Method and system for enhancing expression of terrain intervisibility information in aerial panoramic image

Abstract

The invention belongs to the technical field of panoramic image information enhancement, and discloses a terrain intervisibility information enhancement expression method and a terrain intervisibility information enhancement expression system in an aerial panoramic image. Converting the two-dimensional coordinates into spherical longitude and latitude coordinates, converting the spherical longitude and latitude coordinates into ground point spherical image space coordinates in combination with image depth information, converting panoramic image pose data into ground point space rectangular coordinates, calculating intervisibility information, and differentially expressing intervisibility and non-intervisibility areas according to colors; and returning the coordinate value with the intervisibility color information to the corresponding panoramic image to realize topographic feature fusion expression. The intervisibility relationship enhancement expression is concise and clear, the rendered curved surface is accurately matched with the image scene, and a certain three-dimensional effect is achieved; through comprehensive research and judgment of an intervisibility relationship analysis result and a real scene of an analysis area, an on-site environment condition can be better understood.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of panoramic image information enhancement, and in particular to a method and system for enhancing the expression of terrain visibility information in aerial panoramic images. BACKGROUND

[0002] Panoramic images can provide a full field of view experience consistent with the real world, improve the visual fidelity of virtual geographic environments, and become a new research hotspot in many fields such as smart cities and environmental monitoring. However, terrain visibility information cannot be expressed in three-dimensional form in two-dimensional maps, and how to enhance the expression of terrain visibility information in panoramic images has become one of the difficult problems in current research. SUMMARY

[0003] The present application proposes a method and system for enhancing the expression of terrain visibility information in aerial panoramic images to address the problem of insufficient expression of three-dimensional spatial features of terrain undulations in panoramic images. The present application extracts the depth information and two-dimensional coordinates of the panoramic image with depth information, respectively, and then converts the two-dimensional coordinates to spherical latitude and longitude coordinates and combines the image depth information to convert to ground point spherical image space coordinates. The panoramic image pose data is converted to ground point space rectangular coordinates, the visibility information is calculated, and the visible and non-visible areas are expressed according to the color, and the coordinate values with color information are returned to the corresponding panoramic image to realize the fusion expression of terrain features. The fusion display of color and visibility information can be realized in a virtual geographic scene.

[0004] To achieve the above purpose, the present application adopts the following technical scheme: The first aspect of the present application provides a method for enhancing the expression of terrain visibility information in aerial panoramic images, comprising: Step 1: Depth information and two-dimensional coordinate extraction First, a panoramic image containing depth information is obtained using professional equipment or algorithms. This image not only records two-dimensional image information of the scene, but also contains depth values corresponding to each pixel. Then, the image depth information and two-dimensional coordinates of the panoramic image are extracted through image processing techniques.

[0005] Step 2: Coordinate conversion to spherical latitude and longitude coordinates Based on the predefined correspondence between the two-dimensional coordinates of the panoramic image and the spherical coordinates, the extracted two-dimensional coordinates are converted to spherical latitude and longitude coordinates through mathematical transformation, laying the foundation for subsequent three-dimensional spatial coordinate conversion.

[0006] Step 3: Conversion of spherical latitude and longitude coordinates to ground point spherical image space coordinates Combining image depth information, using spherical geometry and projection principle, a conversion model between panoramic image spherical longitude and latitude coordinates and ground point spherical image space coordinates is established to realize accurate solution of three-dimensional space coordinates.

[0007] Step 4: spatial rectangular coordinate conversion According to the pose data (including position, attitude and other information) of the panoramic image, the ground point spherical image space coordinates are converted into ground point spatial rectangular coordinates by using spatial coordinate conversion principle, so as to facilitate subsequent visibility calculation.

[0008] Step 5: visibility information calculation The height value of the view point on the terrain surface and the elevation difference of all ground points between the connecting line of the view point and the target point are calculated to obtain the visibility information.

[0009] Step 6: visibility and color mapping The mapping relationship between visibility information and color is established, and the visible and invisible areas are expressed according to color.

