A method for eliminating jitter of pavement depth images captured by a line laser 3D camera

Abstract

The present invention discloses a method for eliminating jitter of pavement depth pictures captured by a line laser 3D camera. S1: Traverse each row of the depth picture, assuming it is the i-th row; S2: Read all w depth data of the i-th row to form an array a i , sort the array a i to obtain a new array a' i ; S3: The middle data of the array a' i forms a new array b i ; S4: Calculate the average value of the depth data of the array b i to obtain the average ground height dm i of the i-th row. Then b in is the depth data corresponding to the n-th element of the array b i ; S5: For the w elements of the array a i , subtract dm i from the depth data corresponding to each element to obtain a new array c i . Replace all the depth data of the i-th row of the original depth picture with the depth data included in the array c i ; S6: Repeat the above steps until all h rows are traversed. By using an algorithm to eliminate jitter, the operation is greatly simplified, and there is no need to install additional sensors, improving the efficiency.

Description

Technical Field

[0001] The present invention relates to the field of depth image jitter elimination, and particularly to a method for eliminating jitter of a pavement depth image captured by a line laser 3D camera. Background Art

[0002] A line laser 3D camera is a three-dimensional camera that, based on the principle of triangulation or structured light, captures the laser line information projected on the surface of an object by an image sensor, thereby reconstructing the contour information of the object surface.

[0003] In common factory applications, the laser emitter and the 3D camera are fixed. The object to be measured passes under the 3D camera on the conveyor belt at a stable speed. Since the 3D camera is fixed and the conveyor belt moves smoothly with little jitter, the depth measurement accuracy can even reach the micron level. However, in the shooting of pavement depth images, the image acquisition method has changed. The laser emitter and the 3D camera are fixed on a moving platform (vehicle or outdoor mobile robot) and move along the pavement to be photographed with the moving platform. The line laser is perpendicular to the advancing direction of the moving platform. Due to the inevitable self-jitter of the moving platform during travel, the depth image captured by the 3D camera undergoes data distortion. Among them, the up-and-down jitter of the moving platform perpendicular to the pavement has the greatest impact on the depth image because the jitter is directly superimposed on the data of the depth image, which has an adverse effect on automatic disease identification.

[0004] The existing method is to additionally install an accelerometer (or IMU, inertial navigation, etc., which essentially measure acceleration) on the 3D acquisition system. The accelerometer measures the acceleration distributed over time in the direction perpendicular to the pavement of the entire 3D acquisition system, and then performs a second integral on the acceleration to obtain the displacement distributed over time in the direction perpendicular to the pavement (i.e., the jitter interference). Each row on the captured depth image also corresponds to a specific time. Finally, the captured depth image is subtracted from the interpolated corresponding displacement to filter out the jitter. However, this method has certain defects. First, additional hardware needs to be installed, and the structural stiffness needs to be ensured to make the jitter of the sensor and the 3D camera exactly the same. Second, it takes two integrations of the acceleration to obtain the displacement change, and the cumulative error is large, affecting the accuracy of calculating the jitter displacement. After long-term research by the inventor, a method for eliminating jitter of a pavement depth image captured by a line laser 3D camera has been invented. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for eliminating jitter of a pavement depth image captured by a line laser 3D camera.

[0006] The purpose of the present invention is achieved by the following technical solutions: A method for eliminating jitter of a road depth image taken by a line laser 3D camera, assuming that the road depth image taken by the 3D camera has h rows and w columns, and the depth data corresponding to each pixel is d ij , where i represents the i-th row, j represents the j-th column, 1≤i≤h, 1≤j≤w, including the following steps:

[0007] S1: traverse each row of the depth image, assuming that the current row is the i-th row;

[0008] S2: Read all w depth data of row i and form an array a i , for array a i Sort the depth data from small to large to get a new array a' i ;

[0009] S3: intercept array a' i The middle data of the array is used to form a new array b i ;

[0010] S4: Find array b i The average ground height corresponding to the i-th row is obtained by averaging the depth data. Let the average ground height of this row be dm i ,but

[0011]

[0012] where b in is array b i The depth data corresponding to the nth element;

[0013] S5: array a i The depth data corresponding to each element is subtracted from dm i , get a new set of arrays c i , with array c i The included depth data replaces all the depth data in the i-th row of the original depth image;

[0014] S6: Repeat the above steps until all h rows are traversed, and a new depth image with jitter eliminated is obtained.

