A transient passive array 3D imaging method for time-varying terrain features

Abstract

The present invention relates to a method for instantaneous passive area array 3D imaging of time-varying terrain features, comprising: imaging with a full-time polarization 3D imaging device; obtaining polarization information images of the time-varying terrain features; determining the characteristics of the terrain features' polarization information; classifying complex terrain features at the pixel level using polarization degree; establishing a polarization 3D imaging model; calculating microfacet normals using polarization information; and obtaining the 3D topography of the time-varying terrain features. This method can perform instantaneous area array 3D monitoring of terrain features in areas corresponding to geological hazards such as collapses, landslides, debris flows, and barrier lakes, or for production safety targets such as tailings pond monitoring. The method transmits the integrated image and height information to emergency disaster relief departments, providing data support for disaster assessment, mitigation, and rescue efforts.

Description

Technical Field

[0001] The invention relates to an instantaneous passive area array three-dimensional imaging method for time-varying ground objects, and belongs to the technical field of novel monocular three-dimensional imaging. Background Art

[0002] Since geological disasters occur at uncertain times and locations, continue to occur over a period of time, and have complex terrain in the disaster area, the payload used for disaster observation needs to have a large observation range to meet the needs of real-time monitoring of sudden geological disasters at a certain location; it also needs to have all-day imaging capabilities to meet the needs of monitoring geological disasters that occur randomly during the day and at night; it also needs to have high-precision three-dimensional imaging capabilities. During post-disaster emergency response and rescue, the two-dimensional images of the disaster-stricken area are difficult to reflect the complex terrain characteristics of the disaster area. Therefore, the observation payload needs to provide high-precision three-dimensional information of the ground area to meet the monitoring needs of disaster areas with complex terrain; it also needs to have instantaneous array three-dimensional imaging capabilities to meet the monitoring needs of geological disasters that change continuously over a period of time.

[0003] Currently, the technologies available for acquiring three-dimensional information about ground objects primarily include stereo mapping, laser three-dimensional imaging, and IN-SAR. Stereo mapping utilizes a dual- or triple-line array push-broom mode. Due to baseline limitations, each line array camera must scan the same ground object to resolve three-dimensional information. This results in limited timeliness and high image matching requirements. If a ground object is obscured from a certain perspective, three-dimensional reconstruction is impossible. Laser three-dimensional imaging utilizes a multi-point laser push-broom method, which struggles to achieve wide coverage of ground objects. It requires active lasers, consumes a lot of energy, and is prohibitively expensive to implement. IN-SAR technology places high demands on satellite control accuracy and observation errors due to atmospheric delay. Relevant literature indicates that an orbit error of 1.0 cm will result in an elevation error of 5.7 m. Existing technologies cannot meet the requirements for instantaneous array three-dimensional imaging of time-varying ground objects. Summary of the Invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of existing technologies that can be used to obtain three-dimensional information of ground objects, and based on the needs of monitoring geological disasters that have caused serious losses to my country, a method for instantaneous passive area array three-dimensional imaging of time-varying ground objects is proposed to achieve large-scale, all-day, high-precision instantaneous area array three-dimensional imaging of ground objects in geological disaster areas.

[0005] The solution of the present invention is:

[0006] A method for instantaneous passive area array three-dimensional imaging of time-varying terrain objects comprises the following steps:

[0007] 1) imaging a target area using a polarization three-dimensional imaging device to obtain a ground object polarization information image; the ground object polarization information image is composed of a plurality of unit blocks;

[0008] 2) Using the ground object polarization information image obtained in step 1), extract the light intensity information to obtain the ground object polarization information corresponding to each unit block; the ground object polarization information includes: polarization degree p and polarization angle

[0009] 3) Dividing the ground object polarization information image into multiple regions based on the polarization degree p obtained in step 2) and the polarization degree value ranges of different ground object types, wherein the unit blocks in the same region belong to the same ground object type; obtaining the refractive index information n corresponding to each unit block based on the refractive index n corresponding to the ground object type;

[0010] 4) Using the ground object polarization information obtained in step 2) and the refractive index information n obtained in step 3), obtain the ground object gradient field N corresponding to each unit block x 、N y 、N z ;

[0011] 5) Using step 4), the ground object gradient field corresponding to each unit block is obtained, and the three-dimensional surface restoration function of the ground object is determined, thereby obtaining the three-dimensional morphology of the time-varying ground object.

