Automatic cutting and mapping method and system for geological mineral map in three-dimensional space

Abstract

The invention discloses an automatic cutting and mapping method of a geological mineral map in three-dimensional space, comprising the following steps: S1, obtaining the four-corner coordinates of the geological mineral image mapping area input by the user; S2, sorting the four-corner coordinates into a clockwise convex quadrilateral Q; S3, finding the correct lower left corner point in the convex quadrilateral Q; S4, setting the lower left corner of the found convex quadrilateral Q as point a, and the points of the convex quadrilateral Q in clockwise order are a, b, c, and d; S5, establishing an image with a height of H and a width of W, setting the lower left corner point of the image as A, and the four-corner coordinates of the image in clockwise order are A, B, C, and D; S6, using perspective transformation and linear interpolation to transform the points a, b, c, and d of the convex quadrilateral Q to points A, B, C, and D, and completing the cutting and mapping of the geological mineral image. The invention can automatically and quickly cut and correct the perspective transformation of the geological mineral image in a way that meets human intuition.

Description

Technical Field

[0001] The invention relates to the field of geographic information software systems, and in particular to an automatic clipping and mapping method and system for geological mineral maps in three-dimensional space. Background Art

[0002] Limited by traditional working methods, traditional geological and mineral maps are almost all two-dimensional maps. In order to use traditional two-dimensional maps in modern three-dimensional systems, the most basic method is to rasterize geological and mineral maps and paste them as textures on three-dimensional models. Since geological and mineral maps are important materials for scientific research and engineering, the relative position of the textures and other elements in the three-dimensional scene (such as three-dimensional terrain) is crucial, so it is necessary to place the textures on the correct spatial coordinates according to a certain process method.

[0003] The most common mapping method in the field of real-time 3D technology is UV mapping. UV mapping describes which part of the texture should be attached to which polygon in the model. The vertices of each polygon are assigned to two-dimensional coordinates that define which part of the image is mapped. These two-dimensional coordinates are called UVs (compare them to XYZ coordinates in three dimensions). The operation of generating these UV maps is also called "unfolding" because it is like unfolding a mesh onto a two-dimensional plane. Usually the value range of the UV coordinate components is 0 to 1, the coordinates of the upper left corner of the map are (0, 0), and the lower right corner is (0, 1).

[0004] However, the mapping in the prior art faces a problem, that is, how to correspond the four corners of the mapping area with the four corners of the rectangular map. Because of the limitations of the map cutting method and coordinate projection, the mapping area of ​​the geological and mineral map is usually not a regular quadrilateral on the plane, but only a convex quadrilateral.

[0005] like Figure 1 As shown in the figure, abcd is transformed into ABCD, and the corresponding relationship intuitively judged by people should be Aa, Bb, Cc, Dd. For the left image, this corresponding relationship is also very simple to express mathematically, that is, the largest Y coordinate corresponds to A, the smallest X coordinate corresponds to B, the smallest Y coordinate corresponds to C, and the largest X coordinate corresponds to D. However, for the right figure, according to the above method, A will correspond to d, which goes against people's intuition.

[0006] The problem is described in geometric language, that is, for any convex quadrilateral ABCD in clockwise order, how to find the point of the "lower left corner" that meets people's intuition. Once the lower left corner point is found, the corresponding positions of other points are also determined.

[0007] This problem has been discussed in the field of image recognition, but there is no practical fully automatic processing solution. For example, someone on the CSDN website once proposed "first calculate the center position of the four points, and then make a judgment based on the center position. Then the center position is to add up the coordinates of all four points and divide it by 4. Then compare the y coordinate value of the point with the y value of the center point. The one that is greater than the y coordinate of the center point is at the bottom. The one that is less than the y coordinate of the center point is at the top. (x is to the right, and y is downward) After distinguishing the upper and lower points, separate the left and right points in the upper and lower point sets. The x coordinate is less than the center point, which is the left, and the x coordinate is greater than the center point, which is the right." After actual testing, this method has a high misjudgment rate, and the original author also pointed out that "the coordinate relationship arranged in this way sometimes needs to be rotated 90 degrees to meet our needs." However, this method cannot give when it is necessary to rotate 90 degrees. Only when the user sees that the processing result is contrary to intuition can they make a manual judgment.

