阅读说明：本技术 激光测距器光轴偏差自动测量装置及测量方法 (automatic measuring device and method for optical axis deviation of laser range finder ) 是由 赵鹏飞 吴涛 李元 于 2019-08-30 设计创作，主要内容包括：本发明涉及激光测距器光轴偏差自动测量装置及测量方法,包括激光测距器和感光靶板,所述感光靶板上设有多个已标定坐标的参考基准点光源,连接各参考基准点光源形成的多边形中心为理论激光照射点,所述感光靶板配合有近红外工业相机采集基准点光源和激光光斑图像,激光光斑利用参考基准点映射计算激光光斑偏移量；对图像进行梯形校正、增强、去噪,最后确定光斑中心坐标,映射成世界坐标系下的坐标值。本发明通过近红外工业相机采集感光靶板的图像信息,同时采取参考点映射的方式计算光斑偏移量,相比原感光相纸法,有效提高了检测精度和测试效率。(the invention relates to an automatic measuring device and a measuring method for optical axis deviation of a laser range finder, and the automatic measuring device comprises the laser range finder and a photosensitive target plate, wherein a plurality of reference point light sources with calibrated coordinates are arranged on the photosensitive target plate, the center of a polygon formed by connecting the reference point light sources is a theoretical laser irradiation point, the photosensitive target plate is matched with a near-infrared industrial camera to collect reference point light sources and laser spot images, and laser spots are mapped by using reference points to calculate the offset of the laser spots; and performing trapezoidal correction, enhancement and denoising on the image, and finally determining the central coordinate of the light spot and mapping the central coordinate to a coordinate value under a world coordinate system. According to the invention, the image information of the photosensitive target plate is acquired by the near-infrared industrial camera, and the light spot offset is calculated by adopting a reference point mapping mode.)

1. Laser range finder optical axis deviation automatic measuring device, including laser range finder and sensitization target plate, its characterized in that: the laser spot imaging device is characterized in that a plurality of reference point light sources with calibrated coordinates are arranged on the photosensitive target plate, the center of a polygon formed by connecting the reference point light sources is a theoretical laser irradiation point, the photosensitive target plate is matched with a near-infrared industrial camera to collect the reference point light sources and a laser spot image, and the laser spot image is mapped by using the reference points to calculate the laser spot offset.

2. The method for measuring an optical axis deviation automatic measuring device of a laser range finder as claimed in claim 1, characterized in that: the method comprises the following steps:

The first step is as follows: opening a laser range finder to form light spots on the photosensitive target plate, and collecting image information on the photosensitive target plate by a near-infrared industrial camera;

The second step is that: trapezoidal correction is carried out on the image information, and the reference datum point is mapped into a rectangle;

the third step: enhancing and denoising the corrected image;

the fourth step: positioning the central coordinates of the light spots;

the fifth step: and mapping the central coordinates of the light spots into specific coordinate values in a world coordinate system.

3. The method of claim 2 for measuring the optical axis deviation of the laser range finder: the method is characterized in that: locating the spot center coordinates includes the steps of:

The first step is as follows: determining the position (x) of the center of the pixel₀，y₀) Finding a point (x, y) where all pixel values in the graph are 0;

the second step is that: determining the distance (x) from the theoretical laser irradiation point_m，y_m) Nearest point (x)_i，y_i) And a distance r from a theoretical laser irradiation point_m；

The third step: moving the theoretical laser irradiation point to be in contact with the point (x)_i,y_i) The distance of the laser beam is increased by 1 in the straight line direction, and meanwhile, the theoretical laser irradiation point position is updated;

the fourth step: continuously repeating the second step and the third step until the minimum distance r is calculated_minStopping the calculation, this time point (x)_min，y_min) Namely the central point of the light spot.

4. The method of claim 2 for measuring the optical axis deviation of the laser range finder: the method is characterized in that: and the distance of the reference datum point under the world coordinate system is known, and a distance mapping relation between the image coordinate system and the world coordinate system is established.

5. The method of claim 3 for measuring the optical axis deviation of the laser range finder: the method is characterized in that: the distance r_mthe calculation formula of (2) is as follows:

6. the automatic measuring device of the optical axis deviation of the laser range finder as claimed in claim 1: the method is characterized in that: the number of the reference datum point light sources is four, and the center of a rectangle formed by connecting the four reference datum points is a theoretical laser irradiation point.

7. The method of claim 2 for measuring the optical axis deviation of the laser range finder: the method is characterized in that: and thirdly, enhancing and denoising the image by using a histogram equalization method and a median filtering method.

8. The method of claim 2 for measuring the optical axis deviation of the laser range finder: the method is characterized in that: and (4) carrying out binarization processing on the image before the central coordinates of the light spots are positioned.