[0012] Preferably, the polarization three-dimensional imaging device uses polarized light reflected or radiated by the ground object to perform polarization three-dimensional imaging of the ground object; the polarization three-dimensional imaging device is a planar array imaging remote sensor, and the imaging area is greater than one hundred square kilometers.

[0013] Preferably, the land feature types include: grassland, trees, gravel and soil, water bodies, and shrubs.

[0014] Preferably, the method of obtaining the ground object polarization information corresponding to each unit block in step 2) is specifically as follows:

[0015] 21) using the ground object polarization information image obtained in step 1), obtaining light intensity information in multiple different linear polarization directions in each unit block;

[0016] 22) Determine the Stokes vector S based on the light intensity information obtained in step 21);

[0017] 23) According to the Stokes vector S determined in step 22), the polarization degree p and polarization angle corresponding to each unit block are obtained. As ground object polarization information.

[0018] Preferably, each unit block in step 1) consists of 2 by 2 pixels; each unit block can provide light intensity information in 3 or 4 linear polarization directions.

[0019] Preferably, in step 1), each unit block can provide light intensity information with linear polarization directions of 0°, 45°, 90°, and 135° (I 0° , I 45°, I 90° , I 135° ).

[0020] Preferably, the method for determining the Stokes vector S in step 22) is specifically as follows:

[0021]

[0022] Among them, I, Q and U are the three parameters of the Stokes vector S, I represents the total intensity of the light wave, Q represents the difference between the intensities of the linearly polarized light at 0° and 90°, and U represents the difference between the intensities of the linearly polarized light at 45° and 135°.

[0023] Preferably, in step 1), each unit block can provide light intensity information with linear polarization directions of 0°, 45° and 90° (I 0° , I 45° , I 90° ).

[0024] Preferably, the method for determining the Stokes vector S in step 22) is specifically:

[0025]

[0026] Among them, I, Q and U are the three parameters of the Stokes vector S, I represents the total intensity of the light wave, Q represents the difference between the intensities of the linearly polarized light at 0° and 90°, and U represents the difference between the intensities of the linearly polarized light at 45° and 135°.

[0027] Preferably, in step 1), each unit block can provide light intensity information with linear polarization directions of 0°, 60° and 120° (I 0° , I 60° , I 120° ).

[0028] Preferably, the method for determining the Stokes vector S in step 22) is specifically:

[0029]

[0030] Among them, I, Q and U are three parameters of the Stokes vector S, I represents the total intensity of the light wave; Q represents the linearly polarized light component in the horizontal direction; and U represents the linearly polarized light component in the 45° direction.

[0031] Preferably, the method for determining the polarization degree p in step 23) is specifically as follows:

[0032]

[0033] Preferably, in step 23) the polarization angle The method for determining is as follows:

[0034]

[0035] Preferably, step 4) obtains the ground object gradient field N corresponding to each unit block x 、N y 、N z The method is as follows:

[0036] 41) determining the normal zenith angle θ based on the polarization degree p obtained in step 2) and the refractive index information n obtained in step 3);

[0037] 42) According to the normal zenith angle θ determined in step 41) and the polarization angle obtained in step 2) Determine the ground object gradient field N corresponding to each unit block x 、N y 、N z .

[0038] Preferably, the method for determining the normal zenith angle θ in step 41) is specifically as follows:

[0039]

[0040] Preferably, step 42) determines the ground object gradient field N corresponding to each unit block x 、N y 、N z The method is as follows:

[0041]

[0042] The right-handed rectangular coordinate system is established with the center of the unit block as the origin. The positive direction of the z-axis is perpendicular to the surface of the unit block and upward. The x-axis and the y-axis are parallel to the length and width directions of the pixel in the ground object polarization information image, respectively. x Represents the normal vector The component in the x-axis direction, N y Represents the normal vector The component in the y-axis direction, N z Represents the normal vector Component in the z-axis direction.

[0043] The advantages of the present invention compared with the prior art are:

[0044] 1) The present invention utilizes the polarization information of ground objects to realize instantaneous array three-dimensional monitoring of ground objects in geological disaster areas. By utilizing the correspondence between the normal direction of micro-facets on the ground object surface and the polarization characteristics of reflected or radiated light, the polarization parameters of the light reflected or radiated by the ground object are solved to obtain the normal vector information of micro-facets on the ground object surface, thereby realizing the reconstruction of the three-dimensional morphology of the ground object.

