An adaptive optical axis and visual axis consistency correction method

Abstract

A kind of self-adapting optical axis visual axis consistency correction method, comprising: first, the angle between camera coordinate system and laser coordinate system is calibrated, image visual axis is adjusted parallel with guide rail axis using standard long straight line guide rail, the plane target of vertical guide rail is controlled to move on straight line guide rail, image is shot at the nearest working distance and the farthest working distance position, the distance value at two positions is recorded, the pixel coordinates of laser point in image are obtained by image processing, and the spatial coordinates of two light points under camera coordinate system are calculated according to the camera imaging model by the focal length, pixel size parameter of camera, the straight line equation of laser axis is established under camera coordinate system;Then, according to the distance obtained by laser ranging, the actual focal length of camera, pixel size, the pixel coordinates of laser light point deviating from image center at current position are solved using laser axis straight line equation, the original image is sheared and displayed by taking laser point pixel coordinates as center, and the real-time correction of visual axis is realized.

Description

Technical Field

[0001] This invention relates to an adaptive optical axis line-of-sight consistency correction method. This method can ensure that the light spot emitted by the optical axis is always centered in the camera image, regardless of changes in measurement distance and camera focal length. It belongs to the field of photoelectric detection technology. Background Technology

[0002] Three-dimensional coordinate photoelectric detection equipment typically has two mechanical rotating axes and two optical detection axes: a laser ranging optical axis and a camera imaging line of sight. The equipment controls the laser's direction via the mechanical rotating axes, using the measured mechanical angles and laser distance to scan and measure the target's three-dimensional shape. While detecting the target's distance, the operator needs to observe the specific detection position through the camera. However, due to setup errors, there is a small angular deviation between the laser optical axis and the camera imaging line of sight. This deviation increases with distance, resulting in a misalignment between the camera image center and the laser point. Furthermore, the laser point's position relative to the image center changes with target distance, rotation angle, and camera magnification. Therefore, further image processing methods are needed to ensure the laser point remains centered in the image, without significant changes in angle, distance, or camera magnification, thus guaranteeing that the target image displayed at the center is the location of the laser measurement point. Summary of the Invention

[0003] To eliminate the issue of the laser point not being centered in the image due to the inconsistency between the laser ranging optical axis and the camera imaging line of a three-dimensional coordinate photoelectric detection device, an adaptive optical axis and line of sight consistency correction method is proposed. This method can compensate for the amount of laser point deviating from the image center in real time according to changes in target distance, rotation angle, and camera magnification, thereby ensuring that the laser point is always centered in the displayed image.

[0004] The objective of this invention is achieved through the following technical solutions:

[0005] An adaptive optical axis-line consistency correction method first requires calibrating the angle between the camera coordinate system and the laser coordinate system. Using a standard long linear guide rail, the image line of sight is aligned parallel to the guide rail axis. A planar target perpendicular to the guide rail moves along the linear guide rail, and images are captured at both the closest and furthest working distances. The distance values ​​at these two locations are recorded simultaneously. Image processing is used to obtain the pixel coordinates of the laser point in the image. Based on the camera imaging model, the spatial coordinates of the two light points in the camera coordinate system are calculated using the camera's focal length and pixel size parameters. Finally, a straight-line equation for the laser axis is established in the camera coordinate system.

[0006] Then, in the actual measurement process using optoelectronic equipment, based on the distance obtained by laser ranging, the actual focal length of the camera, and the pixel size, the pixel coordinates of the laser point deviating from the image center at the current position can be calculated using the linear equation of the laser axis. By cropping and displaying the original image with the laser point pixel coordinates as the center, real-time correction of the visual axis can be achieved.

[0007] Compared with the prior art, the present invention has the following advantages:

[0008] (1) The method of the present invention can achieve consistency correction of the laser optical axis and the imaging visual axis in the three-dimensional coordinate photoelectric detection device. After correction, the amount of laser spot jumping at the center of the image will be less than 1 pixel.

[0009] (2) The method of the present invention can make the laser spot always visually centered in the image, and its fluctuation is difficult for the human eye to perceive, which helps to improve the operability of the equipment.

[0010] (3) The method of the present invention allows for the existence of consistency error between the optical axis and the visual axis, which helps to reduce equipment installation and adjustment costs and improve production efficiency. Attached Figure Description

[0011] Figure 1 This is a schematic diagram of the structure of a three-dimensional coordinate photoelectric detection device.