Technical Field

The invention relates to the field of laser ranging, in particular to an automatic measuring device and a measuring method for optical axis deviation of a laser range finder.

background

The laser axis calibration of the traditional airborne laser range finder is completed by combining a special target plate with photosensitive photographic paper, the photosensitive photographic paper is pasted on the special target plate, a datum point is calibrated, laser is radiated to the photosensitive photographic paper, a light spot is formed after firing, and the offset of the laser axis is calculated by manually measuring the error value of the light spot and the datum point; the invention provides an automatic correction device for optical axis deviation of a laser range finder and a test method thereof, which are used for improving higher calibration precision and efficiency because the special near-distance photographic paper for laser printing has larger laser energy attenuation under the long-distance condition, and burning light spots formed by laser radiation on the near-distance photographic paper are not obvious and cannot be accurately interpreted, thus causing larger error of measurement deviation.

Disclosure of Invention

in order to solve the technical problems, the invention provides a device and a method for measuring and correcting the optical axis deviation of a laser range finder. The technical problem to be solved by the invention is realized by adopting the following technical scheme:

The automatic measuring device for the optical axis deviation of the laser range finder comprises the laser range finder and a photosensitive target plate, wherein a plurality of reference point light sources with calibrated coordinates are arranged on the photosensitive target plate, the center of a polygon formed by connecting the reference point light sources is a theoretical laser irradiation point, the photosensitive target plate is matched with a near-infrared industrial camera to collect the reference point light sources and a laser spot image, and the laser spot image is mapped by using the reference points to calculate the laser spot offset.

The method for measuring the optical axis deviation of the laser range finder comprises the following steps:

The first step is as follows: opening a laser range finder to form light spots on the photosensitive target plate, and collecting image information on the photosensitive target plate by a near-infrared industrial camera;

The second step is that: trapezoidal correction is carried out on the image information, and the reference datum point is mapped into a rectangle;

The third step: enhancing and denoising the corrected image;

The fourth step: positioning the central coordinates of the light spots;

the fifth step: and mapping the central coordinates of the light spots into specific coordinate values in a world coordinate system.

Locating the spot center coordinates includes the steps of:

The first step is as follows: determining the position (x) of the center of the pixel₀，y₀) Finding a point (x, y) where all pixel values in the graph are 0;

the second step is that: determining the distance (x) from the theoretical laser irradiation point_m，y_m) Nearest point (x)_i，y_i) Theory of harmonyDistance r of laser irradiation point_m；

The third step: moving the theoretical laser irradiation point to be in contact with the point (x)_i,y_i) The distance of the laser beam is increased by 1 in the straight line direction, and meanwhile, the theoretical laser irradiation point position is updated;

the fourth step: continuously repeating the second step and the third step until the minimum distance r is calculated_minStopping the calculation, this time point (x)_min，y_min) Namely the central point of the light spot.

And the distance of the reference datum point under the world coordinate system is known, and a distance mapping relation between the image coordinate system and the world coordinate system is established.

the distance r_mthe calculation formula of (2) is as follows:

The number of the reference datum point light sources is four, and the center of a rectangle formed by connecting the four reference datum points is a theoretical laser irradiation point.

And thirdly, enhancing and denoising the image by using a histogram equalization method and a median filtering method.

And (4) carrying out binarization processing on the image before the central coordinates of the light spots are positioned.

The invention has the beneficial effects that: according to the invention, the image information of the photosensitive target plate is acquired by the near-infrared industrial camera, and the light spot offset is calculated by adopting a reference point mapping mode.

The invention enhances the light spot definition and effectively improves the accuracy of the light spot center coordinate by performing trapezoidal correction, enhancement, denoising and binarization processing on the image.

Drawings

the invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a schematic diagram of the system of the present invention;

FIG. 2 is a schematic view of the working process of the present invention;

FIG. 3 is an exemplary graphical process flow of the present invention;

FIG. 4 is a schematic view of a photosensitive target plate according to the present invention;

FIG. 5 is a schematic diagram of trapezoidal correction according to the present invention.

Detailed Description

in order to make those skilled in the art better understand the technical solution of the present invention, the present invention will be described more clearly and more completely with reference to the drawings in the following embodiments, and it is understood that the described embodiments are only a part of the present invention, rather than all of the present invention, and based on the embodiments, other embodiments obtained by those skilled in the art without inventive exercise are within the protection scope of the present invention.