[0008] In the math section of the StackExchange website, some people have proposed related solutions, but they are all similar to the above solution, that is, to determine the starting point by comparing the coordinate values ​​of the points. However, practice has proved that judgments made only by comparing the coordinate values ​​are unreliable. Summary of the invention

[0009] The main purpose of the present invention is to provide a method and system for automatic cropping and mapping of geological mineral maps in three-dimensional space, which can find the intuitive "lower left corner" of any convex quadrilateral, thereby realizing rapid cropping and perspective transformation correction of two-dimensional geological mineral maps, so that they can be mapped to the correct position in three-dimensional space.

[0010] The technical solution adopted by the present invention is:

[0011] A method for automatically cutting and mapping a geological mineral map in three-dimensional space is provided, comprising the following steps:

[0012] S1, obtaining the coordinates of the four corners of the geological and mineral image mapping area input by the user; wherein the coordinate system of the geological and mineral image is located with the right side as the positive X direction and the bottom as the positive Y direction;

[0013] S2. Sort the four corner coordinates into a clockwise convex quadrilateral Q, where the height of the convex quadrilateral Q is H and the width is W;

[0014] S3. Find the correct lower left corner point in the convex quadrilateral Q, which specifically includes the following steps:

[0015] Find the point L with the smallest horizontal coordinate X in the convex quadrilateral Q, and find the point B with the largest vertical coordinate Y;

[0016] 1) If point L is the same as point B, then point L is the lower left corner;

[0017] 2) If point L and point B are not adjacent points, then the previous point of point L is the bottom-left point;

[0018] 3) If the above conditions are not satisfied, then perform the following calculations:

[0019] i. Calculate the midpoint M1 of point L and point B, and calculate the midpoint M2 of the other two points in the convex quadrilateral Q;

[0020] ii. Calculate the vector difference V between midpoint M1 and midpoint M2, and calculate

[0021] where represents element-wise vector division, and <W, H> represents the vector composed of the scalar W and

[0022] H;

[0023] iii. If the length of the X component of V ′ is less than the length of the Y component, then point L is the bottom-left point; otherwise, point B is the bottom-left point;

[0024] S4. Let the bottom-left point of the found convex quadrilateral Q be point a, and the points of the convex quadrilateral Q in clockwise order be a, b, c, d;

[0025] S5. Establish an image with a height of H and a width of W, and let the bottom-left point of this image be A. The four-corner coordinates of this image in clockwise order are A, B, C, D;

[0026] S6. Use perspective transformation and linear interpolation to transform the points a, b, c, d of the convex quadrilateral Q to the points A, B, C, D, and complete the cropping and mapping of the geological and mineral image.

[0027] Continuing with the above technical solution, specifically use the ConvexHull function of Python GDAL to calculate the bottom-left point of the convex quadrilateral Q.

[0028] Continuing with the above technical solution, this method further includes step S7: overlay and display the cropped and mapped geological and mineral image in the three-dimensional engine in the form of a texture.

[0029] The present invention also provides an automatic cropping and mapping system for geological and mineral maps in three-dimensional space, including:

[0030] A four-corner coordinate acquisition module for geological and mineral images, which is used to acquire the four-corner coordinates of the mapping area of the geological and mineral image input by the user; wherein the right direction of the coordinate system where the geological and mineral image is located is the positive X direction, and the downward direction is the positive Y direction;

[0031] A calculation module, used for sorting the coordinates of the four corners into a clockwise convex quadrilateral Q by calculation, where the height of the convex quadrilateral Q is H and the width is W;

[0032] The lower left corner point finding module is used to find the correct lower left corner point in the convex quadrilateral Q, and specifically includes the following steps:

[0033] Find the point L with the smallest horizontal coordinate X in the convex quadrilateral Q, and find the point B with the largest vertical coordinate Y;

[0034] 1) If point L is the same as point B, then point L is the lower left corner;

