Area measurement error evaluation method for multiband photoelectric imaging system

Abstract

The invention discloses a multi-band photoelectric imaging system area measurement error evaluation method. The method comprises the following steps: arranging multiband radiation sources at certain intervals in an array manner at a far working distance of a photoelectric imaging system, taking the multiband radiation sources as an observation target to carry out an area measurement error evaluation test of the photoelectric imaging system, and taking a projection area of the observation target on a vertical plane of an optical axis of the imaging system as a target area true value; and comparing with the target area measurement value of the photoelectric imaging system, and evaluating the area measurement error of the system. According to the characteristics of long working distance and large observation area of the photoelectric imaging system, the radiation source arrangement spacing can be adjusted, a large-size target array can be arranged, a measurable target area true value matched with the working distance of the imaging system can be constructed, effective evaluation can be carried out, the target radiation source cost is low, and the test is easy to operate; through reasonable arrangement of the multi-band array radiation sources, area measurement error evaluation under the requirement of multi-band multi-resolution detection can be met, the universality is very high, and the method has important significance.

Description

Technical Field

[0001] The invention belongs to the technical field of target photoelectric characteristic measurement, and in particular relates to an area measurement error evaluation method for a multi-band photoelectric imaging system. Background Art

[0002] Target area measurement and evaluation is an important part of data measurement and analysis of optoelectronic imaging systems. It is not only related to the measurement of indicators of cooperative targets such as shielding area, but also an important basis for authenticity identification and target classification of non-cooperative targets in the field of optoelectronic detection.

[0003] No literature has been found to elaborate on the area measurement error evaluation method of the optoelectronic imaging system: Li Yong et al. pointed out that the target radiation area is extracted and converted into the target area, but did not discuss the system area measurement error evaluation; Li Xin et al. mentioned that the target area index is determined based on the total number of pixels N, but did not involve the area index error evaluation (CN 118761211A); the target shielding area evaluation patents (CN 116187036 A and CN 115219460 A) also did not explain the system area measurement error evaluation method.

[0004] Comparison between theoretical true value and measured value is an important method for evaluating measurement error. For the area measurement error evaluation of the optoelectronic imaging system, the theoretical area true value can be calculated through geometric relationships based on the observed object with regular shape, and then compared with the measured area value to calculate the error.

[0005] Based on this idea, in order to realize the area measurement error evaluation of the optoelectronic imaging system, a regular-shaped surface source can be introduced as the observation object, and the target area true value and the measured value are compared to obtain the area measurement error. However, the optoelectronic imaging system has a long working distance and a large observation area. It is difficult and costly to prepare a surface source of corresponding large area size. In addition, the optoelectronic imaging system often covers multiple working bands such as visible light, short wave, medium wave, and long wave.

[0006] In order to solve the above problems, it is urgent to study an easy-to-implement, low-cost area measurement error evaluation method for optoelectronic imaging systems that is suitable for multi-band and long-distance operation, so as to provide an important reference for optoelectronic system performance evaluation and detection applications. Summary of the invention

[0007] The present invention discloses a method for evaluating the area measurement error of a multi-band photoelectric imaging system, which solves the technical problems existing in the above-mentioned prior art. The evaluation method is easy to implement and low in cost, and can be applied to the area measurement error evaluation of a multi-band and long-distance photoelectric imaging system, providing an important reference for the performance evaluation and detection application of the photoelectric system.

[0008] The present invention adopts the following technical solutions:

[0009] A method for evaluating the area measurement error of a multi-band optoelectronic imaging system is disclosed. At a long working distance of the optoelectronic imaging system, multi-band radiation sources are arranged in an array at a certain interval. These are used as observation targets to carry out an evaluation test of the area measurement error of the optoelectronic imaging system. The projection area of ​​the observed target on the plane perpendicular to the optical axis of the imaging system is taken as the true value of the target area, which is compared with the target area measurement value of the optoelectronic imaging system to evaluate the area measurement error of the system.

