Method and device for acquiring geographic coordinate values of contour of interest surface from online map

Abstract

The invention belongs to the technical field of geographic information data processing, and relates to a method and a device for acquiring geographic coordinate values of a contour of an interest surface from an online map. The method comprises the following steps: acquiring original grids and pixel resolution of a surface of interest from map data, determining at least one target road corresponding to the surface of interest from the map data, generating a buffer area corresponding to the target road, generating a middle grid set corresponding to the surface of interest, segmenting a target grid set from the middle grid set, and obtaining a boundary contour line corresponding to the interest surface, and calculating a geographic coordinate value corresponding to the boundary contour line. The method can solve the problems of inconvenient acquisition, data missing and low real-time performance when the coordinate data of the plane of interest is acquired in an online map, and meets the requirements of high-precision geographic information processing and analysis.

Description

Technical Field

[0001] The technical field to which the present invention belongs is the field of geographic information data processing, and relates to a method and device for obtaining the geographic coordinate values of the contour of an area of interest from an online map. Background Art

[0002] In the field of geographic information data processing technology, the existing methods for obtaining the coordinates of an area of interest (AOI) from an online map mainly include two categories: map service API calls and open-source data extraction. Specifically as follows: The first method uses the API call interface provided by the map service to extract the boundary data of the AOI area of interest. However, this method depends on the data source of the service provider, requires additional API call interfaces and data processing operations, and has poor adaptability to the boundary of the area of interest with complex shapes, and cannot meet the requirements of high-precision geographic information analysis.

[0003] The second method is to extract through foreign open-source map data. This type of method requires manual data stitching, and the data accuracy depends on community contributions, and there are problems of data missing or lagging updates.

[0004] It can be seen that although these technologies have achieved the collection and processing of geographic data through different paths, they are limited by multiple factors such as data sources, coordinate systems, performance, and compliance, and there are obvious technical bottlenecks. Therefore, it is urgent to solve the problems existing in the prior art when obtaining the coordinate data of the area of interest from the online map, such as inconvenient acquisition, data missing, and low real-time performance, which make it difficult to meet the requirements of high-precision geographic information processing and analysis. Summary of the Invention

[0005] An embodiment of the present invention provides a method for obtaining the geographic coordinate values of the contour of an area of interest from an online map, which is used to solve the related problems in the prior art. The method includes: Obtaining the original raster and pixel resolution of the area of interest from the map data; Based on the position of the point of interest in the area of interest, determining at least one target road corresponding to the area of interest from the map data, and generating a buffer area corresponding to the target road; Generating an intermediate raster set corresponding to the area of interest based on the original raster and the buffer area; Dividing a target raster set from the intermediate raster set based on the corresponding relationship between the original pixel value of the area of interest and a preset value; Obtaining a boundary contour line corresponding to the area of interest based on the target raster set; Based on the coordinate values of the pixel points in the area of interest, the pixel resolution, the geographic coordinate values corresponding to each point of interest in the area of interest, and the offset of the pixel in the geographic coordinate system, calculate the geographic coordinate values corresponding to the boundary contour line.

[0006] Specifically, the obtaining the original raster and pixel resolution of the area of interest from the map data includes: From the map data, according to the name of the area of interest, obtain the coordinate values of all points of interest corresponding to this area of interest; Use the raster containing the coordinate values of all points of interest as the original raster, and obtain the pixel resolution corresponding to the original raster.

[0007] Specifically, the determining at least one target road corresponding to the area of interest from the map data based on the location of the points of interest in the area of interest includes: Calculate the Euclidean distance from each point of interest to each road in the map, and use the road with the calculated result less than the distance threshold as the target road.

[0008] Specifically, the generating a buffer area corresponding to the target road includes: Calculate the vector data of the target road, and project and convert the vector data into the coordinate system consistent with the original raster; According to the coordinate values of the target road, generate a buffer area with a preset width around the target road.

[0009] Specifically, the generating a set of intermediate rasters corresponding to the area of interest based on the original raster and the buffer area includes: Perform spatial overlay clipping on the original raster and the buffer area to generate a set of sub-raster blocks containing road segmentation information; Convert the gray values of the raster blocks to be processed in the set of sub-raster blocks to obtain the set of intermediate rasters.

[0010] Specifically, the splitting out a set of target rasters from the set of intermediate rasters based on the corresponding relationship between the original pixel values of the area of interest and a preset value includes: In the set of intermediate rasters, update the pixel values greater than or equal to the first preset threshold of the original raster pixels to 0; update the pixel values less than the first preset threshold of the original raster pixels to 255 to obtain the first raster set; Traverse the first raster set using the first preset window. When all pixel values within the area covered by the first preset window are 0, retain the pixel value corresponding to the center position of the first preset window as 0, otherwise update it to 255 to obtain the second raster set; Traverse the second grid set using a second preset window. When there is a 0 in the pixel values within the area covered by the second preset window, update the pixel value corresponding to the center position of the second preset window to 0 to obtain the target grid set.

[0011] Specifically, obtaining the boundary contour line corresponding to the region of interest based on the target grid set includes: Perform Gaussian filtering on the target grid set and calculate the gradient vector value; According to a preset maximum threshold and minimum threshold, perform non-maximum suppression and double-threshold detection on the processed target grid set to obtain the boundary contour line corresponding to the region of interest.