[0035] 2) If point L and point B are not adjacent points, the previous point of point L is the lower left corner point;

[0036] 3) If the above conditions are not met, the following calculation is performed:

[0037] i. Calculate the midpoint M1 of point L and point B, and calculate the midpoint M2 of the other two points in the convex quadrilateral Q;

[0038] ii. Calculate the vector difference V between the midpoint M1 and the midpoint M2, and calculate

[0039] in represents element-wise vector division,<W,H> represents the vector composed of scalars W and H;

[0040] iii. If V ′ If the length of the X component is less than the length of the Y component, point L is the lower left corner; otherwise, point B is the lower left corner;

[0041] A setting module is used to set the lower left corner of the found convex quadrilateral Q as point a, and the points of the convex quadrilateral Q in clockwise order are a, b, c, and d;

[0042] The texture construction module is used to create an image with a height of H and a width of W. Let the lower left corner of the image be A. The coordinates of the four corners of the image are A, B, C, and D in clockwise order.

[0043] The transformation module is used to transform the points a, b, c, d of the convex quadrilateral Q to the points A, B, C, D using perspective transformation and linear interpolation, so as to complete the cropping and mapping of the geological mineral image.

[0044] In accordance with the above technical solution, it also includes an overlay module for overlaying the cropped and mapped geological and mineral images into a three-dimensional engine in the form of a texture and displaying them.

[0045] Following the above technical solution, the calculation module specifically uses the ConvexHull function of Python GDAL to calculate the convex hull of the four corner coordinates in a clockwise order.

[0046] The present invention also provides a computer storage medium, which stores a computer program that can be executed by a processor, and the computer program executes the automatic clipping and mapping method of geological mineral maps in three-dimensional space described in the above technical solution.

[0047] The beneficial effect of the present invention is that the present invention arranges the four-corner coordinates of the geological and mineral image mapping area input by the user into a clockwise convex quadrilateral, finds the point of the "lower left corner" of the convex quadrilateral that meets human intuition, thereby determining the corresponding positions of other corner points of the convex quadrilateral, and fills a complete computer image with the geological and mineral image through cropping and mapping, so that it can be accurately fitted to the correct geographic space position in three-dimensional space. It can be seen that the user only needs to specify the four-corner coordinates of a geological and mineral image mapping area without worrying about the specified order, and the mapping area can be automatically cropped and perspectively corrected in a way that meets human intuition. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 It is a schematic diagram of image cropping and mapping in the prior art;

[0050] Figure 2 It is a flow chart of a method for automatically cutting and mapping a geological mineral map in three-dimensional space according to an embodiment of the present invention;

[0051] Figure 3 yes Figure 2 Specific flow chart of step S3;

[0052] Figure 4 a is a schematic diagram of a convex quadrilateral with the smallest X coordinate and the largest Y coordinate;

[0053] Figure 5 It is a schematic diagram of a convex quadrilateral where point b has the largest X, point d has the largest Y, and a is the previous point of b in clockwise order;

[0054] Figure 6 It is a schematic diagram of a convex quadrilateral with the maximum X at point d, the maximum Y at point d, and the X length of M2-M1 less than the Y length;

[0055] Figure 7 is an original Juneau area geological mineral map in another embodiment of the present invention;

[0056] Figure 8 This is a geological mineral map of the Juneau area after being cropped and mapped using the patented method. DETAILED DESCRIPTION

[0057] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0058] Example 1

[0059] like Figure 2 As shown, the automatic clipping and mapping method of the geological mineral map in three-dimensional space in this embodiment includes the following steps:

[0060] S1, obtaining the coordinates of the four corners of the geological and mineral image mapping area input by the user; wherein the coordinate system of the geological and mineral image is located with the right side as the positive X direction and the bottom as the positive Y direction;

[0061] S2. Sort the four corner coordinates into a clockwise convex quadrilateral Q, where the height of the convex quadrilateral Q is H and the width is W;

[0062] S3. Find the correct lower left corner point in the convex quadrilateral Q;

[0063] S4. Let the lower left corner of the found convex quadrilateral Q be point a. The points of the convex quadrilateral Q in clockwise order are a, b, c, and d.