[0012] Figure 2 This is a layout diagram for the calibration method.

[0013] Figure 3 To calibrate the target image.

[0014] Reference numerals: 1. Range measuring laser, 2. Monitoring camera, 3. Imaging line of sight, 4. Azimuth axis, 5. Pitch axis, 6. Laser range measuring optical axis, 7. Base; 8. Three-dimensional coordinate photoelectric detection device, 9. Sliding platform, 10. Calibration target, 11. Two-dimensional adjustment platform, 12. Long linear guide rail. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0016] An adaptive optical axis-line consistency correction method includes:

[0017] (1) Place a three-dimensional coordinate photoelectric detection device 8 at one end of the long linear guide rail 12, set the azimuth axis 4 of the three-dimensional coordinate photoelectric detection device 8 to 0° position and the pitch axis 5 to 0° position, and adjust the horizontal bubble of the three-dimensional coordinate photoelectric detection device 8 to the center position.

[0018] (2) Adjust the translation, height and orientation of the three-dimensional coordinate photoelectric detection device 8 by adjusting the base 7 of the three-dimensional coordinate photoelectric detection device 8 so that the light output direction is roughly consistent with the direction of the long straight guide rail 12. The laser emitted by the ranging laser 1 hits the light spot on the correction target 10 on the long straight guide rail 12, and the distance from the center of the correction target 10 is within 2 scales.

[0019] (3) The calibration target 10 consists of a grid scale spaced 10 mm apart, concentric rings, and white circular dots with a black outer ring. The diameter of the dots is 6 mm, and the two dots are located at the center and at the positive Y-axis +60 mm, respectively. The calibration target 10 is fixed on the two-dimensional adjustment stage 11, wherein the X-axis and Y-axis of the calibration target 10 are parallel to the two vertical axes of the two-dimensional adjustment stage 11, respectively.

[0020] (4) The two-dimensional adjustment table 11 is fixed on the sliding platform 9 of the long linear guide rail 12. The two axes of the two-dimensional adjustment table 11 are perpendicular to the axis of the long linear guide rail 12. One axis of the two-dimensional adjustment table 11 is horizontal, and the range of motion of the two axes is greater than 20mm.

[0021] (5) Adjust the azimuth and pitch axes of the three-dimensional coordinate photoelectric detection device 8, and simultaneously adjust the two-dimensional adjustment platform 11 on the calibration target 10, so that during the process of the calibration target 10 moving from one end to the other along the long straight guide rail 12, the image center of the monitoring camera 2 in the three-dimensional coordinate photoelectric detection device 8 always coincides with the center of the dot at the origin on the calibration target 10. The image coordinates of the center dot of the calibration target 10 in the image are extracted subpixel by the feature extraction algorithm. The coordinate change is within 0.5 pixels during the entire journey. Record the current azimuth axis of the three-dimensional coordinate photoelectric detection device 8. and pitch axis ;

[0022] (6) Adjust the position of the calibration target 10 on the long linear guide rail 12 so that it is 1m ± 100mm away from the center of the azimuth axis of the three-dimensional coordinate photoelectric detection device 8. Use the three-dimensional coordinate photoelectric detection device 8 to measure the distance from the three-dimensional coordinate photoelectric detection device 8 to the calibration target 10. ;

[0023] (7) Set the focal length of the monitoring camera 2 in the three-dimensional coordinate photoelectric detection device 8 to the minimum value. An image of the calibration target 10 is captured, and the image coordinates of two dots on the calibration target 10 in the image are extracted subpixel using a feature extraction algorithm. The distance from the image coordinate system to the calibration target 10 is calculated using an ideal imaging model. :

[0024] (1)

[0025] In the formula To monitor the physical size of the camera pixel unit.

