WO2021022934A1

WO2021022934A1 - Passive millimeter wave/terahertz imaging technology-based three-dimensional imaging method

Info

Publication number: WO2021022934A1
Application number: PCT/CN2020/098435
Authority: WO
Inventors: 侯丽伟; 潘鸣; 谢巍; 袁毅; 孙义兴; 黄晓锋; 周景石; 韩承英
Original assignee: 上海亨临光电科技有限公司; 江苏亨通太赫兹技术有限公司
Priority date: 2019-08-05
Filing date: 2020-06-28
Publication date: 2021-02-11
Also published as: CN110411375B; CN110411375A

Abstract

A passive millimeter wave/terahertz imaging technology-based three-dimensional imaging method, comprising: separately imaging the same target by two identical passive millimeter wave/terahertz imaging systems (1, 2), using an image registration technology to obtain position information of the same target point in images of the two imaging systems (1, 2), and calculating a three-dimensional coordinate point P(x, y, z) by means of a three-dimensional coordinate calculation formula by combining the mounting distance between the two imaging systems (1, 2) and angle information thereof, so as to obtain depth information of the target. The method achieves three-dimensional imaging of the target by the passive millimeter wave/terahertz imaging systems, and makes the recognition of a target object more accurate.

Description

A three-dimensional imaging method based on passive millimeter wave/terahertz imaging technology

Technical field

The invention relates to the technical field of millimeter wave/terahertz imaging, in particular to a three-dimensional imaging method based on passive millimeter wave/terahertz imaging technology.

Background technique

The existing passive imaging technology of millimeter wave/terahertz imaging systems can only obtain two-dimensional information of the imaged target, but cannot obtain depth information. Therefore, it cannot perform three-dimensional imaging of the target. However, when only two-dimensional information is used for imaging, In the case where the depth (thickness) information of the object cannot be obtained, it is easy to cause misjudgment in the identification of the object.

Summary of the invention

In view of the above problems, the present invention provides a three-dimensional imaging method based on passive millimeter wave/terahertz imaging technology, which enables the passive millimeter wave/terahertz imaging system to achieve three-dimensional imaging of targets and improve the accuracy of object recognition.

The technical solution is as follows: It is characterized by:

It includes the following steps:

S1. Image the same target through two passive millimeter-wave/terahertz imaging systems respectively to obtain two images, denoted as images imgI and imgII, and the image sizes of the images imgI and imgII are both M rows and N columns, M Is the total number of rows of the imaging system image, and N is the total number of columns of the imaging system image;

S2. Using image registration technology, search for the (k, 1) point paired with the (i, j) point in the image imgI in the image imgII, where (i, j) represents the i-th row and j-th column of the image imgI Pixel, (k, 1) represents the pixel in row k and column 1 of image imgII, where i=1, 2,...M, j=1, 2,...N, k=1, 2 ,...M,1=1,2,...N;

S3. The three-dimensional coordinate point of the target is denoted as P(x, y, z), and the positions of the three-dimensional coordinate point P(x, y, z) in the images imgI and imgII formed by the two imaging systems are respectively (i, j), (k, 1), converted from (i, j), (k, 1) to the offset of the three-dimensional coordinate point P (x, y, z) on the image plane of the two imaging systems (h1, v1) , (H2, v2) formula, and from (h1, v1), (h2, v2) to calculate the three-dimensional coordinate point P (x, y, z) coordinates are as follows:

Wherein, f is the distance from the optical center of the imaging system to its image plane, b is the length of the line between the optical centers of the two imaging systems; θ is the angle between the line of sight directions of the two imaging systems ；

Δx and Δy are the horizontal and vertical dimensions corresponding to each pixel of the imaging system;

S4. Repeat the steps S2 and S3 for all paired points to calculate the three-dimensional coordinate points, so as to achieve the acquisition of the three-dimensional image of the target.

Its further features are:

The two imaging systems are divided into imaging system I and imaging system II. The imaging system I and imaging system II are symmetrically inclined, and the optical centers O ₁ and O _{2 of} the imaging system I and imaging system II are connected as Baseline; the value range of the angle θ at which the line of sight directions of the imaging system I and the imaging system II intersect is 0°≤θ<180°; the optical centers O ₁ and O _{2 of} the imaging system I and the imaging system II are respectively The distance to the corresponding image plane is the same;

The three-dimensional coordinate axis is determined by taking the center of the baseline as the origin O, the direction of the origin pointing to the imaging system II as the X axis, and the direction perpendicular to the baseline as the Z axis. A rectangular coordinate system is established according to the right-hand system, perpendicular to the paper surface. The inner direction is the Y axis;

The step S1 also includes that before the imaging system is used, the optical center of the corresponding imaging system is projected on the upper surface of the imaging system along the optical axis, and the light is made by scribing or installing auxiliary brackets. Heart mark; Make two sight marks on the surface of the imaging system by scribing so that the line of the two sight marks is parallel to the line of sight of the imaging system.

