An optical method for detecting and reconstructing hidden targets based on specular reflection light

Abstract

This invention provides an optical hidden target detection and contour restoration method based on specular reflection light. It constructs a spatial relationship model between the observer, obstructions, the target, and the water surface, providing a foundation for target localization and contour restoration. An optical path map of the target is constructed using water surface reflection light, and a feature comparison algorithm is used to analyze the optical path map to obtain the target's location, increasing the probability and accuracy of detection. Based on the target's location and optical path map, the target's coordinates are calculated, and the target's contour is restored from the coordinates. This invention relies solely on optical fiber propagation and reflection without requiring additional equipment and resources, reducing costs and offering strong adaptability.

Description

Technical Field

[0001] This invention relates to the field of optical hidden target detection, and more particularly to a method for optical hidden target detection and contour recovery based on specular reflection light. Background Technology

[0002] In field reconnaissance and detection operations, targets are often obscured by terrain, vegetation, or other objects. For example, in urban environments, buildings, transportation facilities, parks, and green spaces can all block the detector's direct line of sight to the target. Effectively detecting and analyzing obscured targets is not only a technical challenge but also crucial to the success of reconnaissance and detection operations.

[0003] Traditional detection methods, such as radar, sonar, and infrared, while possessing certain detection capabilities, suffer significant degradation in specific environments, such as urban areas or complex terrain. Furthermore, these traditional methods often require substantial equipment and incur high costs, making them unsuitable for large-scale or low-cost applications.

[0004] In recent years, methods for detection and reconnaissance using optical principles have received increasing attention. By utilizing the properties of light such as reflection, refraction, and scattering, the position, shape, and other attributes of a target can be obtained from the information in the light. However, optical detection methods still face many challenges when dealing with occlusion problems. For example, how to use the information from light reflection and refraction to reconstruct the outline of an occluded target, and how to use the information from light scattering and absorption to determine the material and state of the target, etc. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides an optical hidden target detection and contour restoration method based on specular reflection light. By utilizing the viewing angle difference between water surface reflected light and direct light, the contour of the occluded target object can be quickly and accurately located and restored, with higher precision and lower cost.

[0006] To achieve the above objectives, the present invention provides an optical hidden target detection and contour recovery method based on specular reflection light, comprising the following steps:

[0007] S1: Construct a spatial relationship model between the observer, obstructions, target, and water surface;

[0008] S2: Construct the optical path map of the target under test by reflecting light from the water surface, and use a feature comparison algorithm to analyze the optical path map to obtain the location of the target under test;

[0009] S3: Based on the location and optical path diagram of the target under test, calculate the coordinates of the target under test, and reconstruct the outline of the target under test according to the coordinates.

[0010] Preferably, in the spatial relationship model, the obstruction is located between the observer and the target, and the water surface is set in the middle area between the target and the observer. The observer forms an observer projection through the reflection of the water surface.

[0011] Preferably, when constructing the optical path diagram, the projection of the occluder in the observer and the observer's projection view is constructed by combining light reflection, and the projection of the target under test in the observer's projection view is constructed.

[0012] Preferably, the feature matching algorithm is the HOG operator or the PROB operator. The matching relationship between the occluder and the observer's projected view is obtained through the feature matching algorithm, and the position of the target to be tested is obtained based on the matching relationship.

[0013] Preferably, after obtaining the location of most targets to be measured, auxiliary analysis lines are drawn based on the formed optical path diagram to form a contour analysis diagram; the coordinates of the targets to be measured are calculated through the contour analysis lines, and the contour of the targets to be measured is recovered based on the coordinates.

[0014] Preferably, the steps for calculating the coordinates of the target to be measured include:

[0015] S4.1: Based on the contour analysis diagram, obtain the optical axis position Q1 of the observer, the visual point E1, the optical axis position Q2 of the observer's projection, and the visual point E2.

[0016] S4.2: Calculate the position of the outermost point of the target to be measured;

[0017] Let the center point of the obstruction be K, the center point of the target be T, and the optical axis distance between the observer and the observer's projection be x; let the projection point of the center point of the obstruction on the observer's projection be K2, and the projection point of the center point of the target be T2. Based on the optical path diagram, we can obtain:

[0018] O1K / O2E2=K2O2 / (K2O2+x),

[0019] Where O1K is the distance between the occluder and the observer, the focal length O2E2 is f, and K2O2 is the distance between the occluder at the observer's projection point and the position of the observer's projection optical axis. The distance K2O2 is known.