[0045] 2) This invention eliminates the need for baseline restrictions, multiple imaging, image matching, or active light sources. It offers the advantages of large-scale monitoring, 24 / 7 operation, high-precision 3D imaging, and instantaneous array imaging. It can achieve large-scale, 24 / 7, high-precision, instantaneous array 3D imaging of objects in time-varying geological disaster zones. Stereo mapping technology is limited by baselines and requires multiple imaging from different perspectives. The matching requirements for these different perspectives are high, making it difficult to apply to 3D imaging of time-varying objects. Laser 3D imaging requires an active light source and multiple point imaging, making large-scale coverage difficult. IN-SAR technology is also limited by baselines and requires multiple imaging steps.

[0046] 3) The present invention can be applied to the three-dimensional monitoring of time-varying landforms, the three-dimensional imaging of other continuously changing landforms, the three-dimensional imaging of satellite objects and celestial bodies in relative motion in space, the three-dimensional monitoring of tunnel wall deformation, the three-dimensional reconstruction of translucent objects, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a flow chart of a method for instantaneous passive area array three-dimensional imaging of time-varying terrain objects according to the present invention;

[0048] Figure 2 It is a schematic diagram of the subdivision of the components of the present invention;

[0049] Figure 3 A schematic diagram of the mechanism for establishing the polarization three-dimensional imaging model of the present invention;

[0050] Figure 4 This is a schematic diagram of the surface normal polar coordinates of the present invention;

[0051] Figure 5 Schematic diagram of light wave refraction phenomenon;

[0052] Figure 6(a) is a schematic diagram of the polarization ellipse;

[0053] FIG6( b ) is a schematic diagram showing the geometric relationship between the surface normal of an object and the polarization ellipse. DETAILED DESCRIPTION

[0054] The polarization three-dimensional imaging device has instantaneous imaging capabilities and can simultaneously obtain images in three or four linear polarization directions. It can meet the special needs of three-dimensional imaging of ground objects, space targets, and aerial targets that change rapidly with time. It can also perform three-dimensional imaging of ground objects, space targets, and aerial targets that change slowly or not change with time.

[0055] The polarization three-dimensional imaging device has the capability of passive imaging, and uses the polarized light reflected or radiated by the ground objects to perform polarization three-dimensional imaging of the ground objects.

[0056] The polarization 3D imaging device possesses area array imaging capabilities, enabling instantaneous acquisition of polarization-based 3D images of large, time-varying features. It is particularly well-suited for 3D monitoring of geological disaster zones spanning tens or hundreds of kilometers. The polarization 3D imaging device is an area array imaging remote sensor capable of imaging areas exceeding 100 square kilometers.

[0057] The flow chart of the instantaneous passive array three-dimensional imaging method of time-varying terrain in the present invention is as follows: Figure 1 As shown, the steps include:

[0058] 1) Using an all-day polarization 3D imaging device to image a target area (e.g., a geological disaster area) to obtain a time-varying ground feature polarization information image; the time-varying ground feature polarization information image is composed of multiple unit blocks, each unit block consisting of 2 by 2 pixels; each unit block can provide light intensity information in three or four linear polarization directions; that is, a time-varying ground feature polarization information image containing three or four linear polarization directions is simultaneously obtained, and the linear polarization directions can be 0°, 45°, 90°, 135°, or 0°, 45°, 90°, or 0°, 60°, 120°.

[0059] Select a certain linear polarization direction as the reference, denoted as 0°. Rotate the linear polarizer 45° clockwise relative to the 0° reference direction to obtain a linear polarization direction of 45°. Similarly, rotate the linear polarizer 90° and 135° clockwise relative to the 0° reference direction to obtain linear polarization directions of 90° and 135°. Counterclockwise rotation is also possible.

[0060] In view of the need for geological disaster monitoring, monitoring is required both during the day and at night. The polarization three-dimensional imaging device used in the present invention has the ability to monitor both during the day and at night.