[0064] S5. Create an image with a height of H and a width of W. Let the lower left corner of the image be A. The coordinates of the four corners of the image are A, B, C, and D in clockwise order.

[0065] S6. Use perspective transformation and linear interpolation to transform points a, b, c, d of the convex quadrilateral Q to points A, B, C, D to complete the cropping and mapping of the geological mineral image.

[0066] Among them, Figure 3 As shown, step S3 specifically includes the following steps:

[0067] Find the point L with the smallest horizontal coordinate X in the convex quadrilateral Q, and find the point B with the largest vertical coordinate Y;

[0068] 1) If point L is the same as point B, then point L is the lower left corner, such as Figure 4 The situation shown;

[0069] 2) If point L and point B are not adjacent points, the previous point of point L is the lower left corner point, such as Figure 5 The situation shown;

[0070] 3) If the above conditions are not met, such as Figure 6 For the situation shown, the following calculations are performed:

[0071] i. Calculate the midpoint M1 of point L and point B, and calculate the midpoints of the other two points in the convex quadrilateral Q

[0072] M2;

[0073] ii. Calculate the vector difference V between the midpoint M1 and the midpoint M2, and calculate where denotes element-wise vector division, and <W, H> denotes a vector composed of scalars W and H;

[0074] iii. If the length of the X component of V ′ is less than the length of the Y component, then point L is the lower left corner point; otherwise, point B is the lower left corner point;

[0075] wherein in, W and H are two scalars, which together form a new vector <W, H>, and then the vector V and the vector <W, H> are subjected to element-wise division to obtain V'. Expanding it, we get V'.X = V.X / W, V'.Y = V.Y / H.

[0076] Finally, the cropped and mapped geological and mineral images are overlaid on the 3D engine in the form of textures and displayed. The specific texture mapping method can refer to the method in the applicant's patent "3D Space Real-time Overlay Method and System for Multi-source Heterogeneous Geological and Mineral Images".

[0077] Through the method of this embodiment, the user only needs to specify the four corner coordinates of the mapping area of a geological and mineral image without caring about the specified order, and the computer can automatically crop, map and fill the mapping area in a way that conforms to human intuition to form a complete computer image, so that it can be accurately fitted to the correct geographical space position in the 3D space.

[0078] Embodiment 2

[0079] This embodiment is based on Embodiment 1. Specifically, taking the geological and mineral map of the Juno area as an example, it is cropped and mapped using the method of this patent:

[0080] 1. The original resolution of the geological and mineral map image is 8840×4931. As Figure 7 shown, the four corner coordinates of its mapping area are (5876, 205), (168, 4586), (5895, 4567), (157, 220).

[0081] 2. Use Python GDAL's ConvexHull function to calculate the convex hull of the four corner coordinates. In clockwise order, the convex hull is (157, 220), (5876, 205), (5895, 4567), (5876, 205).

[0082] 3. Use the following Python code to sort the convex hull so that it starts from the lower left corner:

[0083]

[0084]

[0085]

[0086] The sorted results are (5876, 205), (157, 220), (5876, 205), (5895, 4567).

[0087] 4. Substitute the result of the previous step into the quad of the function below, and substitute the original address map into the image of the function below. The function code processed by Python OpenCV is as follows:

[0088]

[0089]

[0090] The resulting image is the cropped and mapped image, such as Figure 8 shown.

[0091] 5. Map the image obtained in the previous step in the 3D engine.