[0010] Furthermore, the method specifically comprises the following steps:

[0011] (1) According to the field of view angle α (°) and working distance R (m) of the optoelectronic imaging system, determine its linear field of view L at the working distance R FOV (m); the calculation formula is as follows:

[0012] L FOV =2R×tand(α / 2) (Formula 1)

[0013] Where tand is the tangent function;

[0014] (2) Select the test site;

[0015] (3) Determine the radiation source layout interval ΔL (m) and array specifications;

[0016] (4) Conduct imaging experiments and record imaging data;

[0017] (5) Select the radiation source array target and calculate the area measurement value S of the optoelectronic imaging system * ;

[0018] (6) calculating the projection area S of the radiation source array target selected in step (5) on the plane perpendicular to the optical axis of the imaging system;

[0019] (7) Calculate the area measurement error ε:

[0020] ε=|SS * | / S (Formula 7);

[0021] (8) Select different radiation source array targets, repeat steps (5) to (7) 3 to 5 times, and take the average value of the area measurement error as the final area measurement error of the optoelectronic imaging system in the working band;

[0022] (9) For a multi-band optoelectronic imaging system, a suitable radiation source array target is selected in combination with the imaging resolution of each working band, and steps (5) to (8) are repeated to obtain the area measurement error of each working band of the optoelectronic imaging system.

[0023] Furthermore, the specific operation method of step (2) is as follows:

[0024] Select two test sites with a distance of not less than the working distance R (m) between the ground or the ground and the slope; one of the ground is used to place the electro-optical imaging system to be evaluated, and the other ground or slope is used to lay out the radiation source; the width of the ground or slope used to lay out the radiation source is not less than γL FOV (m), where γ is the proportional coefficient of the radiation source occupying the image plane in the horizontal direction, and takes values ​​in the interval [1 / 3, 4 / 5]. The inclination angle between the radiation source layout plane and the ground is β(°), β∈[0°, 90°]. If the radiation source is arranged on the horizontal ground, β=0°; if the radiation source is arranged on a lifting rod perpendicular to the ground, β=90°; if the radiation source is arranged on a slope, β∈(0°, 90°).

[0025] Further: The specific operation method of step (3) is as follows:

[0026] The radiation sources are arranged in an n×n array, where n can be 3, 5, 7, 9, etc. The radiation source arrangement interval ΔL is determined according to the following formula:

[0027] ΔL=γ×L FOV / (n-1) (Formula 2)

[0028] For a multi-band imaging optoelectronic system, the linear field of view L of each band at the working distance R is integrated. FOV , reasonably select the radiation source array specification n, determine the radiation source layout interval ΔL, which can meet the area measurement error evaluation under the multi-band and multi-resolution detection requirements; if the line field of view L of different working bands of the multi-band imaging optoelectronic system FOV If the values ​​are different, the corresponding γ values ​​will also be different, and it is necessary to avoid the situation where the γ value is too large or too small; γ takes values ​​in the interval [1 / 3, 4 / 5]. When the γ value is greater than 4 / 5, it is considered to be too large, and when the γ value is less than 1 / 3, it is considered to be too small.

[0029] Furthermore, the specific steps of step (4) are as follows:

[0030] (4.1) Arrange the radiation source array and set up the optoelectronic imaging system in the test site selected in step (2) according to the radiation source arrangement spacing and array specifications determined in step (3);

[0031] (4.2) Set the working field angle of the optoelectronic imaging system, adjust the pitch angle θ(°) of the system turntable or tripod bracket, align the optoelectronic imaging system with the radiation source for clear imaging, ensure that the radiation sources in the same row are located on the same row of the system image plane, and save the imaging data, where θ is based on the horizontal plane, θ∈[-90°, 90°].