[0061] 2) Using the ground object polarization information image obtained in step 1), extract the light intensity information and obtain the ground object polarization information characteristics represented by the Stokes vector S corresponding to each unit block; the ground object polarization information characteristics include: polarization degree p and polarization angle

[0062] Step 2) The method for obtaining the polarization information characteristics of the ground object corresponding to each unit block is specifically as follows:

[0063] 21) using the ground object polarization information image obtained in step 1), obtaining light intensity information in multiple different linear polarization directions in each unit block;

[0064] 22) Determine the Stokes vector S based on the light intensity information obtained in step 21);

[0065] When the unit block provides light intensity information in the four linear polarization directions of 0°, 45°, 90°, and 135°, and the linear polarization light is completely polarized, the Stokes vector S is expressed as follows:

[0066]

[0067] Among them, I, Q and U are the three parameters of the Stokes vector S, I represents the total intensity of the light wave, Q represents the difference between the intensity of the linearly polarized light at 0° and 90°, and U represents the difference between the intensity of the linearly polarized light at 45° and 135°. 0° , I 90° , I 45° and I 135° I represents the intensity of light waves passing through ideal linear polarizers at horizontal, vertical, 45° and 135°, respectively. 0° +I 90° =I 45° +I 135° .

[0068] When the unit block provides light intensity information in the three linear polarization directions of 0°, 45°, and 90°, and the linear polarization light is completely polarized light, the Stokes vector S is expressed as follows:

[0069]

[0070] Among them, I, Q and U are the three parameters of the Stokes vector S, I represents the total intensity of the light wave, Q represents the difference between the intensity of the linearly polarized light at 0° and 90°, and U represents the difference between the intensity of the linearly polarized light at 45° and 135°. 0° , I 90° and I 45° Represents the intensity of light waves passing through horizontal, vertical and 45° ideal linear polarizers. U represents the difference in intensity between 45° and 135° linear polarization. So U can be expressed as

[0071] When the unit block provides light intensity information in the three linear polarization directions of 0°, 60°, and 120°, and the linear polarization light is completely polarized light, the Stokes vector S is expressed as follows:

[0072]

[0073] Among them, I, Q and U are the three parameters of the Stokes vector S, I represents the total intensity of the light wave; Q represents the linear polarization component in the horizontal direction; U represents the linear polarization component in the 45° direction; I 0° , I 60° and I 120° Represents the intensity of light waves passing through ideal linear polarizers at horizontal, 60° and 120° respectively.

[0074] 23) According to the Stokes vector S determined in step 22), the polarization degree p and polarization angle corresponding to each unit block are obtained. As the polarization information characteristic of ground objects.

[0075] Step 23) The method for determining the polarization degree p is specifically as follows:

[0076]

[0077] Step 23) the polarization angle The method for determining is as follows:

[0078]

[0079] 3) Based on the polarization degree p obtained in step 2) and the polarization degree value ranges of different feature types, the feature polarization information image is divided into multiple regions, where the unit blocks in the same region belong to the same feature type; the refractive index n corresponding to each unit block is obtained using the refractive index n corresponding to the feature type; and polarization 3D reconstruction is performed on each region to improve the 3D reconstruction accuracy. Feature types include: grass, trees, gravel and soil, water, and shrubs;

[0080] 4) Using the ground object polarization information characteristics obtained in step 2) and the refractive index information n obtained in step 3), a polarization 3D imaging model is established to obtain the ground object gradient field N corresponding to each unit block. x 、N y 、N z ;

[0081] Step 4) Obtain the ground object gradient field N corresponding to each unit block x 、N y 、N z The method is as follows:

[0082] 41) Determine the normal zenith angle θ based on the polarization degree p obtained in step 2) and the refractive index information n obtained in step 3); specifically:

[0083]

[0084] Among them, n is the refractive index of different types of landforms. The refractive index of electrolytes on the surface of most materials is generally 1.4-1.6.

[0085] 42) According to the normal zenith angle θ determined in step 41) and the polarization angle obtained in step 2) Determine the ground object gradient field N corresponding to each unit block x 、N y 、N z ; Specifically:

[0086]

[0087] The right-handed rectangular coordinate system is established with the center of the unit block as the origin. The positive direction of the z-axis is perpendicular to the surface of the unit block and upward. The x-axis and the y-axis are parallel to the length and width directions of the pixel in the time-varying ground feature polarization information image, respectively. x Represents the normal vector The component in the x-axis direction, N y Represents the normal vector Component in the y-axis direction, N z Represents the normal vector The component in the z-axis direction, such as Figure 4 As shown, the normal vector is the direction vector, after normalization N z The value is 1, no unit. θ∈[0°,90°],

[0088] 5) Using step 4), the ground object gradient field corresponding to each unit block is obtained, and the three-dimensional surface restoration function of the ground object is determined, thereby obtaining the three-dimensional morphology of the time-varying ground object.

