CN109059800A - A kind of light source position calibration method of three-dimensional reconstruction apparatus - Google Patents

A kind of light source position calibration method of three-dimensional reconstruction apparatus Download PDF

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Publication number
CN109059800A
CN109059800A CN201810507975.1A CN201810507975A CN109059800A CN 109059800 A CN109059800 A CN 109059800A CN 201810507975 A CN201810507975 A CN 201810507975A CN 109059800 A CN109059800 A CN 109059800A
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light source
dimensional reconstruction
camera
plane
image
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CN109059800B (en
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宗诗皓
翟理想
赵雅丛
樊兆雯
仲雪飞
张�雄
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Southeast University
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Southeast University
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B21/00Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant
    • G01B21/02Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness
    • G01B21/04Measuring arrangements or details thereof, where the measuring technique is not covered by the other groups of this subclass, unspecified or not relevant for measuring length, width, or thickness by measuring coordinates of points
    • G01B21/042Calibration or calibration artifacts
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01BMEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00Measuring arrangements characterised by the use of optical techniques
    • G01B11/24Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

The present invention provides a kind of light source position calibration method of three-dimensional reconstruction apparatus, including light source group, camera, controller, plane template and image processor, the light source position calibration of its provided three-dimensional reconstruction apparatus includes three links, it is under operation link, built-in three-dimensional reconstruction algorithm can be passed through, light source position parameter in adjustment algorithm, three-dimensional reconstruction is carried out to plane template using one group of photo that plane template is shot as object using in shooting link, the best light source location parameter is determined by reconstructed results, influence of the installation error of light source and camera to reduction precision can be reduced, effectively improve the quality of three-dimensional reconstruction.

Description

A kind of light source position calibration method of three-dimensional reconstruction apparatus
Technical field
The present invention relates to three-dimensional reconstruction the relevant technologies technical field more particularly to a kind of light source positions of three-dimensional reconstruction apparatus Calibration method.
Background technique
Nowadays three-dimensional reconstruction apparatus is widely used in production practices and daily life.Currently, a kind of common Three-dimensional Gravity The mode of building is the gray difference estimation body surface normal vector by object under different illumination conditions, and advantage is thin to texture The recovery capability of section is prominent, but to the calibration request of light source parameters height, in reduction precision by light source and camera installation error Influence, it is therefore desirable to design it is a kind of can influence with light source and camera installation error to reduction precision Source calibration method.
Summary of the invention
Technical problem: to solve the above problems, the present invention provides a kind of light source position of three-dimensional reconstruction apparatus Calibration method, including light source group, camera, controller, plane template and image processor, it is possible to reduce the peace of light source and camera Influence of the error to reduction precision is filled,
Technical solution: the present invention is a kind of light source position calibration method of three-dimensional reconstruction apparatus, the three-dimensional reconstruction apparatus Including light source group, camera, controller, plane template and image processor, wherein camera is located at centre, and light source group includes light Source one, light source two, light source three, light source four are located at 4 sides of camera, and plane template is located at the top of camera and light source group;
The light source position calibration method of the three-dimensional reconstruction apparatus includes shooting link, prepares link and operation link;It claps It takes the photograph under link and is shot by camera, obtain flat image, in preparing link, the flat image of shooting is subjected to gray processing processing, The offset coordinates that operation link obtains when error coefficient is minimized are denoted as most suitable coordinate;It is after operation link if described It detects step-length and is greater than 2 pixels, then the lattice point being overlapped in the detection grid with most suitable coordinate distance is greater than detection The lattice point of step-length is deleted;The detection step-length is halved and adds new lattice point in the detection grid;The inspection The distance of neighboring lattice points of the survey grid lattice after being added to the lattice point is detection step-length, and the detection grid area is not Increase;Subsequent repetitive operation link;If the detection step-length is less than 2 pixels after operation link, by it is described most Suitable coordinate is denoted as optimized migration coordinate.