[0032] Furthermore, the specific steps of step (5) are as follows:

[0033] (5.1) In the n×n radiation source array image of the single-band image plane of the optoelectronic imaging system, select a suitable m×m radiation source array target, where m≤n;

[0034] (5.2) Record the upper left corner (X) of the m×m radiation source array target on the radiation source image plane LT ,Y LT ), Upper Right (X RT ,Y RT ), Lower Left (X LD ,Y LD ), Lower Right (X RD ,Y RD ) four imaging positions;

[0035] (5.3) Calculate the number of pixels N of the radiation source on the image plane of the photoelectric imaging system. The calculation formula is as follows:

[0036] N={(X RT -X LT )+(X RD -X LD )}×(Y LD -Y LT ) / 2 (Formula 3);

[0037] (5.4) Calculate the area measurement value S of the optoelectronic imaging system for the area enclosed by the edge connection line of the radiation source array target selected in step (5.1) * (m 2 ):

[0038]

[0039] Furthermore, the specific steps of step (6) are as follows:

[0040] (6.1) Calculate the area S of the radiation source array target on the layout plane 0 (m 2 ):

[0041] S 0 =((m-1)×ΔL) 2 =(γ×L FOV ×(m-1) / (n-1)) 2 (Formula 5);

[0042] (6.2) Calculate the projection area S (m 2 ):

[0043] S=S 0 ×cosd(θ+β) (Formula 6)

[0044] Where cosd is the cosine function.

[0045] The beneficial effects of the present invention are that according to the characteristics of the optoelectronic imaging system with a long working distance and a large observation area, the spacing of the radiation sources can be adjusted, a large-size target array can be arranged, a measurable target area true value matching the working distance of the imaging system can be constructed, and an effective evaluation can be carried out. The target radiation source has a low cost and the test is easy to operate. By reasonably arranging the multi-band n×n array radiation source, the area measurement error evaluation under the multi-band and multi-resolution detection requirements can be met. It has strong universality and can provide an important reference basis for the performance evaluation and detection application of the optoelectronic system. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a block diagram of the experimental principle of the area measurement error evaluation of a multi-band long-distance optoelectronic imaging system of the present invention. In the figure, 1 represents the optoelectronic imaging system to be evaluated; 2 is the ground on which the optoelectronic imaging system is placed; 3 is the multi-band radiation source, which is R (m) away from the optoelectronic imaging system; 4 is the inclined plane on which the radiation source array is placed, which can form a certain inclination angle β with the ground; 5 is the optical axis direction of the optoelectronic imaging system to be evaluated, which can form a certain inclination angle θ with the ground; 6 is the projection position of the radiation source in the upper left corner of the radiation source array on the vertical plane of the optical axis of the optoelectronic system at that location, corresponding to the upper left corner (X LT ,Y LT ) imaging position; 7 is the projection position of the radiation source in the upper right corner of the radiation source array on the vertical plane of the optical axis of the optoelectronic system at that location, corresponding to the upper right corner (X RT ,Y RT ) imaging position; 8 is the projection position of the radiation source at the lower left corner of the radiation source array on the vertical plane of the optical axis of the optoelectronic system at that location, corresponding to the lower left corner (X LD ,Y LD ) imaging position; 9 is the projection position of the radiation source at the lower right corner of the radiation source array on the vertical plane of the optical axis of the optoelectronic system at that location, corresponding to the lower right corner (X RD ,Y RD ) imaging position.