[0020] The distance O1K between the obstruction and the observer is:

[0021] O1K = K202 * f / (K202 + x);

[0022] The distance O1T between the target and the observer is:

[0023] O1T = T2O2 * f(T2O2 + x);

[0024] The height AT from the outermost point to the center point of the target to be measured is:

[0025] AT = A2T2*f / (O1T-T202);

[0026] Where A2T2 is the distance between the outermost point and the center point of the target under test on the observer's projection, and T202 is the distance between the projection point of the target under test on the observer's projection and the optical axis position of the observer's projection;

[0027] The projection distance A1O1 of the outermost point of the target under test on the observer's view is obtained based on the height AT from the outermost point to the center point, thus determining the position of the outermost point of the target. The formula for calculating the projection distance A1O1 is as follows:

[0028] A1O1=AT*f / (O1T-f)=A2T2*f / (O1T-T202)*f / (O1T-f).

[0029] Preferably, the calculation step of the target position further includes: S4.3: using the method of step S4.2 to obtain the position of all contour points of the target.

[0030] This invention provides an optical hidden target detection and contour restoration method based on specular reflection light. Its advantages lie in its ability to locate the target by means of reflected light from the water surface without direct observation of the target, through a constructed spatial relationship model, greatly increasing the possibility and accuracy of reconnaissance. By calculating and analyzing the reflection path using feature comparison algorithms, the contour of the target is restored, effectively improving the accuracy of target identification and tracking. This invention relies solely on the propagation and reflection of optical fibers for contour restoration, requiring no additional equipment or resources, resulting in low cost and strong adaptability. Attached Figure Description

[0031] Figure 1 A schematic diagram of the spatial model provided for this invention;

[0032] Figure 2 The optical path diagram of the target under test provided by this invention;

[0033] Figure 3 This is a schematic diagram of the auxiliary analysis line constructed for the optical path diagram of the target under test provided by the present invention. Detailed Implementation

[0034] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0035] This invention provides an optical hidden target detection and contour recovery method based on specular reflection light, the specific steps of which include:

[0036] S1: Construct a spatial relationship model between the observer, obstructions, target, and water surface;

[0037] S2: Construct the optical path map of the target under test by reflecting light from the water surface, and use a feature comparison algorithm to analyze the optical path map to obtain the location of the target under test;

[0038] S3: Based on the location and optical path diagram of the target under test, calculate the coordinates of the target under test, and reconstruct the outline of the target under test according to the coordinates.

[0039] Specifically, this invention constructs a spatial relationship model between the observer, the obstruction, and the target, and uses water surface reflection to reflect the outline light of the target into the observer's field of vision, providing a basis for the localization and outline recovery of the target. Based on the constructed spatial relationship model, a light path map is constructed in combination with water surface features, and the position of the target is calculated through a feature comparison algorithm, greatly increasing the possibility and accuracy of detection. By calculating and analyzing the reflection path, the outline of the target can be quickly recovered. The process relies only on light propagation and reflection, without the need for additional equipment or resources, and is low in cost and highly adaptable.

[0040] The spatial relationship model constructed in this invention is as follows: Figure 1 As shown in the spatial relationship model, the obstruction is located between the target and the observer, completely blocking the observer's straight-line view. The water surface is positioned in the middle area between the target and the observer. Therefore, by utilizing the reflection from the water surface, light from the target can be reflected into the observer's field of view, making it possible to locate and reconstruct the outline of the target. Figure 1 In this model, the outermost point of the target to be measured is designated as A (the highest point), and the lowest point as B. The outermost point of the obstruction is designated as C, and the lowest point as D. As can be seen in the ray diagram of the spatial model, the observer can directly observe the projections of the target and the obstruction (the outermost point A of the target and the outermost point C of the obstruction) through water surface reflection, thus enabling their detection. Utilizing these reflection features (features A, B, and C) provides a foundation for the rapid and stable detection of the target after obstruction.