[0026] The distance from the image coordinate system to the device coordinate system is calculated using the following formula. :

[0027] (2)

[0028] (8) Turn on the indicator laser of the ranging laser 1, and set the focal length of the monitoring camera 2 of the three-dimensional coordinate photoelectric detection device 8 to the maximum value. ;

[0029] (9) Restore the azimuth axis of the three-dimensional coordinate photoelectric detection equipment 8. and pitch axis Adjust the position of the calibration target 10 on the long linear guide rail 12 so that its distance from the three-dimensional coordinate photoelectric detection device 8 is 1 / 3 of the range of the three-dimensional coordinate photoelectric detection device 8. Use the three-dimensional coordinate photoelectric detection device 8 to measure the distance from the three-dimensional coordinate photoelectric detection device 8 to the calibration target 10. ;

[0030] (10) Finely adjust the azimuth and pitch axes of the three-dimensional coordinate photoelectric detection device 8, and calculate the centroid coordinates of the laser spot in the image acquired by the observation and monitoring camera 2. Stop adjusting when the deviation between the centroid coordinates of the laser spot and the coordinates of the image center is less than 0.2 pixels, and record the current azimuth axis of the three-dimensional coordinate photoelectric detection device 8. and pitch axis ;

[0031] (11) Restore the azimuth axis of the three-dimensional coordinate photoelectric detection equipment 8. and pitch axis Adjust the position of the calibration target 10 on the long linear guide rail 12 so that its distance from the three-dimensional coordinate photoelectric detection device 8 is equal to the maximum range of the three-dimensional coordinate photoelectric detection device 8. Use the three-dimensional coordinate photoelectric detection device 8 to measure the distance from the three-dimensional coordinate photoelectric detection device 8 to the calibration target 10. ;

[0032] (12) Fine-tune according to step 8 so that the deviation between the centroid coordinates of the laser spot and the image center coordinates is less than 0.2 pixels, and record the current azimuth axis of the three-dimensional coordinate photoelectric detection device 8. and pitch axis ;

[0033] (13) Then any distance Different focal lengths and azimuth At that time, the pixel distance between the laser spot emitted by the ranging laser 1 and the center of the image from the monitoring camera 2 is:

[0034] (3)

[0035] (4)

[0036] (14) Shift the overall image center of the monitoring camera 2 according to the above formula. Then, the original image is cropped and displayed with that position as the center, so that the center of the displayed image always coincides with the center of the laser spot emitted by the ranging laser 1, thereby realizing real-time correction between the imaging visual axis 3 and the laser ranging optical axis 6.

[0037] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0038] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by utilizing the methods and techniques disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the protection scope of the technical solutions of the present invention.

