioning a camera at a location relative to the object and determining at least one of an exposure setting or a gain setting of the camera at the location. The method further includes generating a signal based on at least one of an exposure setting or a gain setting of the camera at the location, wherein the signal reflects a projected accuracy of a distance measurement obtainable from one or more images of the object captured by the camera at the location. Additionally, the method includes providing an indication reflecting the signal, capturing one or more images of the object at the location, and calculating a distance to the object based on the one or more captured images of the object at the location.

Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.

Drawings

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth more particularly in the remainder of the specification, which makes reference to the appended figures in which:

FIG. 1 is a functional block diagram of a system for measuring distance to an object according to one embodiment of the present invention;

FIG. 2 is an algorithm for a method of measuring distance to an object according to one embodiment of the present invention;

FIG. 3 is an exemplary visual indication in a viewfinder;

FIG. 4 is an exemplary three-dimensional image of an object generated by the system based on the conditions depicted in FIG. 3;

FIG. 5 is an exemplary visual indication in a viewfinder; and

FIG. 6 is an exemplary three-dimensional image of an object generated by the system based on the conditions depicted in FIG. 5.

Detailed Description

Reference will now be made in detail to the present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter codes to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention.

Each example is provided by way of illustration of the invention and not by way of limitation. Indeed, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment, can be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Various embodiments of the present invention provide systems and methods for measuring a distance to an object, and this distance to the object may then be used to determine the shape, geometry, or contour of the object. Systems and methods provide an indication reflecting the accuracy of distance measurements that may be obtained from one or more images of an object captured by a camera at a particular location. Based on the indication, the camera may be repositioned prior to capturing one or more images to achieve a desired accuracy of the distance measurement, if desired.

FIG. 1 provides a functional block diagram of a system 10 for measuring a distance 12 to an object 14 according to one embodiment of the present invention. The system 10 generally includes a camera 16 operatively connected to a controller 18. As used herein, the term "camera" includes any device capable of capturing one or more images of an object, such as digital or analog cameras known in the art. For example, as shown in FIG. 1, the camera 16 may include an aperture 20, a retractable shutter 22 that alternately covers or uncovers the aperture 20, a lens 24 for collecting light, and a light 26 for illuminating the object 14. To capture an image, the shutter 22 exposes the aperture 20, and the lens 24 focuses light passing through the aperture 20 onto the recording medium 28.

The camera 16 may incorporate a borescope or other device (not shown) known in the art for positioning the camera 16 at a position relative to the object 14. Once positioned at the location, the camera 16 generates a plurality of signals to the controller 18 that convey or reflect various settings in the camera 16, and a combination of one or more of the signals may be used to determine the relative distance to the object. For example, the camera 16 may generate a light signal 30 reflecting a light setting (e.g., on, off, or brightness), an exposure signal 32 reflecting an exposure setting (e.g., aperture 20 width, shutter 22 speed), and/or a gain signal 34 reflecting a gain setting associated with the camera 16. Each setting may be established manually by an operator or automatically through conventional operating procedures or programming included in the camera 16. For example, assuming that the illumination produced by the lamp 26 is not collimated, the reflected intensity of the illumination is proportional to the square of the distance to the object. Thus, for a given light intensity, the exposure setting and/or gain setting must be increased to maintain a given image brightness level as the distance to the object increases. Thus, for a given light signal 30, the exposure signal 32 and the gain signal 34 may be used to predictably indicate the relative distance to the object. Those skilled in the art will appreciate that the camera 16 may have additional settings and generate additional signals in this particular embodiment, and the foregoing examples are not meant to be an exhaustive list of all settings associated with the camera 16 and/or signals generated by the camera 16.