[0010] Step 7: terrain feature fusion expression The coordinate values with visibility color information are mapped back to the corresponding panoramic image to realize visual fusion of terrain visibility features and original image, and to provide more intuitive and rich terrain information display for users.

[0011] Further, the step 2 comprises: The longitude and latitude coordinates (φ, θ) of the spherical projection point p' corresponding to the point p on the panoramic image are calculated in the following manner: Where (px, py) is the pixel coordinate of p, wd and ht are the length and width of the panoramic image respectively, θ and φ represent the zenith angle and azimuth angle on the spherical surface respectively, and θ is the angle with the y-axis.

[0012] Further, the step 3 comprises: The ground point spherical image space coordinates (x, y, z) are obtained in the following manner: Where d represents the image depth, and r represents the radius of the spherical coordinate system.

[0013] Further, the step 4 comprises: The ground point spatial rectangular coordinates (X, Y, Z) are calculated in the following manner: Where R is an orthogonal matrix determined by the rotation angle, and T represents transposition. ,​​ , represents the camera position information.

[0014] Further, the step 5 comprises: Step 5.1: based on the ground point space rectangular coordinates, calculating the ground point elevation of each point on the connecting line between the view point and the target point on the terrain surface; Step 5.2: judging the relationship between the ground point elevation and the connecting line elevation under the same coordinates to obtain the visibility information.

[0015] Further, the step 5.1 comprises: making the connecting line between the view point (x v , y v ) and the target point (x t , y t ), and the straight line is described as y = kx + b, k ∈ [0, 1], b represents the y-axis intercept of the straight line, when increasing one unit along the x-axis, that is, x v+1 = x v + 1, the y-axis direction increases k size units, and the point position is selected in the following way: Where ω represents the vertical error between the currently selected integer y coordinate and the theoretical perfect straight line y-axis coordinate, ω ∈ [-0.5, 0.5]; Let the error in the process of judging y i+1 be ω new , then: Let dx = x t - x v , multiply both sides by dx, and let = dx·ω, then: Through the above way, all DEM grid center points passed by the connecting line between the view point and the target point are obtained, and then the ground point elevation corresponding to the DEM grid is obtained.

[0016] Further, the step 5.2 comprises: Judging the relationship between the ground point elevation and the connecting line elevation under the same coordinates, if there is any ground point whose elevation is greater than the connecting line elevation at this position, the view point cannot observe the target point, otherwise the target point can be observed.

[0017] The second aspect of the application provides a terrain visibility information enhanced expression system in an aerial panoramic image, comprising: The depth information and two-dimensional coordinate extraction module is used for obtaining panoramic images with depth information and extracting image depth information and two-dimensional coordinates respectively. The first coordinate conversion module is used for converting coordinates according to the corresponding relationship between the two-dimensional coordinates of the panoramic image and the spherical coordinates to obtain spherical longitude and latitude coordinates. The second coordinate conversion module is used for converting coordinates through the corresponding relationship between the spherical longitude and latitude coordinates of the panoramic image and the spherical image space coordinates of the ground points and combining the image depth information to obtain the spherical image space coordinates of the ground points. The third coordinate conversion module is used for converting the spherical image space coordinates of the ground points according to the pose data of the panoramic image to obtain the space rectangular coordinates of the ground points. The line-of-sight information calculation module is used for calculating the elevation difference of all ground points of the line between the height value of the view point on the terrain surface and the target point to obtain the line-of-sight information. The line-of-sight and color mapping module is used for establishing the mapping relationship between the line-of-sight information and the color, and expressing the visible area and the non-visible area according to the color. The terrain feature fusion expression module is used for returning the coordinate values with the line-of-sight color information to the corresponding panoramic image to realize the fusion expression of the terrain features.

[0018] The third aspect of the present application provides an electronic device, including a memory, a processor and a computer program stored on the memory and executable on the processor, and the processor executes the computer program to realize the method of any one of the above.

[0019] The fourth aspect of the present application provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to realize the method of any one of the above.