As shown in fig. 1 to 5, the automatic measuring device for the optical axis deviation of the laser range finder comprises a laser range finder and a photosensitive target plate, wherein a plurality of reference point light sources with calibrated coordinates are arranged on the photosensitive target plate, the center of a polygon formed by connecting the reference point light sources is a theoretical laser irradiation point, the photosensitive target plate is matched with a near-infrared industrial camera to collect reference point light sources and laser spot images, and the offset of laser spots is calculated by mapping the laser spot images by using the reference points; as shown in figure 1, the height difference h exists between the industrial camera and the photosensitive target plate, so that excessive distortion of the image is prevented when the laser spot image is collected, and the integrity of the collected image is ensured.

the method for measuring the optical axis deviation of the laser range finder comprises the following steps:

The first step is as follows: opening a laser range finder to form light spots on the photosensitive target plate, and collecting image information on the photosensitive target plate by a near-infrared industrial camera; processing image information obtained by shooting by a near-infrared industrial camera through a computer;

The second step is that: trapezoidal correction is carried out on the image information, and the reference datum point is mapped into a rectangle; imaging distortion exists when the near-infrared industrial camera shoots an object, trapezoidal distortion may exist in the four reference points in actual imaging due to perspective, and therefore trapezoidal correction needs to be carried out on image information to map the four reference points on the photosensitive target plate into a rectangle;

The third step: enhancing and denoising the corrected image;

the fourth step: positioning the central coordinates of the light spots; firstly, converting an image into a gray image, finding a proper threshold value of the image by using a maximum inter-class variance method, then carrying out binarization on the image, and carrying out binarization processing on the image to extract a spot edge contour;

The fifth step: mapping the central coordinates of the light spots into specific coordinate values under a world coordinate system; and the second step to the fifth step are processed by medium and short distance laser high-precision measurement software integrated in a computer.

locating the spot center coordinates includes the steps of:

the first step is as follows: determining the position (x) of the center of the pixel₀，y₀) Finding a point (x, y) where all pixel values in the graph are 0;

the second step is that: determining the distance (x) from the theoretical laser irradiation point_m，y_m) Nearest point (x)_i，y_i) And a distance r from a theoretical laser irradiation point_m；

the third step: moving the theoretical laser irradiation point to be in contact with the point (x)_i,y_i) The distance of the laser beam is increased by 1 in the straight line direction, and meanwhile, the theoretical laser irradiation point position is updated;

The fourth step: continuously repeating the second step and the third step until the minimum distance r is calculated_minstopping the calculation, this time point (x)_min，y_min) Namely the central point of the light spot; minimum distance r_minBy theoretical laser irradiation spot (x)_m，y_m) And coordinates of a point (x, y) having a pixel value of 0 are calculated, the second and third steps are loop calculations, each loop determines whether the calculated distance is less than the distance of the previous loop, and since the number of the points (x, y) having a pixel value of 0 is known, the minimum distance r can be finally determined after the loop calculations_min(ii) a Fig. 3 is an example of a graphic processing flow, where the coordinates of the center of the light spot are x-304.3342 and y-171.6652.

The distance of the light spot center coordinate mapping is known in a world coordinate system by using a reference datum point, and a distance mapping relation corresponding to the image coordinate system and the world coordinate system is established; and mapping the coordinates of the central point of the light spot into specific coordinate values in a world coordinate system according to the mapping relation.

The distance r_mThe calculation formula of (2) is as follows:Since the number of the points (x, y) having the pixel value of 0 is known, the minimum distance r can be finally determined after the loop calculation_min。

The number of the reference datum point light sources is four, and the center of a rectangle formed by connecting the four reference datum points is a theoretical laser irradiation point.

Thirdly, enhancing and denoising the image by using a histogram equalization method and a median filtering method; before the center of the light spot is positioned, the influence of small bright spots, small dark spots and other stray light except the light spot in the image needs to be eliminated, and the image is enhanced by adopting a histogram equalization method; the method is an image enhancement algorithm for changing the gray level probability density distribution of an input image, has relatively good robustness and can achieve a good enhancement effect; because the image noise of the light spot influences the centroid precision, the median filtering method is adopted to carry out denoising processing on the laser light spot; the method changes the pixel with larger difference ratio with the gray value of the surrounding pixel into the value close to the value of the surrounding pixel, thereby eliminating the isolated noise point and keeping the important structural characteristics of the image.

before the central coordinates of the light spots are positioned, carrying out binarization processing on the image; firstly, converting an image into a gray image, finding a proper threshold value of the image by using a maximum inter-class variance method, then carrying out binarization on the image, carrying out binarization processing on the image to extract a light spot edge contour, and solving the position (x) of a pixel center by averaging a white part of the image, namely a part with a pixel value of 1 because the binary image value is only 0 and 1₀,y₀) I.e. thereinSubsequently using (x)₀,y₀) And calculating to obtain the center coordinates of the light spots.

The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are merely illustrative of the principles of the invention, but that various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.