[0089] Step 1) can adopt the methods of multi-aperture polarization imaging with the same field of view, polarization imaging with multiple linear polarization directions rotated by a single aperture, and split-focus plane polarization imaging, and can simultaneously obtain imaging of a planar array all-day polarization three-dimensional imaging device that can obtain information on three or four linear polarization directions; the all-day polarization three-dimensional imaging device imaging uses the polarization characteristics of light reflected or radiated by the ground object to perform three-dimensional reconstruction, and is a passive three-dimensional imaging method; the all-day polarization three-dimensional imaging device imaging adopts visible and infrared working modes, which can achieve all-day monitoring; compared with other three-dimensional imaging methods, the all-day polarization three-dimensional imaging device imaging has the advantages of small size and light weight, can be located on a space-based platform or an air-based platform, and can use the platform's side swing maneuverability to achieve long-term, large-scale monitoring of time-varying ground objects.

[0090] The time-varying ground object polarization information image obtained in step 1) contains polarization information of ground objects in corresponding areas, such as geological disasters such as collapses / landslides / mudslides, barrier lakes, or production safety targets such as tailings pond monitoring, which change rapidly with time. The ground object polarization information is obtained by imaging with a full-time polarization three-dimensional imaging device.

[0091] The present invention adopts a monocular instantaneous array polarization imaging method, which is not restricted by baselines and can calculate the three-dimensional information of ground objects using a single single-frame image. It is more suitable for three-dimensional monitoring of time-varying ground objects; the ground objects can be reconstructed in three dimensions as long as they are visible; the passive imaging energy requirement is low; compared with other three-dimensional imaging methods, polarization three-dimensional imaging has low complexity in solving the three-dimensional information of ground objects, does not require image matching, and has high elevation inversion accuracy (1-2 times the spatial resolution).

[0092] The present invention has the characteristics of monocular, area array, passive, instantaneous, all-day, and large-scale three-dimensional imaging. It can meet the needs of geological disasters with uncertain occurrence time, uncertain occurrence location, continuous occurrence within a period of time, and complex terrain in the occurrence area for large-scale monitoring, all-day operation, high-precision three-dimensional imaging, and instantaneous area array imaging. It can play an important role in disaster risk assessment and early warning, disaster assessment, and formulation of emergency disaster rescue measures in emergency disaster reduction.

[0093] This invention can be applied to 3D monitoring of time-varying features, 3D imaging of other continuously changing features, and 3D imaging of other satellites in relative motion while on a satellite. It can also be used for 3D monitoring of tunnel wall deformation and 3D reconstruction of translucent objects. Satellites often have multiple key components made of varying materials. The feature classification method described in this invention can be used to categorize these key components and improve the accuracy of polarization-based 3D imaging of the entire satellite.

[0094] The present invention will be further described below in conjunction with the embodiments.

[0095] The instantaneous passive array three-dimensional imaging method of a time-varying terrain object of the present invention is composed as follows: Figure 1 As shown, the system includes imaging with a polarization 3D imaging device, obtaining polarization information images of time-varying features, solving the polarization information characteristics of the features, establishing a polarization 3D imaging model, calculating microfacet normals using the polarization information, and obtaining the time-varying 3D topography of the features. This system can perform instantaneous 3D area array monitoring of features in areas corresponding to geological hazards such as collapses, landslides, debris flows, and barrier lakes, as well as safety production targets such as tailings pond monitoring. This integrated image and height information is then transmitted to emergency disaster relief departments, providing data support for disaster assessment, mitigation, and rescue efforts.

[0096] A schematic diagram of the components of a method for instantaneous passive array 3D imaging of time-varying terrain according to the present invention is shown in FIG. Figure 2As shown, the polarization 3D imaging device consists of a high-polarization-maintaining optical lens, components such as multi-aperture polarization in the same field of view, single-aperture rotating multi-polarization direction polarization, and focal plane polarization, as well as a polarization 3D reconstruction module. It can simultaneously obtain information on three or four linear polarization directions. Operating in visible and infrared modes, it enables all-day imaging. Using an array of detectors, it can also image ground objects in an array array. Compared to other 3D imaging methods, it is compact and lightweight. Time-varying ground object polarization information images are acquired, including A1-, A2-, and A3-degree linear polarization direction images. A1, A2, and A3 are the angles of the three linear polarization directions relative to a reference direction from which the Stokes vector can be calculated. These can be three or four linear polarization directions, and can be 0°, 45°, 90°, 135°, or 0°, 60°, and 120°. The ground object polarization characteristics obtained include the Stokes vector, degree of polarization, polarization angle, and other polarization information parameters that can be used to calculate the normal zenith angle and normal azimuth. Using polarization to classify complex objects involves determining the correspondence between object types and polarization ranges in geological disaster areas through on-the-ground measurements and other methods. This is then combined with pixel-level polarization information derived from solving for object polarization characteristics to perform pixel-level classification. A polarization-based 3D imaging model is established, including a normal zenith angle model and a normal azimuth angle model. Due to the specificity of 3D surface analysis, it is not possible to directly reconstruct the 3D surface through integration based on the calculation of microfacet normals using polarization information. Instead, a 3D surface restoration function based on the Frankot-Chellappa algorithm is used to obtain the time-varying 3D topography of the object.