[0020] Compared with the prior art, the present application has the beneficial effects: The present application extracts the depth information and two-dimensional coordinates of the panoramic image with depth information, converts the two-dimensional coordinates into spherical longitude and latitude coordinates and combines the image depth information to convert into the spherical image space coordinates of the ground points, converts the spherical image space coordinates of the ground points into the space rectangular coordinates of the ground points by using the pose data of the panoramic image, calculates the line-of-sight information, expresses the visible area and the non-visible area according to the color, and returns the coordinate values with the line-of-sight color information to the corresponding panoramic image to realize the fusion expression of the terrain features. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 A spherical longitude and latitude coordinate diagram provided for an embodiment of the present application; Figure 2 A three-dimensional rectangular coordinate system diagram provided for an embodiment of the present application; Figure 3 One of a flowchart of a method for enhancing expression of terrain visibility information in an aerial panoramic image provided for an embodiment of the present application; Figure 4 One of a flowchart of a method for enhancing expression of terrain visibility information in an aerial panoramic image provided for an embodiment of the present application; Figure 5 One of a flowchart of a method for enhancing expression of terrain visibility information in an aerial panoramic image provided for an embodiment of the present application; Figure 6 A diagram showing the relationship between two-dimensional coordinates and spherical coordinates provided for an embodiment of the present application; Figure 7 A spherical longitude and latitude coordinate mapping diagram provided for an embodiment of the present application; Figure 8 A diagram showing the principle of visibility information calculation provided for an embodiment of the present application; Figure 9 An example diagram of enhanced results of visibility analysis provided for an embodiment of the present application; Figure 10 A system architecture diagram of a system for enhancing expression of terrain visibility information in an aerial panoramic image provided for an embodiment of the present application. DETAILED DESCRIPTION

[0022] For the convenience of understanding, some of the terms appearing in the specific embodiments of the present application are explained as follows: Depth image: A depth image is an image or image channel containing information about the distance from the surface of a scene object to the viewpoint.

[0023] Two-dimensional coordinates: In this patent, it refers to the coordinates established for representing the pixel coordinates in a panoramic image; Spherical longitude and latitude coordinates: It is a method for representing the position of any point in a panoramic image. It consists of two coordinates, longitude and latitude, which together determine the exact position of a point on the surface of a panoramic image. As shown in Figure 1 .

[0024] Three-dimensional rectangular coordinate system (three-dimensional Cartesian coordinate system): The three-dimensional rectangular coordinate system is formed on the basis of the two-dimensional Cartesian coordinate system according to the right-hand rule by adding a third coordinate (i.e. Z-axis). As shown in Figure 2 .

[0025] Panorama image pose parameters: panorama image pose parameters include position parameters and attitude parameters. The position parameters describe the specific position of the panorama image in space, and the attitude parameters describe the orientation and attitude of the panorama image.

[0026] Ground point space rectangular coordinate system: the ground point space rectangular coordinate system takes the earth center as the coordinate origin, takes the reference ellipsoid rotation axis as the Z axis, and takes the reference ellipsoid equatorial plane as the XY plane. The intersection line of the equatorial plane and the prime meridian on the reference ellipsoid is the X axis, and the direction pointing to the prime meridian is the positive direction. The Y axis is located on the equatorial plane and forms a right-handed rectangular coordinate system with the X axis and the Z axis.

[0027] The application will be further explained in combination with the drawings and specific embodiments: As shown in Figure 3 and Figure 4 A method for enhancing the expression of terrain visibility information in aerial panorama images, comprising: Step one: obtain panorama images with depth information and extract image depth information and two-dimensional coordinates respectively; Step two: coordinate conversion is performed according to the corresponding relationship between the two-dimensional coordinates of the panorama image and the spherical coordinates to obtain spherical longitude and latitude coordinates; Step three: through the corresponding relationship between the spherical longitude and latitude coordinates of the panorama image and the ground point spherical image space coordinates and combining the image depth information, coordinate conversion is performed to obtain the ground point spherical image space coordinates; Step four: according to the pose data of the panorama image, the ground point spherical image space coordinates are converted to obtain the ground point space rectangular coordinates; Step five: the elevation difference of all ground points between the height value of the view point on the terrain surface and the target point is calculated by using the ground point space rectangular coordinates to obtain the visibility information; Step six: a mapping relationship between the visibility information and the color is established, and the visible area and the non-visible area are expressed according to the color; Step eight: the coordinate values with visibility color information are returned to the corresponding panorama images to realize the fusion expression of terrain features.