Wherein:
The shooting link are as follows: each light source inside controller control light source group is successively lighted, and in each light source The plane template that camera shooting is placed in front of the light source group and the camera is controlled after lighting at once, is obtained One group of photo be known as the first flat image.
The preparation link is using plane where first flat image as x-y plane, with the first flat image left side Upper angle is that origin establishes three-dimensional cartesian coordinate system;In the image processor setting detection step-length, along x, y-axis direction is established flat For row in the detection grid of (x, y) plane, neighboring lattice points spacing is the detection step-length, the z of the three-dimensional cartesian coordinate system Axis is by wherein one of a certain lattice point, and the camera position detection grid coplanar and described with the detection grid is to z=0 The projection of plane is entirely located within first plan view image.
Under the operation link, (x, y) coordinate of offset coordinates is successively set as the detection net by image processor (x, y) coordinate of each lattice point in lattice, by the z coordinate of the offset coordinates be set as camera and the plane template away from From;Three-dimensional reconstruction algorithm and first flat image built in the image processor is to the plane mould Plate carries out three-dimensional reconstruction, obtains the first areal model;By the first areal model upright projection to x-y plane, and throwing Shadow zone domain is evenly dividing along x, y-axis as the Error Grid having a size of m*n;In first areal model with the Error Grid lattice point There is the set of the point of identical (x, y) coordinate to be denoted as first cloud;
First cloud is fitted to by image processing unit in the three-dimensional cartesian coordinate system under operation link One plane, referred to as the second plane;It is flat at a distance from second plane to calculate point all in first cloud Fang He, referred to as error coefficient;Compare the offset coordinates and is located at the error obtained when each lattice point in the detection grid Coefficient, recording error coefficient minimum value, the offset coordinates when error coefficient is minimized are denoted as most suitable coordinate.
The light source group includes 4 light sources, is mounted on the midpoint on 4 sides of the square that side length is s;The camera (2) square center and its optical axis direction are mounted on perpendicular to the square;When shooting, each light Source has and only one is in illuminating state;The brightness of each light source is identical and distance to each other can be measured accurately.
The image processing unit passes through light in the grayscale information in first plan view image, the light source group The distance between source, the coordinate of the camera and the distance between itself and the plane template calculate described first Areal model.
First flat image includes 4 pictures, will obtain 4 grayscale images after the 4 picture gray processings, The pixel of same position has corresponded to the same point in areal model in 4 grayscale images;If the grayscale image is having a size of m*n picture Element is horizontally to the right y-axis direction, is vertically downward x-axis direction using the pixel in the grayscale image upper left corner as origin, direction The direction of the camera is that z-axis positive direction establishes rectangular coordinate system;1 millimeter in the plane template of length is located in institute R pixel is corresponded in the grayscale image stated, the camera and plane template distance are d millimeters, then sit at the right angle Camera coordinates described in mark system are (m/2, n/2, d*r);
In the grayscale image, EkIndicate the gray matrix of kth grayscale image, PijI-th row in grayscale image described in indicating Coordinate of the pixel of jth column in the rectangular coordinate system,Indicate k-th of light source the i-th row into the grayscale image The direction vector of the pixel of j column,The pixel of the i-th row jth column is right on the plane template in grayscale image described in indicating Surface normal of the point answered in the rectangular coordinate system;It is anti-when the plane template according to Lambert's law of reflection Penetrate light be diffusing reflection when, for its surface any point, there is following equation:
Solving equation can getAnd then solve the gradient at any point on the plane template surface;To gradient into Row integral can calculate the z coordinate at any point on the plane template surface, that is, restore first areal model.
The center of the light source group is overlapped with optimized migration coordinate.
The utility model has the advantages that passing through built-in three the present invention provides a kind of light source position calibration method of three-dimensional reconstruction apparatus Algorithm for reconstructing is tieed up, the light source position parameter in adjustment algorithm utilizes one group shot using plane template as object in shooting link Photo carries out three-dimensional reconstruction to plane template, and reconstructed results are fitted to plane and calculate the difference between reconstructed results and plane It is different, determine the best light source location parameter, can influence of the error to reconstructed results effectively in correcting device installation process, improve The quality of three-dimensional reconstruction.