[0097] The detailed model of the normal zenith angle is:

[0098] For non-uniform medium objects, the diffuse reflected light on its surface is mainly composed of the refracted light after the incident light enters the target and undergoes multiple refractions and then refracts back into the air. Therefore, the polarization degree of the diffuse reflected light can be expressed as the polarization degree of the refracted light. Figure 5 As shown, the incident angle of the incident light is θ i The refraction angle θ is the zenith angle of the normal. In polarization 3D imaging, light waves are mainly incident from air to the target surface, that is, light is incident from an optically rarefaction medium to an optically dense medium.

[0099] The light wave is decomposed into the s component vibrating perpendicular to the incident plane and the p component vibrating parallel to the incident plane. The refractive index T of the S component of the light wave is s and the refractive index T of the P component of the light wave p They are:

[0100]

[0101]

[0102] According to the Fresnel formula, when the incident light is reflected and refracted on the interface, the polarization state of the reflected light and the refracted light will change. The polarization degree of the refracted light is expressed as follows: According to the above formula, the polarization degree of the refracted light p can be obtained. t With the target refractive index n and the incident angle θ i The relationship between them is:

[0103]

[0104] Then, using the law of refraction, the incident angle θ i And the refraction angle θ is converted. The refraction angle θ is the normal zenith angle. According to Fresnel's law, the normal zenith angle θ can be expressed as:

[0105]

[0106] The detailed model of the normal azimuth is:

[0107]

[0108] z(x,y) is the three-dimensional surface restoration function of the ground object. The form of z(x,y) in the frequency domain is z(u,ν), and z(u,ν) is as follows:

[0109]

[0110] Among them, z(u,ν) is the form of z(x,y) in the frequency domain, N and M represent the two dimensions of the surface array ground object image, and the number of pixels in the length and width directions of the instantaneous ground object polarization information image, respectively. They are The expression in the frequency domain. F{·} represents Fourier transform, F -1 {·} represents the inverse Fourier transform; x and y are the coordinates of any point in the 3D terrain. The time-varying 3D terrain shape can be obtained using z(x,y).

[0111] A schematic diagram of the mechanism of establishing a polarization 3D imaging model for an instantaneous passive array 3D imaging method of a time-varying terrain object according to the present invention is shown in FIG. Figure 3 As shown. Polarization 3D imaging mainly uses the relationship between the surface normal of the object and the polarization degree of the light reflected from the object surface to achieve the reconstruction of the 3D shape of the object. According to the reflection law and refraction law of light waves, the propagation direction of the light wave on the surface of the object is determined by the incident direction of the light wave and the shape of the target surface. The Fresnel formula and the definition of polarization degree give the relationship between the polarization degree of the light reflected from the object surface and the incident direction of the light wave. Therefore, the incident direction information of the light wave can be obtained based on the polarization degree of the light reflected from the object surface. Figure 3As shown in the figure, the light beam is reflected after it hits the surface of the object to be reconstructed. According to the law of reflection of light, the incident angle of the incident light is equal to the reflection angle, which is equal to the angle θ in the figure. The propagation direction of the reflected light is the z-axis, and the plane where the detector of the polarization 3D imaging device is located is the xoy plane. The normal line of the surface of the object to be reconstructed is The projection on the xoy plane is The angle with the x-axis is The angle of the linear polarization direction relative to the reference direction in the polarization 3D imaging device is θ pol . It is the normal azimuth angle between the projection of the exit surface in the image plane and the x-axis in the image plane.