[0028] The present application extracts the depth information and two-dimensional coordinates of the panoramic image according to the depth information of the panoramic image, then converts the two-dimensional coordinates into spherical longitude and latitude coordinates and combines the image depth information to convert into ground point spherical image space coordinates, converts the panoramic image pose data into ground point space rectangular coordinates, calculates the visibility information, and expresses the visible and non-visible areas according to the color, returns the coordinate values with the visibility color information to the corresponding panoramic image to realize the terrain feature fusion expression. The terrain feature enhanced expression can be roughly divided into two parts: the first part is terrain feature analysis, which calculates the ground point coordinates from the pixel points and depth information, and extracts the terrain features by using different terrain analysis algorithms; the second part is terrain feature fusion expression, which reasonably expresses the terrain features on the selected area of the panoramic image.

[0029] Specifically, as shown in Figure 5 A high-precision three-dimensional model construction method based on point cloud data, the main technical process is as follows: Step 1: Extract the depth information and two-dimensional coordinates of the panoramic image.

[0030] Step 1.1: Use professional equipment or algorithms to obtain panoramic images containing depth information. This image not only records the two-dimensional image information of the scene, but also contains the depth value corresponding to each pixel point.

[0031] Step 1.2: Extract the image depth information and two-dimensional coordinates of the panoramic image by image processing technology.

[0032] Step 2: Convert the two-dimensional coordinates to spherical longitude and latitude coordinates.

[0033] Step 2.1: Based on the pre-defined mapping relationship between the two-dimensional coordinates of the panoramic image and the spherical coordinates (as shown in Figure 6 ), a mathematical transformation model is constructed.

[0034] In the display technology of panoramic images, the information of two-dimensional plane images is directly mapped to a virtual spherical surface to realize the visual display of three-dimensional space. This mapping process establishes a corresponding relationship from the two-dimensional plane coordinate system to the spherical coordinate system. Specifically, each pixel point in the panoramic image is regarded as a vector, which starts from the center of the sphere and points to a certain point on the surface of the sphere, which has a certain longitude and latitude value in the spherical coordinate system. Through this mapping, the image information originally represented in two-dimensional plane is transformed into spatial distribution on three-dimensional sphere, thereby realizing the stereoscopic display of panoramic image. In the spherical projection system of panoramic image, the content of the plane panoramic image from left to right (i.e. from the leftmost to the rightmost) is equivalent to the content from -180° to +180° in the horizontal field of view of the observer. At the same time, the content of the plane panoramic image from top to bottom (i.e. from the topmost to the bottommost) is equivalent to the content from +90° to -90° in the vertical field of view of the observer.

[0035] Step 2.2: Using the above model, the extracted two-dimensional coordinates are converted into spherical latitude and longitude coordinates, providing a basis for subsequent three-dimensional space coordinate conversion.

[0036] For two-dimensional coordinates on a plane, let the pixel coordinates of a point p on the plane panoramic image be (px, py), and the length and width of the plane panoramic image be wd and ht, respectively. The corresponding zenith angle θ and azimuth angle φ on the sphere can be mapped out. As shown in Figure 7 .

[0037] Then the pixel latitude and longitude coordinates (x, y) of the spherical projection point p' of P can be obtained. The formula for calculating (x, y) is: The zenith angle θ of this is the angle between y and y, that is, θ is not the value from 0 to y on the two-dimensional coordinate system as we usually understand, but the value from π / 2 to y, which can be understood as equal to the value of the py segment.

[0038] Third step, spherical latitude and longitude coordinates to ground point spherical image space coordinate conversion.

[0039] Step 3.1: Combined with image depth information, a conversion model between panoramic image spherical latitude and longitude coordinates and ground point spherical image space coordinates is established using spherical geometry and projection principles, realizing accurate solution of three-dimensional space coordinates.