The beneficial effect of the present invention is that it uses two identical passive millimeter wave/terahertz imaging systems to image the same target separately, and uses image registration technology to obtain the position information of the same target point in the images of the two imaging systems. The installation distance and angle information between the two imaging systems are calculated through the three-dimensional coordinate calculation formula to calculate the three-dimensional coordinate points, so that the depth information of the target can be obtained, and the passive millimeter wave/terahertz imaging system can realize the three-dimensional imaging of the target. Object recognition is more accurate.

Description of the drawings

Figure 1 is a schematic diagram of the imaging arrangement of the present invention.

detailed description

As shown in Figure 1, a three-dimensional imaging method based on passive millimeter wave/terahertz imaging technology includes the following steps:

S1. Image the same target through two passive millimeter-wave/terahertz imaging systems, respectively, to obtain two images, denoted as images imgI and imgII, and the image sizes of images imgI and imgII are both M rows and N columns, and M is imaging The total number of rows of the system image, N is the total number of columns of the imaging system image;

Wherein, step S1 also includes, before the imaging system is used, marking the optical center by scribing or installing an auxiliary bracket at the projection of the optical center of the corresponding imaging system along the optical axis on the upper surface of the imaging system; Make two line of sight marks on the surface by scribing so that the line of the two line of sight marks is parallel to the line of sight of the corresponding imaging system. You can mark the line of sight on the upper surface of the imaging system, or mark the line of sight on the lower surface. Both surfaces can be marked with the line of sight, and the line of sight marks are generally located at the front and back of the device. For example, mark the line of sight on the front and back of the upper surface of the imaging system. The line of the two line of sight marks and the corresponding imaging The line of sight of the system is parallel; the lower surface of the imaging system is marked by the same method as described above; and the marks made above are used to assist in the measurement of the length b of the baseline and the included angle θ. Preferably, the length b of the baseline is measured The measurement uses the line of sight mark on the lower surface, and the measurement of the included angle θ can use the line of sight mark on the upper surface.

S2. Using image registration technology, search for the (k, 1) point paired with the (i, j) point in the image imgI in the image imgII, where (i, j) represents the i-th row and j-th column of the image imgI Pixel, (k, l) represents the pixel in row k and column 1 of image imgII, where i=1, 2,...M, j=1, 2,...N, k=1, 2 ,...M, I=1, 2,...N;

Among them, the point (i, j) in the image imgI and the point (k, l) in the image imgII are paired points, that is to say, the scene point corresponding to the point (i, j) in the image imgI is located in the image imgII (k, l) point;

S3. The three-dimensional coordinate point of the target is marked as P(x, y, z), and the position of the three-dimensional coordinate point P(x, y, z) in the images imgI and imgII formed by the two imaging systems are respectively (i, j) , (K, l), converted from (i, j), (k, 1) to the offset of the three-dimensional coordinate point P (x, y, z) on the image plane of the two imaging systems (h1, v1), ( h2, v2), and from (h1, v1), (h2, v2), the three-dimensional coordinate point P(x, y, z) is calculated as follows:

Among them, f is the distance from the optical center of the imaging system to its image plane, b is the length of the line between the optical centers of the two imaging systems; θ is the angle between the line of sight directions of the two imaging systems;

S4. Repeat steps S2 and S3 for all paired points to calculate three-dimensional coordinate points, so as to obtain a three-dimensional image of the target.

The two imaging systems are divided into imaging system I1 and imaging system II2, imaging system I1 and imaging system II2 are symmetrically inclined. The optical centers of imaging system I1 and imaging system II2 are respectively denoted as O ₁ and O ₂ , imaging system I1 and imaging system The line connecting the optical centers O ₁ and O _{2 of} II2 is used as the baseline; the value range of the angle θ at which the sight directions of the imaging system I1 and the imaging system II2 intersect is 0°≤θ<180°; the imaging system I1 and the imaging system II2 are The same, therefore, the distance f from the optical centers O ₁ and O _{2 of the} imaging system I1 and the imaging system II2 to the corresponding image plane is the same.