[0112] A schematic diagram of surface normal polar coordinates of a method for instantaneous passive area array 3D imaging of time-varying terrain objects according to the present invention is shown in FIG. Figure 4 In order to more intuitively represent the surface normal of the object to be reconstructed and the incident angle θ and the incident azimuth The relationship between Figure 3 China-France Line Indicates Figure 4 As shown, the incident angle θ is the zenith angle of the normal, and the incident azimuth angle is is the polarization angle of the normal. The normal zenith angle θ and the incident azimuth angle Together they determine the surface normal of the object to be reconstructed, and its expression is:

[0113]

[0114] The right-handed rectangular coordinate system is established with the center of the unit block as the origin. The positive direction of the z-axis is perpendicular to the surface of the unit block and upward. The x-axis and the y-axis are parallel to the length and width directions of the pixel in the ground object polarization information image, respectively. x Represents the normal vector The component in the x-axis direction, N y Represents the normal vector The component in the y-axis direction, N z Represents the normal vector Component in the z-axis direction.

[0115] As shown in Figure 6(a)(b), the relationship between the Stokes vector and the polarization ellipse shows that the polarization angle of the polarization ellipse is the polarization angle of the reflected light (i.e. incident azimuth angle). Figure 3 As shown, the polarization angle of the reflected light is the azimuth angle of the incident light.

[0116] This invention enables instantaneous, area-based, three-dimensional monitoring of terrain features in areas corresponding to geological hazards such as collapses, landslides, debris flows, and barrier lakes, as well as safety production targets such as tailings pond monitoring. This information, combined with the image and height information, can be transmitted to emergency disaster relief departments, providing data support for disaster assessment, mitigation, and rescue efforts. The invention is applicable to the three-dimensional monitoring of time-varying terrain features, as well as the three-dimensional imaging of other continuously changing terrain features. It can also be used for the three-dimensional imaging of satellites and celestial bodies in relative motion in space, the three-dimensional monitoring of tunnel wall deformation, and the three-dimensional reconstruction of translucent objects.

[0117] The present invention can be deployed on space-based or airborne platforms, enabling large-scale, long-term monitoring of time-varying terrain features through networking. Leveraging the platform's lateral maneuverability, it can achieve long-term, large-scale monitoring of time-varying terrain features while reducing the number of network components required. By utilizing information from multiple linear polarization directions of time-varying terrain features and using polarization-based three-dimensional imaging methods, instantaneous, planar, and three-dimensional information can be obtained. This information can be used to monitor time-varying geological disasters, production safety, and other targets, facilitating disaster assessment and post-disaster relief efforts.

[0118] Although the present invention has been disclosed as above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention are within the scope of protection of the technical solutions of the present invention. In the absence of conflict, the embodiments of the present application and the technical features in the embodiments can be combined with each other.

[0119] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A method for instantaneous passive area array 3D imaging of time-varying terrain, characterized by: Imaging the target area to obtain a ground object polarization information image; the ground object polarization information image is composed of a plurality of unit blocks; The obtained ground object polarization information image is used to extract light intensity information and obtain the ground object polarization information corresponding to each unit block; The polarization information of ground objects includes: polarization degree p and polarization angle Based on the obtained polarization degree p and the polarization degree value ranges of different ground object types, the ground object polarization information image is divided into multiple regions, and the unit blocks in the same region belong to the same ground object type; the refractive index information n corresponding to each unit block is obtained through the refractive index n corresponding to the ground object type; the complex ground object classification is performed using polarization degree, including determining the correspondence between ground object type and polarization degree range in geological disaster areas through field measurements, and combining the pixel-level ground object polarization degree information obtained by solving the ground object polarization information characteristics to perform pixel-level ground object classification; Using the obtained ground object polarization information and the obtained refractive index information n, the ground object gradient field N corresponding to each unit block is obtained x 、N y 、N z ; By using the ground object gradient field corresponding to each unit block, the three-dimensional surface restoration function of the ground object is determined, thereby obtaining the three-dimensional morphology of the time-varying ground object; A polarization information image of a ground object is obtained using a polarization 3D imaging device, wherein the polarization 3D imaging device uses polarized light reflected or radiated by the ground object to perform polarization 3D imaging of the ground object; the polarization 3D imaging device is a planar array imaging remote sensor, and the imaging area is greater than 100 square kilometers; The polarization three-dimensional imaging device consists of a high-polarization-maintaining optical lens, multi-aperture polarization in the same field of view / single-aperture rotating multi-linear polarization direction polarization / focus plane polarization components, and a polarization three-dimensional reconstruction component. It can simultaneously obtain information on three or four linear polarization directions; it adopts visible and infrared working modes to achieve all-day imaging; and it uses array detection devices to achieve array imaging of ground objects.