[0040] Step 3.2: Through the model, accurate solution of three-dimensional space coordinates is realized, providing accurate data for subsequent visibility calculation. According to the image depth d, the spherical image space coordinates (x, y, z) of the ground point P can be obtained: Where r represents the radius of the spherical coordinate system.

[0041] Fourth step, space rectangular coordinate conversion.

[0042] Step 4.1: According to the pose data of the panoramic image (including position X S , Y S , Z S , attitude α, ω, β, etc.), a conversion matrix is constructed using space coordinate transformation principles.

[0043] Step 4.2: Using the conversion matrix, the ground point spherical image space coordinates are converted into ground point space rectangular coordinates, which is convenient for subsequent visibility calculation.

[0044] According to the obtained panoramic image pose parameters (X S , Y S ​​, Z S , α, ω, β), the ground point P space rectangular coordinates (X, Y, Z) are obtained: Wherein, R is an orthogonal matrix determined by the rotation angle (including the yaw angle α, the pitch angle ω and the roll angle β), which describes the process of rotating the object space coordinate system to the spherical image space coordinate system. According to the property of the orthogonal matrix , so the above formula can be used. 、 、 represents the camera position information (in the object space coordinate system).

[0045] Step 5, the visibility information is calculated.

[0046] Step 5.1: Based on the ground point space rectangular coordinates, the ground point elevation of each point on the line between the view point and the target point on the terrain surface is calculated.

[0047] The line between the view point (x v , y v ) and the target point (x t , y t ) is drawn, and the straight line is described as y = kx + b (k ∈ [0, 1]). When increasing one unit along the x-axis, that is, x v+1 = x v + 1, the y-axis direction increases by k units. Since this algorithm is based on integer operation, there is an error ω (ω ∈ [-0.5, 0.5]) less than one-half unit of the y-axis in the point judgment, at which time y i+1 = y i +1 or y i+1 = y i , and the selection principle is that k + ω complies with rounding, as shown in Figure 8 , which is expressed as: Let the error in judging y i+1 be ω new , then: Let dx = x t - x v , multiply both sides by dx, and let = dx·ω, then: All DEM grid center points through which the line between the view point and the target point passes are obtained by the above method, and the ground point elevations corresponding to all grid center points are obtained.

[0048] Step 5.2: Determine the relationship between the elevation of the ground point through which the line passes and the elevation of the line at the same coordinates, i.e. the visibility information.

[0049] Whether the view point and the target point are visible depends on whether there are any obstacles blocking the line of sight on the line connecting the two points. Connect the view point V and the target point T, and determine the relationship between the elevation of the ground point through which the line passes and the elevation of the line at the same coordinates. If there is any ground point whose elevation is greater than the elevation of the line at that point, the view point V cannot observe the target point T, otherwise it can.

[0050] Get the grid point elevation TerrainElev of the DEM grid through which the line of sight passes. If TerrainElev is null, it is assumed that this point is visible, and the next point is judged. Otherwise, compare the size of the view elevation ViewElev at the same horizontal position. If TerrainElev > ViewElev, it is not visible and the calculation is ended. Otherwise, the next point is judged. When the grid point elevation of all DEM grids through which the line of sight passes is determined to be less than the view point elevation, the view point can see the target point.

[0051] Step 6, visibility information and color mapping.

[0052] Step 6.1: Establish a mapping relationship between visibility information and color. If the two points are visible, the symbol color is green, and if they are not visible, the symbol color is red.

[0053] The visibility relationship enhances the expression using point and line symbols, and uses color to represent whether it is visible or not. The point symbol represents the selected ground point, which is superimposed on the selected pixel point, with appropriate size and no fill color. The line symbol connects two point symbols to represent the direction of the line of sight in three-dimensional space, with appropriate width. If the two points are visible, the symbol color is green, and if they are not visible, the symbol color is red. When multiple directions are used to determine the visibility relationship, it can be converted to visibility domain analysis.

[0054] Step 6.2: According to the visibility information, assign appropriate colors to the visible and non-visible areas to realize the visual expression of the visibility information.