[0092] Example 3

[0093] This embodiment is mainly used to implement the above method embodiment. The automatic clipping and mapping system of geological mineral map in three-dimensional space of this embodiment mainly includes:

[0094] The four-corner coordinate acquisition module of the geological and mineral image is used to acquire the four-corner coordinates of the geological and mineral image mapping area input by the user; wherein the coordinate system of the geological and mineral image is located with the right as the positive X direction and the bottom as the positive Y direction;

[0095] A calculation module, used for calculating and sorting the four corner coordinates into a clockwise convex quadrilateral Q, where the height of the convex quadrilateral Q is H and the width is W;

[0096] The lower left corner point finding module is used to find the correct lower left corner point in the convex quadrilateral Q, and specifically includes the following steps:

[0097] Find the point L with the minimum abscissa X and the point B with the maximum ordinate Y in the convex quadrilateral Q;

[0098] 4) If the point L and the point B are the same point, then this point L is the lower left corner point;

[0099] 5) If the point L and the point B are not adjacent points, then the previous point of the point L is the lower left corner point;

[0100] 6) If the above conditions are not met, then perform the following calculations:

[0101] iv. Calculate the midpoint M1 of the point L and the point B, and calculate the midpoint M2 of the other two points in the convex quadrilateral Q;

[0102] v. Calculate the vector difference V between the midpoint M1 and the midpoint M2, and calculate

[0103] where represents element-wise vector division, and <W, H> represents the vector composed of the scalars W and H;

[0104] vi. If the length of the X component of V ′ is less than the length of the Y component, then the point L is the lower left corner point; otherwise, the point B is the lower left corner point;

[0105] A setting module, used to set the lower left corner of the found convex quadrilateral Q as the point a, and the points of the convex quadrilateral Q in clockwise order are a, b, c, d;

[0106] A texture mapping construction module, used to establish an image with a height of H and a width of W, set the lower left corner point of this image as A, and the four corner coordinates of this image in clockwise order are A, B, C, D;

[0107] A transformation module, used to transform the points a, b, c, d of the convex quadrilateral Q to the points A, B, C, D using perspective transformation and linear interpolation, and complete the cropping and mapping of the geological and mineral images.

[0108] Furthermore, the system further includes a superimposing module, used to superimpose the cropped and mapped geological and mineral images onto the 3D engine in the form of a texture and display them.

[0109] Furthermore, the calculation module specifically uses the ConvexHull function of Python GDAL to calculate the convex hull of the four corner coordinates and in clockwise order.

[0110] Example 4

[0111] The present application also provides a computer-readable storage medium, such as a flash memory, a hard disk, a multimedia card, a card-type memory (e.g., an SD or DX memory, etc.), a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), a programmable read-only memory (PROM), a magnetic memory, a disk, an optical disk, a server, an App application store, etc., on which a computer program is stored, and when the program is executed by a processor, a corresponding function is realized. When the computer-readable storage medium of this embodiment is executed by a processor, the automatic clipping and mapping method of a geological mineral map in three-dimensional space of the method embodiment is realized.

[0112] In summary, the present invention can find the intuitive "lower left corner" of any convex quadrilateral input by the user. The user only needs to specify the coordinates of the four corners of a geological mineral image mapping area without worrying about the order of specification, and the mapping area can be automatically cropped and mapped in an intuitive way to fill a complete computer image, so that it can be accurately fitted to the correct geographic space position in three-dimensional space.

[0113] It should be pointed out that, according to the needs of implementation, the various steps / components described in this application can be split into more steps / components, and two or more steps / components or partial operations of steps / components can be combined into new steps / components to achieve the purpose of the present invention.

[0114] The order of execution of each step in the above embodiment does not mean the order of execution. The order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present application.

[0115] It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should fall within the scope of protection of the appended claims of the present invention.