[0041] In this embodiment, after obtaining the spatial relationship model, an optical path diagram of the target under test is constructed in the current state. In the optical path diagram, the observer's projection is formed by the reflection on the water surface. When constructing the optical path diagram, the projections of the occluder in the observer's and observer's projection views are constructed by combining light reflection, and the projection of the target under test in the observer's projection view is also constructed. Specifically, the occluder forms projection C1D1 in the observer's view and projection C2D2 in the observer's projection view, while the target under test forms projection A2B2 in the observer's view. The obtained projection features are used to obtain the matching relationship between the projection points C1 and C2, and D1 and D2 of the occluder using a feature comparison algorithm; while the projection area A2B2 is an unmatched area, which is the area where the target under test is located, thus the position of the target under test can be located. The method of determining the position of the target under test through matching relationships does not require the use of other measuring equipment, has low implementation cost, and also improves the positioning speed and detection efficiency of the target under test. To ensure accurate positioning, the reflection characteristics of the water surface are precisely modeled and calculated to estimate the reflection angle deviation. In an ideal mirror-like condition, the reflection angle deviation is 0 degrees. Under natural conditions, the water surface undulates due to water flow, wind, etc. The degree of water surface undulation is determined by measuring the brightness changes in the water surface area. The greater the change in brightness intensity, the greater the water surface undulation, and the greater the reflection angle deviation. In this embodiment, the feature comparison algorithms used include, but are not limited to, the HOG operator and the PROB operator.

[0042] In this embodiment, after obtaining the locations of most targets to be measured, auxiliary analysis lines are drawn based on the formed optical path diagram to form a contour analysis diagram; the position of the target to be measured is calculated through the contour analysis lines, and the contour of the target to be measured is recovered based on the coordinates. Specifically, auxiliary analysis lines are drawn in the obtained optical path diagram to form a contour analysis diagram, such as... Figure 3 As shown, two parallel auxiliary lines are drawn at the observer's and the viewpoint of their projection, respectively. The position of the target is calculated using these auxiliary lines. The calculation steps include:

[0043] S4.1: Based on the contour analysis diagram, obtain the optical axis position Q1 of the observer, the visual point E1, the optical axis position Q2 of the observer's projection, and the visual point E2.

[0044] S4.2: Calculate the position of the outermost point of the target to be measured;

[0045] Assume the center points of the occluder and the target are K and T, respectively, both located on the optical axis. Assume the distance between the observer and the optical axis of the observer's projection is x (O1O2). To recover the target's contour, it is necessary to estimate the distances O1T and AT / BT from the observer's optical path position to the target. The projection points of the center points (K and T) of the occluder and the target on the observer's projection are K2 and T2. Since optical axes O1 and O2 are parallel, triangle K2O2E2 is similar to triangle K2O1K, therefore:

[0046] O1K / O2E2=K2O2 / (K2O2+x);

[0047] Where the focal length O2E2 is f, K2O2 is the distance between the obstruction and the observer's projection point, and the distance K2O2 is known; therefore, the distance O1K between the obstruction and the observer can be obtained as:

[0048] O1K = K202 * f / (K202 + x);

[0049] Similarly, the distance O1T between the target and the observer is:

[0050] O1T = T2O2 * f(T2O2 + x);

[0051] The height AT from the outermost point to the center point of the target to be measured is:

[0052] AT / A2T2=O2E2 / (O1T-T202);

[0053] Based on the above analysis, we have:

[0054] AT=A2T2*O2E2 / (O1T-T202)=A2T2*f / (O1T-T202);

[0055] Where A2T2 is the distance between the outermost point and the center point of the target on the observer's projection, and T202 is the distance between the projection point of the target on the observer's projection and the optical axis position of the observer's projection.

[0056] The projection distance A1O1 of the outermost point of the target on the observer's view can be obtained from the height AT from the outermost point to the center point, thus determining the position of the outermost point of the target. The formula for calculating the projection distance A1O1 is as follows:

[0057] A1O1 / AT=O1E1 / E1T=f / (O1T-f);

[0058] Where O1E1 is the distance between the observer's optical axis position and the visual point, O1T is the distance between the observer's optical axis position and the center point of the target to be measured, and E1T is the distance between the observer's visual point and the center point of the target to be measured.