[0055] Step 7, terrain visibility information fusion expression.

[0056] Step 7.1: Map the coordinate values with visibility color information back to the corresponding panoramic image.

[0057] Step 7.2: Through image processing technology, realize the visual fusion of terrain visibility features and original image, and provide more intuitive and rich terrain information display for users.

[0058] Select different shooting height of aerial panoramic image, the observation point in different environment visibility situation experiment, the experimental results are good, such as Figure 9 As shown in the figure. Figure 9 In (a), the observation point is on the slope, Figure 9 In (b), the observation point is in the valley, Figure 9 In (c), and Figure 9 In (d), the observation point is on the relatively flat ground. The visibility relationship is a kind of qualitative terrain feature, so red and green are used to represent whether the observation point and the target point are visible. The visibility relationship enhances the expression of simplicity and clarity, the rendering curve is matched with the image scene accurately, and there is a certain stereoscopic effect. And users can better understand the actual environment by comprehensively analyzing the visibility analysis results and the real scene of the analysis area.

[0059] On the basis of the above embodiment, as Figure 10 The present application also provides a terrain visibility information enhanced expression system in aerial panoramic image, which comprises: A depth information and two-dimensional coordinate extraction module is used to obtain panoramic image with depth information and extract image depth information and two-dimensional coordinates respectively; A first coordinate conversion module is used to convert the two-dimensional coordinates of the panoramic image into spherical latitude and longitude coordinates according to the corresponding relationship between the two-dimensional coordinates and the spherical coordinates; A second coordinate conversion module is used to convert the spherical latitude and longitude coordinates of the panoramic image into ground point spherical image space coordinates by combining the image depth information according to the corresponding relationship between the spherical latitude and longitude coordinates and the ground point spherical image space coordinates; A third coordinate conversion module is used to convert the ground point spherical image space coordinates into ground point space rectangular coordinates according to the pose data of the panoramic image; A visibility information calculation module is used to calculate the elevation difference of all ground points on the connecting line between the height value of the observation point and the target point on the terrain surface to obtain the visibility information; A visibility and color mapping module is used to establish the mapping relationship between the visibility information and the color, and express the visible area and the invisible area according to the color; A terrain feature fusion expression module is used to return the coordinate values with visibility color information to the corresponding panoramic image to realize the fusion expression of terrain features.

[0060] On the basis of the above embodiment, the present application also provides an electronic device, which comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the method as described in steps one to seven and the method as described in the first step to the seventh step when executing the computer program.

[0061] On the basis of the above-mentioned embodiments, the application further proposes a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the method of steps one to seven and the method of first step to seventh step.

[0062] The above-mentioned is only the preferred embodiment of the application, it should be pointed out that, for the ordinary skilled in the art, without departing from the principles of the application, can also make a number of improvements and refinements, these improvements and refinements should also be considered as the protection scope of the application.

Claims

1. A method for enhancing the representation of terrain visibility information in aerial panoramic images, characterized in that, include: Step 1: Acquire panoramic images with depth information and extract image depth information and two-dimensional coordinates respectively; Step 2: Perform coordinate transformation based on the correspondence between the two-dimensional coordinates of the panoramic image and the spherical coordinates to obtain the spherical latitude and longitude coordinates; Step 3: Obtain the spherical image space coordinates of the ground points by performing coordinate transformation based on the correspondence between the spherical latitude and longitude coordinates of the panoramic image and the spherical image space coordinates of the ground points, combined with the image depth information; Step 4: Based on the pose data of the panoramic image, transform the spherical image space coordinates of the ground points to obtain the rectangular coordinates of the ground points; Step 5: Calculate the elevation difference between the viewpoint on the terrain surface and all ground points along the line connecting the viewpoint and the target point using the spatial rectangular coordinates of the ground points to obtain the line-of-sight information; Step 6: Establish the mapping relationship between visibility information and color, and use color to distinguish between visible and invisible areas; Step 7: Return the coordinate values ​​with visibility color information to the corresponding panoramic image to realize the fusion and expression of terrain features.