In step S3, the three-dimensional coordinate axis of the three-dimensional coordinate point is determined by taking the center of the baseline as the origin O, the direction of the origin O pointing to the imaging system II2 as the X axis, and the direction perpendicular to the baseline as the Z axis, and establishing a rectangular coordinate system based on the right-handed system. The direction perpendicular to the paper surface is the Y axis.

Among them, after the imaging system I1 and the imaging system II2 are installed according to Figure 1, when the imaging system I1 and the imaging system II2 are used for the first time or when the positional relationship of the imaging system II2 changes, the imaging system I1 and the imaging system II2 need to be calibrated, that is, measurement The length b of the baseline and the included angle θ, specifically, the measurement method of the length b of the baseline is to directly measure the distances of the optical center marks of the imaging system I1 and the imaging system II2 with a meter ruler and other length measuring tools; the measurement of the included angle θ The method is to draw or mark the center line of sight direction of the imaging system on the ground according to the line of sight mark on the imaging system, and measure the angle between the line of sight directions of imaging system I1 and imaging system II2 with a protractor, which is θ.

For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description, and therefore it is intended to fall within the claims. All changes within the meaning and scope of the equivalent elements of are included in the present invention. Any reference signs in the claims should not be regarded as limiting the claims involved.

In addition, it should be understood that although this specification is described in accordance with the implementation manners, not each implementation manner only contains an independent technical solution. This narration in the specification is only for clarity, and those skilled in the art should regard the specification as a whole The technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims

A three-dimensional imaging method based on passive millimeter wave/terahertz imaging technology, which is characterized in:

It includes the following steps:

S1. Image the same target through two passive millimeter wave/terahertz imaging systems, respectively, to obtain two images, denoted as images imgⅠ and imgⅡ, and the image sizes of the images imgⅠ and imgⅡ are M rows and N columns, M Is the total number of rows of the imaging system image, and N is the total number of columns of the imaging system image;

S2. Using image registration technology, search for the (k, l) point paired with the (i, j) point in the image imgⅠ in the image imgⅡ, where (i, j) represents the i-th row and j-th column of the image imgⅠ Pixel, (k,l) represents the pixel in the kth row and lth column of the image imgII, where i=1, 2,...M,j=1, 2,...N, k=1, 2,...M, l=1,2,...N;

S3. The three-dimensional coordinate point of the target is denoted as P(x,y,z), and the positions of the three-dimensional coordinate point P(x,y,z) in the images imgI and imgII formed by the two imaging systems are respectively (i, j), (k, l), converted from (i, j), (k, l) to the offset of the three-dimensional coordinate point P (x, y, z) on the image plane of the two imaging systems (h1, v1) , (H2, v2) formula, and from (h1, v1), (h2, v2) to calculate the three-dimensional coordinate point P (x, y, z) coordinates as follows:

Wherein, f is the distance from the optical center of the imaging system to its image plane, b is the length of the line between the optical centers of the two imaging systems; θ is the angle between the line of sight directions of the two imaging systems ；

Δx and Δy are the horizontal and vertical dimensions corresponding to each pixel of the imaging system;

S4. Repeat the steps S2 and S3 for all the paired points to calculate the three-dimensional coordinate points, thereby achieving the acquisition of the three-dimensional image of the target.
A three-dimensional imaging method based on passive millimeter wave/terahertz imaging technology according to claim 1, wherein the two imaging systems are divided into imaging system I and imaging system II, and imaging system I and imaging The system II is symmetrically inclined, and the line connecting the optical centers O 1 and O 2 of the imaging system I and the imaging system II is used as the baseline; the value range of the angle θ at which the line of sight directions of the imaging system I and the imaging system II intersect It is 0°≤θ<180°; the distances from the optical centers O 1 and O 2 of the imaging system I and the imaging system II to the corresponding image planes are the same.
A three-dimensional imaging method based on passive millimeter wave/terahertz imaging technology according to claim 2, wherein the three-dimensional coordinate axis is determined by taking the center of the baseline as the origin O, and the origin pointing to the imaging system II The direction of is the X axis, the direction perpendicular to the baseline is the Z axis, a rectangular coordinate system is established according to the right-hand system, and the direction perpendicular to the paper surface is the Y axis.
The 3D imaging method based on passive millimeter wave/terahertz imaging technology according to claim 1, characterized in that: said step S1 further comprises: before the imaging system is used, the light of the corresponding imaging system The optical center is marked on the projection of the upper surface of the imaging system along the optical axis by scribing or installing an auxiliary bracket; two sight marks are made on the surface of the imaging system by scribing so that two The line of the line of sight mark is parallel to the line of sight of the corresponding imaging system.