[0015] Preferably, the method for obtaining the middle data of S3 comprises the following steps:

[0016] A1: Assume that k data are taken from the middle segment, where 1<k<w;

[0017] A2: Order

[0018]

[0019] Then the array a'i Remove the first x pieces of data and the last y pieces of data, and the remaining k pieces of data can form b i 。

[0020] Preferably, n≤k and n≥1 in S4.

[0021] The present invention has the following advantages: By using an algorithm to eliminate jitter, the present invention greatly simplifies the operation and does not require additional sensors, thus improving the efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] None. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some but not all of the embodiments of the present invention. Generally, the components of the embodiments of the present invention described and illustrated herein can be arranged and designed in various different configurations.

[0024] Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.

[0025] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0026] It should be noted that: Similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0027] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the invention is usually placed during use, or the orientation or positional relationship commonly understood by those skilled in the art. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first", "second", etc. are only used for descriptive distinction and should not be construed as indicating or implying relative importance.

[0028] In the description of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0029] In this embodiment, a method for eliminating jitter of a pavement depth picture captured by a line laser 3D camera is provided. Assume that the pavement depth picture captured by the 3D camera has h rows and w columns, and the depth data corresponding to each pixel is d ij , where i represents the i-th row, j represents the j-th column, 1 ≤ i ≤ h, 1 ≤ j ≤ w, and the method includes the following steps:

[0030] S1: Traverse each row of the depth picture. Assume that the current row is the i-th row;

[0031] S2: Read all w depth data of the i-th row to form an array a i , and sort the array a i in ascending order of depth data to obtain a new array a'; i ;

[0032] S3: Intercept the middle data of the array a' i to form a new array b i ;

[0033] S4: Calculate the average value of the depth data of the array b i to obtain the average ground height corresponding to the i-th row. Let the average ground height of this row be dm i , then

[0034]

[0035] where b in is the depth data corresponding to the n-th element of the array b i ;

[0036] S5: Subtract dm i from the depth data corresponding to each of the w elements of the array a i to obtain a new array c i , and replace all the depth data of the i-th row of the original depth picture with the depth data included in the array c i ;

[0037] S6: Repeat the above steps until all h rows are traversed, and a new depth image after jitter elimination is obtained. By using an algorithm to eliminate jitter, the operation is greatly simplified, and no additional sensors are required, improving the efficiency.

[0038] Further, the method for obtaining the middle data in S3 includes the following steps:

[0039] A1: Assume that k data are taken in the middle section, where 1 < k < w. For example, k can be taken as w / 2;

[0040] A2: Let

[0041]

[0042] Then the array a' i Remove the first x data and the last y data, and the remaining k data can form b i .

[0043] Specifically, the purpose of taking the middle data is to eliminate the maximum and minimum values, so that the data can better reflect the true ground height.

[0044] Furthermore, in S4, n ≤ k and n ≥ 1.

[0045] Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for eliminating jitter of pavement depth images captured by a line laser 3D camera, characterized in that: Assume that the pavement depth image captured by the 3D camera has h rows and w columns, and the depth data corresponding to each pixel is d ij , where i represents the i-th row and j represents the j-th column, 1 ≤ i ≤ h, 1 ≤ j ≤ w, and it includes the following steps: S1: Traverse each row of the depth image, assuming the current is the i-th row; S2: Read all w depth data of the i-th row to form an array a i , for the array a i Sort the depth data in ascending order to obtain a new array a' i ; S3: intercept array a' i The middle data of the array is used to form a new array b i ; S4: Obtain the array b i Calculate the average of the depth data to obtain the average ground height corresponding to the i-th row, and set the average ground height of this row as dm i , then where b in is the depth data corresponding to the n-th element of the array b i ​ S5: For the w elements of array a i subtract dm from the depth data corresponding to each element i to obtain a new array c i Replace all the depth data in the i-th row of the original depth image with the depth data contained in array c i ; S6: Repeat the above steps until all h rows are traversed, that is, a new depth image after jitter elimination is obtained.

2. The method for eliminating jitter of pavement depth images captured by a line laser 3D camera according to claim 1, characterized in that: The method for obtaining the middle data in S3 includes the following steps: A1: Assume that k data are taken in the middle section, where 1 < k < w; A2: Let Then the array a' i Remove the first x data and the last y data, and the remaining k data can form b i .

3. The method for eliminating jitter of pavement depth images captured by a line laser 3D camera according to claim 2, characterized in that: n ≤ k and n ≥ 1 in S4.

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