As described herein, a technical effect of the controller 18 is to generate the accuracy signal 36 based on one or more of the signals 30, 32, 34 generated by the camera 16. The controller 18 may comprise a stand-alone component or a sub-component included in any computer system known in the art, such as a laptop, personal computer, mini-computer, or mainframe computer. The various controllers 18 and computer systems discussed herein are not limited to any particular hardware architecture or configuration. Embodiments of the systems and methods set forth herein may be implemented by one or more general purpose or custom controllers adapted in any suitable manner to provide the desired functionality. For example, the controller 18 may be adapted to provide additional functionality that is complementary to or unrelated to the present subject matter. When software is used, any suitable programming, scripting, or other type of language or combination of languages may be used to implement the teachings contained herein. However, some of the systems and methods set forth and disclosed herein may also be implemented by hard-wired logic or other circuitry, including but not limited to application-specific circuitry. Of course, various combinations of computer-executed software or hardwired logic or other circuitry may be suitable.

The controller 18 receives one or more of the signals 30, 32, 34 and compares these signals, individually or collectively, to one or more predetermined limits. For example, the accuracy of most triangulation-based measurement systems decreases non-linearly as the distance to the object increases, and the predetermined limits may include various combinations of light signals 30, exposure signals 32, and/or gain signals 34 that map to the expected accuracy of the distance measurement. The controller 18 may thus determine the projected accuracy of the distance measurements that may be obtained from one or more images of the object 14 captured by the camera 16 at the location based on this comparison of one or more of the signals 30, 32, 34, individually or collectively, with one or more predetermined limits. For example, the high light signal 30, the low exposure signal 32, and the low gain signal 34 may individually or in some common combination indicate very good conditions for capturing an image of the object 14, resulting in higher prediction accuracy. Conversely, the low light signal 30, the high exposure signal 32, and the high gain signal 34 may indicate, individually or in some common combination, less favorable conditions for capturing an image of the object 14, resulting in lower prediction accuracy. Those skilled in the art will readily appreciate that the actual signals compared and the relative weights applied to each signal may be determined without undue experimentation or research based on various specific parameters, such as the particular camera 16, the surface characteristics of the object 14, the expected distance, and predetermined limits.

As shown in fig. 1, the controller 18 generates an accuracy signal 36 based on one or more of the signals 30, 32, 34, where the accuracy signal 36 reflects a projected accuracy of the distance measurement that may be obtained from one or more images of the object 14 captured by the camera 16 at the location. An indicator operatively connected to controller 18 receives accuracy signal 36 and provides an indication reflecting accuracy signal 36. The indication may include, for example, a visual display 38, such as a digital or analog icon, included in a viewfinder 40 that conveys the accuracy signal 36 to the operator. Alternatively, or in addition, the indication may include a speaker that produces an audio indication or sound 42 that similarly conveys the accuracy signal 36 to the operator.

Fig. 2 provides a flowchart or algorithm for a method of measuring distance to the object 14, and fig. 3-6 provide various visual displays 38 and three-dimensional images of the object 14 to illustrate the method, according to one embodiment of the invention. At block 50, the operator positions the camera 16 at a position relative to the object 14. At block 52, various settings are established, either automatically or manually, in the camera 16 to improve video capture of the object 14 at that location. For example, conventional operating procedures or programming included in the camera 16 may be used to automatically establish various settings, such as the brightness of the lights 26, the speed of the door 22, focus, gain, and various other optical settings available in the camera 16. Alternatively, or in addition, the operator may manually establish or override any of the settings, as desired. At block 54, the camera 16 determines the settings and generates one or more signals to the controller 18 reflecting the settings. For example, as previously described, the camera 16 may generate the light signal 30, the exposure signal 32, and/or the gain signal 34 to the controller 18.

At diamond 56, the controller 18 compares one or more signals 30, 32, 34 to one or more predetermined limits and generates a signal 36 reflecting the predicted accuracy of the distance measurement that may be obtained from one or more images of the object 14 captured by the camera 16 at the location. At block 58, the signal 36 generates an indication (e.g., visual or audible) that reflects the signal 36 and thus the expected accuracy. For example, as shown in FIG. 3, the vision 38 in the viewfinder 40 reflects the relatively low expected accuracy of any distance measurements obtained from one or more images of the object 14 captured by the camera 16 at the location. Thus, the operator may begin the method through box 50 by relocating the camera 16 to a new location, as indicated by line 60 in fig. 2. In contrast, the visual display 38 in the viewfinder 40 shown in FIG. 5 reflects the relatively high expected accuracy of any distance measurements obtained from one or more images of the object 14 captured by the camera 16 at the location. Thus, the operator may continue with additional image captures and calculate the distance to the object 14.