2. The instantaneous passive area array 3D imaging method of time-varying terrain according to claim 1, characterized in that: The land feature types include: grassland, trees, gravel and soil, water bodies, and shrubs.

3. The instantaneous passive area array 3D imaging method for time-varying terrain features according to claim 1, characterized in that: The method for obtaining the polarization information of the ground object corresponding to each unit block is as follows: Using the obtained ground object polarization information image, light intensity information in multiple different linear polarization directions in each unit block is obtained; Determine the Stokes vector S based on the obtained light intensity information; According to the determined Stokes vector S, the polarization degree p and polarization angle corresponding to each unit block are obtained As ground object polarization information.

4. The instantaneous passive area array 3D imaging method for time-varying terrain according to claim 3, characterized in that: Each unit block consists of 2 by 2 pixels; each unit block can provide light intensity information in 3 or 4 linear polarization directions.

5. The instantaneous passive area array 3D imaging method of time-varying terrain according to claim 4, characterized in that: Each unit block can provide light intensity information with linear polarization directions of 0°, 45°, 90°, and 135° (I 0° , I 45° , I 90° , I 135° ).

6. The instantaneous passive area array 3D imaging method of time-varying terrain according to claim 5, characterized in that: The method for determining the Stokes vector S is as follows: Among them, I, Q and U are the three parameters of the Stokes vector S, I represents the total intensity of the light wave, Q represents the difference between the intensities of the linearly polarized light at 0° and 90°, and U represents the difference between the intensities of the linearly polarized light at 45° and 135°.

7. The instantaneous passive area array 3D imaging method of time-varying terrain according to claim 4, characterized in that: Each unit block can provide light intensity information with linear polarization directions of 0°, 45° and 90° (I 0° , I 45° , I 90° ).

8. The instantaneous passive area array 3D imaging method of time-varying terrain according to claim 7, characterized in that: The method for determining the Stokes vector S is as follows: Among them, I, Q and U are the three parameters of the Stokes vector S, I represents the total intensity of the light wave, Q represents the difference between the intensities of the linearly polarized light at 0° and 90°, and U represents the difference between the intensities of the linearly polarized light at 45° and 135°.

9. The instantaneous passive area array 3D imaging method of time-varying terrain according to claim 4, characterized in that: Each unit block can provide light intensity information with linear polarization directions of 0°, 60° and 120° (I 0° , I 60° , I 120° ).

10. The instantaneous passive area array 3D imaging method of time-varying terrain according to claim 9, characterized in that: The method for determining the Stokes vector S is as follows: Among them, I, Q and U are the three parameters of the Stokes vector S, I represents the total intensity of the light wave; Q represents the linearly polarized light component in the horizontal direction; and U represents the linearly polarized light component in the 45° direction.

11. The instantaneous passive area array three-dimensional imaging method of time-varying terrain according to any one of claims 6, 8 and 10, characterized in that: The method for determining the polarization degree p is specifically as follows:

12. The instantaneous passive area array 3D imaging method of time-varying terrain according to any one of claims 6, 8 and 10, characterized in that: The polarization angle The method for determining is as follows:

13. The instantaneous passive area array three-dimensional imaging method of time-varying terrain according to any one of claims 1 to 10, characterized in that: Get the ground object gradient field N corresponding to each unit block x 、N y 、N z The method is as follows: Determine the normal zenith angle θ according to the obtained polarization degree p and the obtained refractive index information n; According to the determined normal zenith angle θ and the obtained polarization angle Determine the ground object gradient field N corresponding to each unit block x 、N y 、N z .

14. The instantaneous passive area array 3D imaging method of time-varying terrain according to claim 13, characterized in that: The method for determining the normal zenith angle θ is specifically as follows:

15. The instantaneous passive area array three-dimensional imaging method of time-varying terrain according to claim 13, characterized in that: Determine the ground object gradient field N corresponding to each unit block x 、N y 、N z The method is as follows: The right-handed rectangular coordinate system is established with the center of the unit block as the origin. The positive direction of the z-axis is perpendicular to the surface of the unit block and upward. The x-axis and the y-axis are parallel to the length and width directions of the pixel in the ground object polarization information image, respectively. x Represents the normal vector The component in the x-axis direction, N y Represents the normal vector The component in the y-axis direction, N z Represents the normal vector Component in the z-axis direction.

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