Detailed description of the invention
Fig. 1 is the mechanical structure schematic diagram of the three-dimensional reconstruction apparatus for light source position calibration of the embodiment of the present application;
Drawing reference numeral explanation:
Plane template 1, camera 2, light source 1, light source 24, light source 35, light source 46.
Specific embodiment
Present invention is further described in detail with specific embodiment with reference to the accompanying drawing:
The present invention provides a kind of light source position calibration method of three-dimensional reconstruction apparatus, including light source group, camera, controller, The light source position calibration of plane template and image processor, provided three-dimensional reconstruction apparatus includes three links, , can be by built-in three-dimensional reconstruction algorithm under operation link, light source position parameter in adjustment algorithm, using in shooting ring Section carries out three-dimensional reconstruction to plane template using one group of photo that plane template is shot as object, determines best light by reconstructed results Source position parameter can effectively improve the quality of three-dimensional reconstruction.With reference to the accompanying drawing, to the specific embodiment party of the embodiment of the present application Formula is described in further detail.
Refering to what is shown in Fig. 1, the application mechanical structure is as follows, including plane template 1, and camera 2, light source 1, light source 24, light Source 35, light source 46.
The specific method is as follows for a kind of light source position calibration method of three-dimensional reconstruction apparatus of the present invention, and described device includes light source Group, camera, controller, plane template and image processor, it is characterised in that: the working condition of described device includes shooting ring Section prepares link and operation link;
It shoots under link:
Each light source under shooting link inside controller control light source group is successively lighted, and is stood after each light source igniting Carve the plane template that control camera shooting is placed in front of the light source group and the camera, one group of photograph of acquisition Piece is known as the first flat image;
Prepare under link:
Prepare using plane is x-y plane where first flat image under link, with first flat image The upper left corner is that origin establishes three-dimensional cartesian coordinate system;In the suitable detection step-length of image processor setting, along x, y-axis side The detection grid of (x, y) plane is parallel to foundation, it is characterised in that neighboring lattice points spacing is the detection step-length, described For the z-axis of three-dimensional cartesian coordinate system by wherein one of a certain lattice point, the camera position is coplanar with the detection grid, and And projection of the detection grid to z=0 plane is entirely located within first plan view image;
Under operation link:
(x, y) coordinate of offset coordinates is successively set as each in the detection grid by image processor under operation link The z coordinate of the offset coordinates is set as camera at a distance from the plane template by (x, y) coordinate of a lattice point;According to Three-dimensional reconstruction algorithm and first flat image built in the image processor carry out the plane template Three-dimensional reconstruction obtains the first areal model;By the first areal model upright projection to x-y plane, and view field It is evenly dividing along x, y-axis as the Error Grid having a size of m*n;Have in first areal model with the Error Grid lattice point identical The set of point of (x, y) coordinate be denoted as first cloud;
First cloud is fitted to by image processing unit in the three-dimensional cartesian coordinate system under operation link One plane, referred to as the second plane.It is flat at a distance from second plane to calculate point all in first cloud Fang He, referred to as error coefficient;Compare the offset coordinates and is located at the error obtained when each lattice point in the detection grid Coefficient, recording error coefficient minimum value, the offset coordinates when error coefficient is minimized are denoted as most suitable coordinate;
After operation link if the detection step-length be greater than 2 pixels, by the detection grid with it is described Most suitable coordinate be overlapped lattice point distance be greater than detection step-length lattice point delete;The detection step-length is halved and described New lattice point is added in detection grid;The detection grid is characterized in that neighboring lattice points after being added to the lattice point Distance is detection step-length, and the detection grid area does not increase;Subsequent repetitive operation link;
If the most suitable coordinate is denoted as most preferably by the detection step-length less than 2 pixels after operation link Offset coordinates.
The above described is only a preferred embodiment of the present invention, being not the limit for making any other form to the present invention System, and made any modification or equivalent variations according to the technical essence of the invention, still fall within present invention model claimed It encloses.