At block 62, the system 10 captures one or more images of the object 14, and at block 64, the system 10 uses the captured images to determine or calculate one or more distances to the object 14. For example, system 10 may variously employ one or more techniques known as triangulation, stereo measurement, and/or three-dimensional photography, although the particular measurement technique is not a limitation of the present invention unless specifically recited in the claims. FIG. 4 provides an exemplary three-dimensional image 66 of object 14 generated by system 10 based on the conditions depicted in FIG. 3. As shown in fig. 4, the calculated distance to the object 14 is relatively inaccurate, producing a correspondingly inaccurate three-dimensional image 66 that includes a large amount of noise and other indicia of inaccurate measurements or contours of the surface of the object 14. In contrast, FIG. 6 provides an exemplary three-dimensional image 66 of object 14 generated by system 10 based on the conditions depicted in FIG. 5. As shown in fig. 6, the calculated distance to object 14 is relatively accurate, resulting in a correspondingly accurate three-dimensional image 66 that more closely approximates the contour of object 14. Thus, the various systems and methods of the present invention provide an indication of the projected accuracy of the distance measurement to the operator before the operator proceeds with the time-consuming and potentially expensive image capture and distance calculation process, allowing the operator to reposition or adjust the camera 16 to achieve the desired accuracy.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

Parts list

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Claims (14)

1. A system (10) for measuring a distance (12) to an object (14), comprising:

a. a camera (16) disposed at a location;

b. at least one signal (30, 32, 34) generated by the camera (16) at the location, wherein the at least one signal (30, 32, 34) reflects a setting of the camera (16);

c. a controller (18) operatively connected to the camera (16), wherein the controller (18) receives the at least one signal (30, 32, 34) and generates an accuracy signal (36) based on the at least one signal (30, 32, 34), wherein the accuracy signal (36) reflects a projected accuracy of a distance (12) measurement obtained from one or more images of the object (14) captured by the camera (16) at the location; and

d. an indicator (38, 42) operatively connected to the controller (18), wherein the indicator (38, 42) provides an indication reflecting the accuracy signal (36).

2. The system (10) of claim 1, further comprising a predetermined limit, wherein the controller (18) compares the at least one signal (30, 32, 34) to the predetermined limit.

3. The system (10) according to any one of claims 1-2, wherein the indication includes a visual display (38).

4. The system (10) according to any one of claims 1-3, wherein the indication includes a sound (42).

5. The system (10) as in any one of claims 1-4, wherein the at least one signal (32, 34) reflects at least one of an exposure setting or a gain setting of the camera (16) at the location.

6. The system (10) of any of claims 1-5, further comprising a light (26) operatively connected to the camera (16).

7. A method for measuring a distance (12) to an object (14), comprising:

a. positioning a camera (16) at a position relative to the object (14);

b. generating a signal (36) indicative of a predicted accuracy of distance (12) measurements obtained from one or more images of the object (14) captured by the camera (16) at the location;

c. providing an indication (38, 42) reflecting the signal (36);

d. capturing one or more images of the object (14) at the location; and

e. calculating a distance (12) to the object (14) based on one or more captured images of the object (14) at the location.

8. The method of claim 7, further comprising displaying a visual indication (38) reflecting the signal (36).

9. The method of any of claims 7-8, further comprising generating an audio indication (42) reflective of the signal (36).

10. The method of any of claims 7-9, further comprising determining at least one of an exposure setting or a gain setting of the camera (16) at the location.

11. The method of any of claims 7-10, further comprising comparing at least one of an exposure setting or a gain setting of the camera (16) at the location to a predetermined limit.

12. The method of any of claims 7-11, further comprising generating the signal (36) based on at least one of an exposure setting or a gain setting of the camera (16) at the location.

13. The method of any of claims 7-12, further comprising generating a three-dimensional image (66) of the object (14).

14. The method of any one of claims 7-13, further comprising illuminating the object (14).