[0059] Simplifying the above equation, we get:

[0060] A101=AT*f / (O1T-f)=A2T2*f / (O1T-T202)*f / (01T-f);

[0061] The projection point A1 of the outermost point A of the target under test in the observer's view can be determined by the above method.

[0062] S4.3: Obtain the positions of all contour points of the target under test using the method in step S4.2. For example, B1, B2, etc. After calculating the positions of all contour points, the contour of the target under test can be recovered, obtaining the complete shape of the target.

[0063] Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

Claims

1. A method for optical hidden target detection and contour restoration based on specular reflection light, characterized in that, Includes the following steps: S1: Construct a spatial relationship model between the observer, obstructions, target, and water surface; S2: Construct the optical path map of the target under test by reflecting light from the water surface, and use a feature comparison algorithm to analyze the optical path map to obtain the location of the target under test; S3: Based on the location and optical path diagram of the target under test, calculate the coordinates of the target under test, and reconstruct the outline of the target under test according to the coordinates; The steps for calculating the coordinates of the target to be measured include: S4.1: Based on the contour analysis diagram, obtain the optical axis position Q1 of the observer, the visual point E1, the optical axis position Q2 of the observer's projection, and the visual point E2. S4.2: Calculate the position of the outermost point of the target to be measured; Let the center point of the obstruction be K, the center point of the target be T, and the optical axis distance between the observer and the observer's projection be x; let the projection point of the center point of the obstruction on the observer's projection be K2, and the projection point of the center point of the target be T2. Based on the optical path diagram, we can obtain: O1K / O2E2=K2O2 / (K2O2+x), Where O1K is the distance between the occluder and the observer, the focal length O2E2 is f, and K2O2 is the distance between the occluder at the observer's projection point and the position of the observer's projection optical axis. The distance K2O2 is known. The distance O1K between the obstruction and the observer is: O1K = K202 * f / (K202 + x); The distance O1T between the target and the observer is: O1T = T2O2 * f(T2O2 + x); The height AT from the outermost point to the center point of the target to be measured is: AT = A2T2*f / (O1T-T202); Where A2T2 is the distance between the outermost point and the center point of the target under test on the observer's projection, and T202 is the distance between the projection point of the target under test on the observer's projection and the optical axis position of the observer's projection. The projection distance A1O1 of the outermost point of the target under test on the observer's view is obtained based on the height AT from the outermost point to the center point, thus determining the position of the outermost point of the target under test. The formula for calculating the projection distance A1O1 is as follows: A1O1= AT*f / (O1T-f) =A2T2*f / (O1T-T202)*f / (O1T-f).

2. The optical concealed target detection and contour restoration method based on specular reflection light according to claim 1, characterized in that, In the spatial relationship model, the obstruction is located between the observer and the target, and the water surface is set in the middle area between the target and the observer. The observer forms an observer projection through the reflection of the water surface.

3. The optical concealment target detection and contour restoration method based on specular reflection light according to claim 1, characterized in that, When constructing the light path diagram, the projection of the occluder in the observer and the observer's projection view is constructed by combining light reflection, and the projection of the target under test in the observer's projection view is constructed.

4. The optical concealment target detection and contour restoration method based on specular reflection light according to claim 1, characterized in that, The feature matching algorithm is either the HOG operator or the PROB operator. The matching relationship between the occluder and the observer's projected view is obtained through the feature matching algorithm, and the position of the target to be tested is obtained based on the matching relationship.

5. The optical concealed target detection and contour restoration method based on specular reflection light according to claim 1, characterized in that, After obtaining the location of most of the targets to be measured, auxiliary analysis lines are drawn based on the formed optical path diagram to form a contour analysis diagram; the coordinates of the targets to be measured are calculated through the contour analysis lines, and the contour of the targets to be measured is recovered based on the coordinates.

6. The optical concealment target detection and contour restoration method based on specular reflection light according to claim 1, characterized in that, The calculation steps for the position of the target to be measured also include: S4.3: using the method in step S4.2 to obtain the positions of all contour points of the target to be measured.

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