Claims (9)

1. a kind of light source position calibration method of three-dimensional reconstruction apparatus, it is characterised in that: the three-dimensional reconstruction apparatus includes light source Group, camera (2), controller, plane template (1) and image processor, wherein camera (2) is located at centre, and light source group includes light Source one (3), light source two (4), light source three (5), light source four (6) are located at 4 sides of camera (2), and plane template (1) is located at camera (2) and the top of light source group;
The light source position calibration method of the three-dimensional reconstruction apparatus includes shooting link, prepares link and operation link;Shoot ring It is shot under section by camera, obtains flat image, in preparing link, the flat image of shooting is subjected to gray processing processing, is passed through Built-in three-dimensional reconstruction algorithm adjusts light source position parameter, utilizes one group shot using plane template as object in shooting link Photo carries out three-dimensional reconstruction to plane template, determines the best light source location parameter by reconstructed results;
The offset coordinates that operation link obtains when error coefficient is minimized are denoted as most suitable coordinate;If institute after operation link The detection step-length stated is greater than 2 pixels, then is greater than the lattice point distance being overlapped in the detection grid with the most suitable coordinate The lattice point for detecting step-length is deleted;The detection step-length is halved and adds new lattice point in the detection grid;It is described The distances of neighboring lattice points of the detection grid after being added to the lattice point be detection step-length, and the detection grid surface Product does not increase;Subsequent repetitive operation link;It, will be described if the detection step-length is less than 2 pixels after operation link Most suitable coordinate be denoted as optimized migration coordinate.
2. the light source position calibration method of three-dimensional reconstruction apparatus according to claim 1, it is characterised in that: the shooting Link are as follows: each light source inside controller control light source group is successively lighted, and controls camera at once after each light source igniting Shooting is placed in the plane template in front of the light source group and the camera, and one group of photo of acquisition is known as first Flat image.
3. the light source position calibration method of three-dimensional reconstruction apparatus according to claim 1, it is characterised in that: the preparation Link is established three-dimensional using plane where first flat image as x-y plane using the first flat image upper left corner as origin Rectangular coordinate system;In the image processor setting detection step-length, along x, the inspection for being parallel to (x, y) plane is established in y-axis direction Survey grid lattice, neighboring lattice points spacing are the detection step-length, and the z-axis of the three-dimensional cartesian coordinate system is by wherein a certain lattice point One of, the camera position detection grid coplanar and described with the detection grid is entirely located in the projection of z=0 plane Within first plan view image.
4. the light source position calibration method of three-dimensional reconstruction apparatus according to claim 1, it is characterised in that: the operation Under link, image processor by (x, y) coordinate of offset coordinates be successively set as each lattice point in the detection grid (x, The z coordinate of the offset coordinates is set as camera at a distance from the plane template by y) coordinate;At the image It manages three-dimensional reconstruction algorithm and first flat image built in device and three-dimensional reconstruction is carried out to the plane template, obtain First areal model;By the first areal model upright projection to x-y plane, and view field is uniformly drawn along x, y-axis It is divided into the Error Grid having a size of m*n;There is identical (x, y) coordinate with the Error Grid lattice point in first areal model The set of point is denoted as first cloud;
First cloud is fitted to one by image processing unit in the three-dimensional cartesian coordinate system under operation link Plane, referred to as the second plane;Quadratic sum of the point all in first cloud at a distance from second plane is calculated, Referred to as error coefficient;Compare the offset coordinates and be located at the error coefficient obtained when each lattice point in the detection grid, Recording error coefficient minimum value, the offset coordinates when error coefficient is minimized are denoted as most suitable coordinate.
5. the light source position calibration method of three-dimensional reconstruction apparatus according to claim 1, it is characterised in that: the light source Group includes 4 light sources, is mounted on the midpoint on 4 sides of the square that side length is s;The camera (2) be mounted on it is described just Square central and its optical axis direction is perpendicular to the square;When shooting, each light source has and at only one In illuminating state;The brightness of each light source is identical and distance to each other can be measured accurately.