Claims

1. A method for automatic cutting and mapping of geological mineral maps in three-dimensional space, characterized in that: The following steps are involved: S1, obtaining the coordinates of the four corners of the geological and mineral image mapping area input by the user; wherein the coordinate system of the geological and mineral image is located with the right side as the positive X direction and the bottom as the positive Y direction; S2. Sort the four corner coordinates into a clockwise convex quadrilateral Q, where the height of the convex quadrilateral Q is H and the width is W; S3. Find the correct lower left corner point in the convex quadrilateral Q, which specifically includes the following steps: Find the point L with the smallest horizontal coordinate X in the convex quadrilateral Q, and find the point B with the largest vertical coordinate Y; 1) If point L is the same as point B, then point L is the lower left corner; 2) If point L and point B are not adjacent points, the previous point of point L is the lower left corner point; 3) If the above conditions are not met, the following calculation is performed: i. Calculate the midpoint M1 of point L and point B, and calculate the midpoint M2 of the other two points in the convex quadrilateral Q; ii. Calculate the vector difference V between the midpoint M1 and the midpoint M2, and calculate in represents element-wise vector division,<W,H> represents the vector composed of scalars W and H; iii. If the length of the X component of V' is less than the length of the Y component, point L is the lower left corner; otherwise, point B is the lower left corner; S4. Let the lower left corner of the found convex quadrilateral Q be point a. The points of the convex quadrilateral Q in clockwise order are a, b, c, and d. S5. Create an image with a height of H and a width of W. Let the lower left corner of the image be A. The coordinates of the four corners of the image are A, B, C, and D in clockwise order. S6. Use perspective transformation and linear interpolation to transform points a, b, c, d of the convex quadrilateral Q to points A, B, C, D to complete the cropping and mapping of the geological mineral image.

2. The automatic clipping and mapping method of geological mineral map in three-dimensional space according to claim 1 is characterized in that: Specifically, Python GDAL's ConvexHull function is used to calculate the convex hull of the four corner coordinates in a clockwise order.

3. The automatic cutting and mapping method of geological mineral map in three-dimensional space according to claim 1 is characterized in that: The method also includes step S7, superimposing the cropped and mapped geological mineral image into the three-dimensional engine in the form of a texture and displaying it.

4. An automatic cutting and mapping system for geological mineral maps in three-dimensional space, characterized in that: include: The four-corner coordinate acquisition module of the geological and mineral image is used to acquire the four-corner coordinates of the geological and mineral image mapping area input by the user; wherein the coordinate system of the geological and mineral image is located with the right as the positive X direction and the bottom as the positive Y direction; A calculation module, used for calculating and sorting the four corner coordinates into a clockwise convex quadrilateral Q, where the height of the convex quadrilateral Q is H and the width is W; The lower left corner point finding module is used to find the correct lower left corner point in the convex quadrilateral Q, and specifically includes the following steps: Find the point L with the smallest horizontal coordinate X in the convex quadrilateral Q, and find the point B with the largest vertical coordinate Y; 1) If point L is the same as point B, then point L is the lower left corner; 2) If point L and point B are not adjacent points, the previous point of point L is the lower left corner point; 3) If the above conditions are not met, the following calculation is performed: i. Calculate the midpoint M1 of point L and point B, and calculate the midpoint M2 of the other two points in the convex quadrilateral Q; ii. Calculate the vector difference V between the midpoint M1 and the midpoint M2, and calculate in represents element-wise vector division,<W,H> represents the vector composed of scalars W and H; iii. If the length of the X component of V' is less than the length of the Y component, point L is the lower left corner; otherwise, point B is the lower left corner; A setting module is used to set the lower left corner of the found convex quadrilateral Q as point a, and the points of the convex quadrilateral Q in clockwise order are a, b, c, and d; The texture construction module is used to create an image with a height of H and a width of W. Let the lower left corner of the image be A. The coordinates of the four corners of the image are A, B, C, and D in clockwise order. The transformation module is used to transform the points a, b, c, d of the convex quadrilateral Q to the points A, B, C, D using perspective transformation and linear interpolation, so as to complete the cropping and mapping of the geological mineral image.

5. The automatic cutting and mapping system for geological mineral map in three-dimensional space according to claim 4 is characterized in that: It also includes an overlay module, which is used to overlay the cropped and mapped geological and mineral images into the three-dimensional engine in the form of a texture and display them.

6. The automatic cutting and mapping system for geological mineral map in three-dimensional space according to claim 4 is characterized in that: The calculation module specifically uses the ConvexHull function of Python GDAL to calculate the convex hull of the four corner coordinates in a clockwise order.

7. A computer storage medium, characterized in that: A computer program executable by a processor is stored therein, and the computer program executes the automatic clipping and mapping method of a geological mineral map in three-dimensional space as described in any one of claims 1-3.

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