[0047] Figure 2 The imaging diagram of the radiation source array target by the multi-band optoelectronic imaging system is, from left to right, the visible light imaging diagram (night imaging), short wave imaging diagram, medium wave imaging diagram, and long wave imaging diagram. The specification of the radiation source array in the figure is 3×5. By performing an imaging experiment on a radiation source array target of a certain specification, the multi-band radiation source array target image shown in the figure is obtained. By using the method of the present invention, the area measurement error of each working band of the multi-band optoelectronic imaging system can be evaluated. DETAILED DESCRIPTION

[0048] The specific implementation of the present invention is further described in detail below with reference to the accompanying drawings:

[0049] The present invention provides a method for evaluating the area measurement error of a multi-band optoelectronic imaging system. Multi-band radiation sources are arranged in an array at a certain interval far away from the working distance of the optoelectronic imaging system, and the multi-band radiation sources are used as observation targets to carry out an evaluation test of the area measurement error of the optoelectronic imaging system. The projection area of ​​the observed target on the plane vertical to the optical axis of the imaging system is taken as the true value of the target area, which is compared with the target area measurement value of the optoelectronic imaging system to evaluate the area measurement error of the system.

[0050] Figure 1 The figure shows a block diagram of the experimental principle of the area measurement error evaluation of a multi-band long-distance photoelectric imaging system of the present invention. Referring to the block diagram of the experimental principle, the specific implementation process of the present invention can be roughly divided into the following steps:

[0051] (1) According to the field of view angle α (°) and working distance R (m) of the optoelectronic imaging system, determine its linear field of view L at the working distance R FOV (m). The calculation formula is as follows:

[0052] L FOV =2R×tand(α / 2) (Formula 1)

[0053] Where tand is the tangent function.

[0054] (2) Select the test site. The specific operation method is as follows:

[0055] Select two test sites with a distance of not less than the working distance R (m) between the ground or the ground and the inclined plane. One of the ground is used to place the electro-optical imaging system to be evaluated, and the other ground or inclined plane is used to lay out the radiation source. The width of the ground or inclined plane used to lay out the radiation source is not less than γL FOV (m), where γ is the ratio coefficient of the radiation source occupying the image plane in the horizontal direction, and takes values ​​in the interval [1 / 3, 4 / 5]. The inclination angle between the radiation source layout plane and the ground is β(°), β∈[0°, 90°]. If the radiation source is arranged on the horizontal ground, β=0°; if the radiation source is arranged on a lifting rod perpendicular to the ground, β=90°; if the radiation source is arranged on a slope, β∈(0°, 90°).

[0056] (3) Determine the radiation source layout interval ΔL (m) and array specifications. The specific operation method is as follows:

[0057] The radiation sources are arranged in an n×n array, where n can be 3, 5, 7, 9, etc. The radiation source arrangement interval ΔL is determined according to the following formula:

[0058] ΔL=γ×L FOV / (n-1) (Formula 2)

[0059] For a multi-band imaging optoelectronic system, the linear field of view L of each band at the working distance R is integrated. FOV , reasonably select the radiation source array specification n, determine the radiation source layout interval ΔL, can meet the area measurement error evaluation under the multi-band multi-resolution detection requirements. If the line field of view L of different working bands of the multi-band imaging optoelectronic system FOV If the values ​​are different, the corresponding γ values ​​will also be different, and it is necessary to avoid the situation where the γ value is too large or too small; γ takes values ​​in the interval [1 / 3, 4 / 5]. When the γ value is greater than 4 / 5, it is considered to be too large, and when the γ value is less than 1 / 3, it is considered to be too small.

[0060] (4) Conduct imaging tests and record imaging data. The specific steps are as follows:

[0061] (4.1) Arrange the radiation source array and set up the optoelectronic imaging system in the test site selected in step (2) according to the radiation source arrangement spacing and array specifications determined in step (3);

[0062] (4.2) Set the working field angle of the optoelectronic imaging system, adjust the pitch angle θ(°) of the system turntable or tripod bracket, align the optoelectronic imaging system with the radiation source for clear imaging, ensure that the radiation sources in the same row are located on the same row of the system image plane, and save the imaging data, where θ is based on the horizontal plane, θ∈[-90°, 90°].