6. the light source position calibration method of three-dimensional reconstruction apparatus according to claim 1, it is characterised in that: the image Processing unit passes through the distance between light source in the grayscale information in first plan view image, the light source group, described Camera coordinate and its first areal model is calculated with the distance between the plane template.
7. the light source position calibration method of three-dimensional reconstruction apparatus according to claim 1, it is characterised in that: described first Flat image includes 4 pictures, will obtain 4 grayscale images, same position in 4 grayscale images after the 4 picture gray processings The pixel set has corresponded to the same point in areal model;If the grayscale image is having a size of m*n pixel, left with the grayscale image The pixel at upper angle is origin, is horizontally to the right y-axis direction, is vertically downward x-axis direction, is z towards the direction of the camera Axis positive direction establishes rectangular coordinate system;It is located at 1 millimeter in the plane template of length and corresponds to r picture in the grayscale image Element, the camera and plane template distance are d millimeters, then the camera coordinates described in the rectangular coordinate system For (m/2, n/2, d*r).
8. the light source position calibration method of three-dimensional reconstruction apparatus according to claim 1, it is characterised in that: the gray scale In figure, EkIndicate the gray matrix of kth grayscale image, PijThe pixel of the i-th row jth column is described in grayscale image described in indicating Coordinate in rectangular coordinate system,Indicate k-th of light source into the grayscale image the i-th row jth arrange pixel direction to Amount,Indicate the pixels of the i-th row jth column in the grayscale image on the plane template corresponding point described straight Surface normal in angular coordinate system;It is right when the reflected light of the plane template is diffusing reflection according to Lambert's law of reflection In its surface any point, there is following equation:
Solving equation can getAnd then solve the gradient at any point on the plane template surface;Gradient is accumulated Divide the z coordinate that can calculate any point on the plane template surface, that is, restores first areal model.
9. the light source position calibration method of three-dimensional reconstruction apparatus according to claim 1, it is characterised in that: the light source The center of group is overlapped with optimized migration coordinate.
CN201810507975.1A 2018-05-24 2018-05-24 Light source position calibration method of three-dimensional reconstruction device Expired - Fee Related CN109059800B (en)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020131559A1 (en) * 2001-03-13 2002-09-19 Laurent Launay Method of calibration for reconstructing three-dimensional models from images obtained by tomography
JP2014112043A (en) * 2012-12-05 2014-06-19 Ihi Corp Stereoscopic shape recognition device and light source position estimation method for stereoscopic shape recognition device
CN107194881A (en) * 2017-03-23 2017-09-22 南京汇川图像视觉技术有限公司 A kind of removal image reflex reflector and method based on photometric stereo
CN107657604A (en) * 2017-09-06 2018-02-02 西安交通大学 A kind of polishing scratch three-dimensional appearance original position acquisition methods based near field non-standard light source
CN107677216A (en) * 2017-09-06 2018-02-09 西安交通大学 A kind of multiple abrasive particle three-dimensional appearance synchronous obtaining methods based on photometric stereo vision
CN207365904U (en) * 2017-06-01 2018-05-15 深度创新科技(深圳)有限公司 Three-dimensional reconstruction apparatus and equipment

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20020131559A1 (en) * 2001-03-13 2002-09-19 Laurent Launay Method of calibration for reconstructing three-dimensional models from images obtained by tomography
JP2014112043A (en) * 2012-12-05 2014-06-19 Ihi Corp Stereoscopic shape recognition device and light source position estimation method for stereoscopic shape recognition device
CN107194881A (en) * 2017-03-23 2017-09-22 南京汇川图像视觉技术有限公司 A kind of removal image reflex reflector and method based on photometric stereo
CN207365904U (en) * 2017-06-01 2018-05-15 深度创新科技(深圳)有限公司 Three-dimensional reconstruction apparatus and equipment
CN107657604A (en) * 2017-09-06 2018-02-02 西安交通大学 A kind of polishing scratch three-dimensional appearance original position acquisition methods based near field non-standard light source
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