2. The method for enhancing terrain visibility information in aerial panoramic images according to claim 1, characterized in that, Step 2 includes: The latitude and longitude coordinates of the spherical projection point p' corresponding to point p on the panoramic image are calculated as follows: ,θ): Where (px, py) are the pixel coordinates of p, wd and ht are the length and width of the panoramic image, respectively, and θ and Let θ represent the zenith angle and azimuth angle on the sphere, respectively, and θ be the angle with the y-axis.

3. The method for enhancing the representation of terrain visibility information in aerial panoramic images according to claim 2, characterized in that, Step 3 includes: The spatial coordinates (x, y, z) of a ground point's spherical image are obtained as follows: Where d represents the image depth and r represents the radius of the spherical coordinate system.

4. The method for enhancing terrain visibility information in aerial panoramic images according to claim 3, characterized in that, Step 4 includes: Calculate the spatial rectangular coordinates (X, Y, Z) of a ground point as follows: Where R is an orthogonal matrix determined by the rotation angle, and T denotes the transpose. , , This indicates the camera's location information.

5. The method for enhancing terrain visibility information in aerial panoramic images according to claim 1, characterized in that, Step 5 includes: Step 5.1: Based on the spatial rectangular coordinates of ground points, calculate the ground elevation of each point on the line connecting the viewpoint and the target point on the terrain surface; Step 5.2: Determine the relationship between the elevation of the ground points the connecting line passes through and the elevation of the connecting line at the same coordinates to obtain the line-of-sight information.

6. A method for enhancing terrain visibility information in aerial panoramic images according to claim 5, characterized in that, Step 5.1 includes: Make viewpoint (x) v , y v ) to target point (x t , y t The line connecting the two points is described as y = kx + b, where k ∈ [0, 1], and b represents the y-intercept of the line. When the x-axis is increased by one unit, i.e., x... v+1 = x v When +1, the y-axis direction increases by k units, and the point selection is performed as follows: Where ω represents the perpendicular error between the currently selected integer y-coordinate and the y-axis coordinate of the theoretical perfect straight line, ω∈[-0.5, 0.5]; Let y be the judgment. i+1 The error in the process is ω new ,but: Let dx = x t - x v Multiply both sides by dx, and let = dx·ω, then: The above method is used to obtain all the center points of the DEM grids that the line connecting the viewpoint and the target point passes through, and then the ground point elevations corresponding to the DEM grids are obtained.

7. A method for enhancing terrain visibility information in aerial panoramic images according to claim 5, characterized in that, Step 5.2 includes: Determine the relationship between the elevation of the ground points the connecting line passes through and the elevation of the connecting line at the same coordinates. If the elevation of any ground point is greater than the elevation of the connecting line at that point, the viewpoint cannot observe the target point; otherwise, the target point can be observed.

8. A system for enhancing terrain visibility information in aerial panoramic images, characterized in that, include: The depth information and 2D coordinate extraction module is used to acquire panoramic images with depth information and extract image depth information and 2D coordinates respectively. The first coordinate transformation module is used to perform coordinate transformation to obtain spherical latitude and longitude coordinates based on the correspondence between the two-dimensional coordinates and spherical coordinates of the panoramic image; The second coordinate transformation module is used to obtain the spherical image space coordinates of the ground point by performing coordinate transformation through the correspondence between the spherical latitude and longitude coordinates of the panoramic image and the spherical image space coordinates of the ground point, combined with the image depth information. The third coordinate transformation module is used to transform the spherical image space coordinates of the ground points into rectangular coordinates of the ground points based on the pose data of the panoramic image. The line-of-sight information calculation module is used to calculate the elevation difference between the viewpoint on the terrain surface and all ground points along the line connecting the target point using the spatial rectangular coordinates of the ground points to obtain the line-of-sight information. The visibility and color mapping module is used to establish the mapping relationship between visibility information and color, and to distinguish between visible and invisible areas according to color. The terrain feature fusion and expression module is used to return coordinate values ​​with visibility color information to the corresponding panoramic image to achieve terrain feature fusion and expression.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the method as described in any one of claims 1 to 7.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the method as described in any one of claims 1 to 7.

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