Claims

1. An adaptive optical axis-line consistency correction method, characterized in that, include: S1. The angle between the camera coordinate system and the laser coordinate system is calibrated. Using a standard long linear guide rail, the image viewing axis is aligned with the guide rail axis. The planar target on the vertical guide rail is controlled to move on the linear guide rail. Images are captured at the closest and furthest working distance positions, and the distance values ​​at the two positions are recorded. The pixel coordinates of the laser point in the image are obtained through image processing. Based on the camera imaging model, the spatial coordinates of the two light points in the camera coordinate system are calculated using the camera's focal length and pixel size parameters. The linear equation of the laser axis is established in the camera coordinate system. S2. In the actual measurement process of applying optoelectronic equipment, based on the distance obtained by laser ranging, the actual focal length of the camera, and the pixel size, the pixel coordinates of the laser point deviating from the image center at the current position can be calculated using the straight line equation of the laser axis. By cropping and displaying the original image with the laser point pixel coordinates as the center, real-time correction of the line of sight can be achieved. In S1, when calibrating the angle between the camera coordinate system and the laser coordinate system, first place a three-dimensional coordinate photoelectric detection device at one end of the long linear guide rail, set the azimuth axis of the three-dimensional coordinate photoelectric detection device to 0° position, the pitch axis of the three-dimensional coordinate photoelectric detection device to 0° position, and adjust the horizontal bubble of the three-dimensional coordinate photoelectric detection device to the center position. After adjusting the horizontal bubble of the three-dimensional coordinate photoelectric detection device to the center position, adjust the translation, height and orientation of the three-dimensional coordinate photoelectric detection device through the base of the three-dimensional coordinate photoelectric detection device so that the light output direction is consistent with the direction of the long straight guide rail. The laser emitted by the ranging laser hits the light spot on the correction target on the long straight guide rail, and the distance from the center of the correction target is within 2 scales. After the laser emitted by the ranging laser hits the light spot on the calibration target on the long linear guide rail, and the distance to the center of the calibration target is within 2 scales, the two-dimensional adjustment stage is fixed on the sliding platform of the long linear guide rail, and the two axes of the two-dimensional adjustment stage are perpendicular to the axis of the long linear guide rail. With the two-dimensional adjustment platform fixed on a sliding platform of a long linear guide rail, and the two axes of the two-dimensional adjustment platform perpendicular to the axis of the long linear guide rail, the azimuth and pitch axes of the three-dimensional coordinate photoelectric detection equipment are adjusted. Simultaneously, the two-dimensional adjustment platform on the calibration target is adjusted so that, during the movement of the calibration target from one end to the other along the long linear guide rail, the image center of the monitoring camera in the three-dimensional coordinate photoelectric detection equipment always coincides with the center of the origin point on the calibration target. The image coordinates of the center point of the calibration target in the image are extracted sub-pixel using a feature extraction algorithm. The coordinate change is within 0.5 pixels throughout the entire movement. The current azimuth axis of the three-dimensional coordinate photoelectric detection equipment is recorded. and pitch axis ; Record the current azimuth axis of the three-dimensional coordinate photoelectric detection device and pitch axis Then, adjust the position of the calibration target on the long linear guide rail so that it is 1m ± 100mm away from the center of the azimuth axis of the three-dimensional coordinate photoelectric detection equipment. Measure the distance from the three-dimensional coordinate photoelectric detection equipment to the calibration target using the three-dimensional coordinate photoelectric detection equipment. ; Set the focal length of the monitoring camera in the three-dimensional coordinate photoelectric detection device to the minimum value. The image of the calibration target is captured, and the image coordinates of two dots on the calibration target in the image are extracted subpixel using a feature extraction algorithm. The distance from the image coordinate system to the calibration target is calculated using an ideal imaging model. : （1） In the formula To monitor camera pixel size; The distance from the image coordinate system to the device coordinate system is calculated using the following formula. : （2） Turn on the ranging laser pointer and set the focal length of the monitoring camera on the 3D coordinate photoelectric detection device to its maximum value. ; Restore the three-dimensional coordinate photoelectric detection equipment to the azimuth axis and pitch axis Adjust the position of the calibration target on the long linear guide rail so that its distance from the three-dimensional coordinate photoelectric detection device is 1 / 3 of the measurement range of the three-dimensional coordinate photoelectric detection device. Use the three-dimensional coordinate photoelectric detection device to measure the distance from the three-dimensional coordinate photoelectric detection device to the calibration target. ; Fine-tune the azimuth and pitch axes of the 3D coordinate photoelectric detection device, and calculate the centroid coordinates of the laser spot in the image acquired by the observation and monitoring camera. Stop adjusting when the deviation between the laser spot centroid coordinates and the image center coordinates is less than 0.2 pixels, and record the current azimuth axis of the 3D coordinate photoelectric detection device. and pitch axis ; Restore the three-dimensional coordinate photoelectric detection equipment to the azimuth axis and pitch axis Adjust the position of the calibration target on the long linear guide rail so that its distance from the three-dimensional coordinate photoelectric detection device is equal to the maximum range of the three-dimensional coordinate photoelectric detection device. Then, use the three-dimensional coordinate photoelectric detection device to measure the distance from the three-dimensional coordinate photoelectric detection device to the calibration target. ; Measuring the distance from a three-dimensional coordinate photoelectric detection device to a calibration target Afterwards, fine adjustments were made to ensure that the deviation between the coordinates of the laser spot centroid and the coordinates of the image center was less than 0.2 pixels, and the current azimuth axis of the three-dimensional coordinate photoelectric detection device was recorded. and pitch axis ; Then any distance Different focal lengths and azimuth At that time, the pixel distance between the laser spot emitted by the ranging laser and the center of the monitoring camera image is: （3） （4） The overall image center of the surveillance camera is shifted according to the above formula. Then, the original image is cropped and displayed with that position as the center, so that the center of the displayed image always coincides with the center of the laser spot emitted by the ranging laser, thus realizing real-time correction between the imaging line of sight and the laser ranging optical axis. The calibration target consists of a grid with fixed intervals, concentric rings, and white dots with a black outer ring. The two dots are located at the center and a certain point on the positive Y-axis, respectively.

2. The adaptive optical axis and line-of-sight consistency correction method according to claim 1, characterized in that, The X-axis and Y-axis of the calibration target are parallel to the two vertical axes of the two-dimensional adjustment stage, respectively.

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