[0063] (5) Calculate the area measurement value S of the photoelectric imaging system * The specific steps are as follows:

[0064] (5.1) In the n×n radiation source array image of the single-band image plane of the optoelectronic imaging system, select a suitable m×m radiation source array target, where m≤n;

[0065] (5.2) Record the upper left corner (X) of the m×m radiation source array target on the radiation source image plane LT ,Y LT ), Upper Right (X RT ,Y RT ), Lower Left (X LD ,Y LD ), Lower Right (X RD ,Y RD ) four imaging positions;

[0066] (5.3) Calculate the number of pixels N of the radiation source on the image plane of the photoelectric imaging system. The calculation formula is as follows:

[0067] N={(X RT -X LT )+(X RD -X LD )}×(Y LD -Y LT) / 2 (Formula 3);

[0068] (5.4) Calculate the area measurement value S of the optoelectronic imaging system for the area enclosed by the edge connection line of the radiation source array target selected in step (5.1) * (m 2 ):

[0069]

[0070] (6) Calculate the projection area S of the radiation source array target selected in step (5.1) on the plane perpendicular to the optical axis of the imaging system. The specific steps are as follows:

[0071] (6.1) Calculate the area S of the radiation source array target on the layout plane 0 (m 2 ):

[0072] S 0 =((m-1)×ΔL) 2 =(γ×L FOV ×(m-1) / (n-1)) 2 (Formula 5);

[0073] (6.2) Calculate the projection area S (m 2 ):

[0074] S=S 0 ×cosd(θ+β) (Formula 6)

[0075] Where cosd is the cosine function.

[0076] (7) Calculate the area measurement error ε.

[0077] ε=|SS * | / S(Formula 7).

[0078] (8) Select different radiation source array targets, repeat steps (5) to (7) 3 to 5 times, and take the average value of the area measurement error as the final area measurement error of the optoelectronic imaging system in this working band.

[0079] (9) For a multi-band optoelectronic imaging system, a suitable radiation source array target is selected in combination with the imaging resolution of each working band, and steps (5) to (8) are repeated to obtain the area measurement error of each working band of the optoelectronic imaging system.

Claims

1. A method for evaluating area measurement error of a multi-band optoelectronic imaging system, characterized in that: At a distance from the working distance of the optoelectronic imaging system, multi-band radiation sources are arranged in an array at a certain interval. They are used as observation targets to carry out the area measurement error evaluation test of the optoelectronic imaging system. The projection area of ​​the observed target on the plane perpendicular to the optical axis of the imaging system is taken as the true value of the target area. It is compared with the target area measurement value of the optoelectronic imaging system to evaluate the system area measurement error.

2. The method for evaluating area measurement error of a multi-band optoelectronic imaging system according to claim 1, characterized in that: The specific steps include: (1) According to the field of view angle α (°) and working distance R (m) of the optoelectronic imaging system, determine its linear field of view L at the working distance R FOV (m); the calculation formula is as follows: L FOV =2R×tand(α / 2) (Formula 1) Where tand is the tangent function; (2) Select the test site; (3) Determine the radiation source layout interval ΔL (m) and array specifications; (4) Conduct imaging experiments and record imaging data; (5) Select the radiation source array target and calculate the area measurement value S of the optoelectronic imaging system * ; (6) calculating the projection area S of the radiation source array target selected in step (5) on the plane perpendicular to the optical axis of the imaging system; (7) Calculate the area measurement error ε: ε=|SS * | / S (Formula 7); (8) Select different radiation source array targets, repeat steps (5) to (7) 3 to 5 times, and take the average value of the area measurement error as the final area measurement error of the optoelectronic imaging system in the working band; (9) For a multi-band optoelectronic imaging system, a suitable radiation source array target is selected in combination with the imaging resolution of each working band, and steps (5) to (8) are repeated to obtain the area measurement error of each working band of the optoelectronic imaging system.

3. The method for evaluating area measurement error of a multi-band optoelectronic imaging system according to claim 2, characterized in that: The specific operation method of step (2) is as follows: Select two test sites with a distance of not less than the working distance R (m) between the ground or the ground and the slope; one of the ground is used to place the electro-optical imaging system to be evaluated, and the other ground or slope is used to lay out the radiation source; the width of the ground or slope used to lay out the radiation source is not less than γL FOV (m), where γ is the proportional coefficient of the radiation source occupying the image plane in the horizontal direction, and takes values ​​in the interval [1 / 3, 4 / 5]. The inclination angle between the radiation source layout plane and the ground is β(°), β∈[0°, 90°]. If the radiation source is arranged on the horizontal ground, β=0°; if the radiation source is arranged on a lifting rod perpendicular to the ground, β=90°; if the radiation source is arranged on a slope, β∈(0°, 90°).

4. The method for evaluating area measurement error of a multi-band optoelectronic imaging system according to claim 2, characterized in that: The specific operation method of step (3) is as follows: The radiation sources are arranged in an n×n array, where n can be 3, 5, 7, 9, etc. The radiation source arrangement interval ΔL is determined according to the following formula: ΔL=γ×L FOV / (n-1) (Formula 2) For a multi-band imaging optoelectronic system, the linear field of view L of each band at the working distance R is integrated. FOV , reasonably select the radiation source array specification n, determine the radiation source layout interval ΔL, which can meet the area measurement error evaluation under the multi-band and multi-resolution detection requirements; if the line field of view L of different working bands of the multi-band imaging optoelectronic system FOV If the values ​​are different, the corresponding γ values ​​will also be different, and it is necessary to avoid the situation where the γ value is too large or too small; γ takes values ​​in the interval [1 / 3, 4 / 5]. When the γ value is greater than 4 / 5, it is considered to be too large, and when the γ value is less than 1 / 3, it is considered to be too small.

5. The method for evaluating area measurement error of a multi-band optoelectronic imaging system according to claim 2, characterized in that: The specific steps of step (4) are as follows: (4.1) Arrange the radiation source array and set up the optoelectronic imaging system in the test site selected in step (2) according to the radiation source arrangement spacing and array specifications determined in step (3); (4.2) Set the working field angle of the optoelectronic imaging system, adjust the pitch angle θ(°) of the system turntable or tripod bracket, align the optoelectronic imaging system with the radiation source for clear imaging, ensure that the radiation sources in the same row are located on the same row of the system image plane, and save the imaging data, where θ is based on the horizontal plane, θ∈[-90°, 90°].

6. The method for evaluating area measurement error of a multi-band optoelectronic imaging system according to claim 2, characterized in that: The specific steps of step (5) are as follows: (5.1) In the n×n radiation source array image of the single-band image plane of the optoelectronic imaging system, select a suitable m×m radiation source array target, where m≤n; (5.2) Record the upper left corner (X) of the m×m radiation source array target on the radiation source image plane LT ,Y LT ), Upper Right (X RT ,Y RT ), Lower Left (X LD ,Y LD ), Lower Right (X RD ,Y RD ) four imaging positions; (5.3) Calculate the number of pixels N of the radiation source on the image plane of the photoelectric imaging system. The calculation formula is as follows: N = {(X RT - X LT ) + (X RD - X LD )} × (Y LD - Y LT ) / 2 (Formula 3); (5.4) Calculate the area measurement value S of the optoelectronic imaging system for the area enclosed by the edge connection line of the radiation source array target selected in step (5.1) * (m 2 ):

7. The method for evaluating area measurement error of a multi-band optoelectronic imaging system according to claim 2, characterized in that: The specific steps of step (6) are as follows: (6.1) Calculate the area S0 (m 2 ): S0=((m-1)×ΔL) 2 =(γ×L FOV ×(m-1) / (n-1)) 2 (Formula 5); (6.2) Calculate the projection area S (m 2 ): S = S0 × cosd (θ + β) (Formula 6) Where cosd is the cosine function.

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