[0012] Specifically, after obtaining the boundary contour line and before calculating the geographical coordinate values corresponding to the boundary contour line, it further includes: Smooth the boundary contour line, retain the inflection point coordinate values of the region of interest, and obtain the vector data set of the boundary contour line; Calculating the geographical coordinate values corresponding to the boundary contour line based on the pixel point coordinate values in the region of interest, the pixel resolution, the geographical coordinate values corresponding to each point of interest in the region of interest, and the offset of the pixel in the geographical coordinate system includes: Calculate the geographical coordinate values corresponding to the boundary contour line according to the pixel point coordinate values, pixel resolution, and offset of each point in the vector data set.

[0013] Specifically, the calculation formula for calculating the geographical coordinate values corresponding to the boundary contour line according to the pixel point coordinate values, pixel resolution, and offset of each point in the vector data set includes:

[0014] Where is the pixel coordinates of each point in the vector data set, is the geographical coordinate of each point in the vector data set, and are the offsets of the pixel in the geographical coordinate system respectively, is the pixel resolution.

[0015] An embodiment of the present invention further provides a device for obtaining the geographical coordinate values of the contour of a region of interest from an online map. The device includes: A first acquisition unit for acquiring the original grid of the region of interest and the pixel resolution from the map data; A first generation unit, configured to determine at least one target road corresponding to the area of interest from the map data based on the location of the point of interest in the area of interest, and generate a buffer area corresponding to the target road; A second generation unit, configured to generate an intermediate grid set corresponding to the area of interest based on the original grid and the buffer area; A segmentation unit, configured to segment a target grid set from the intermediate grid set based on the correspondence between the original pixel value of the area of interest and a preset value; A second acquisition unit, configured to obtain a boundary contour line corresponding to the area of interest based on the target grid set; A calculation unit, configured to calculate the geographical coordinate value corresponding to the boundary contour line based on the pixel point coordinate value in the area of interest, the pixel resolution, the geographical coordinate value corresponding to each point of interest in the area of interest, and the offset of the pixel in the geographical coordinate system.

[0016] A method for obtaining the geographical coordinate value of the contour of the area of interest from an online map provided by an embodiment of the present invention. The method is based on the original grid, the pixel resolution, and relevant information in the road, and can finally calculate the geographical coordinate value corresponding to the boundary contour line. It can solve the problems of inconvenient acquisition, data loss, and low real-time performance in obtaining the coordinate data of the area of interest in the online map, and meet the requirements of high-precision geographical information processing and analysis. Description of the Drawings

[0017] Figure 1 A flowchart of a method for obtaining the geographical coordinate value of the contour of the area of interest from an online map provided by an embodiment of the present invention; Figure 2 A structural diagram of a device for obtaining the geographical coordinate value of the contour of the area of interest from an online map provided by an embodiment of the present invention. Detailed Embodiments

[0018] To make the above objects, features, and advantages of the present application more obvious and understandable, the following detailed description of the specific embodiments of the present application is provided in conjunction with the accompanying drawings. Many specific details are set forth in the following description to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present application. Therefore, the present application is not limited by the specific embodiments disclosed below.

[0019] In the description of the present application, it should be understood that if there are terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., the orientation or positional relationship indicated by these terms is based on the orientation or positional relationship shown in the drawings. These are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present application.

[0020] In addition, if there are terms such as "first" and "second", these terms are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present application, if there is a term "plurality", the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise specifically defined.

[0021] An embodiment of the present invention provides a method for obtaining the geographical coordinate values of the profile of an area of interest from an online map, as Figure 1 shown. Specifically, this method includes: Step 11: Obtain the original raster and pixel resolution of the area of interest from the map data. Specifically, this step includes: From the map data, according to the name of the area of interest, obtain the coordinate values of all points of interest (POIs) corresponding to this area of interest.

[0022] Use the raster containing the coordinate values of all points of interest as the original raster, and obtain the pixel resolution corresponding to the original raster. This step can be retrieved through the AOI name in the online map service, and the original raster and pixel resolution including the complete AOI range can be obtained by taking a screenshot.

[0023] Step 12: Based on the positions of the points of interest in the area of interest, determine at least one target road corresponding to the area of interest from the map data, and generate a buffer area corresponding to this target road. The specific process includes: Calculate the Euclidean distance from each point of interest to each road in the map, and use the road with the calculated result less than the distance threshold as the target road.

[0024] Calculate the vector data of the target road, and project and convert the vector data into the coordinate system consistent with the original raster. Generate a buffer area with a preset width around the target road according to the coordinate values of the target road. The value of the preset width can be determined according to the road grade.

[0025] Step 13, generate an intermediate raster set corresponding to the region of interest based on the original raster and the buffer area; this step specifically includes: Perform spatial overlay clipping on the original raster and the buffer area to generate a set of sub-raster blocks containing road segmentation information; According to the following formula (1), convert the raster blocks to be processed in the set of sub-raster blocks into grayscale rasters , obtain a grayscale raster set, and use this grayscale raster set as the intermediate raster set; Formula (1); where R, G, and B are the grayscale values of the three color channels in the three primary colors respectively; , , are weight coefficients respectively, and the weight coefficients can be set according to the actual situation.

[0026] Step 14, segment a target raster set from the intermediate raster set based on the correspondence between the original pixel values of the region of interest and a preset value; specifically include:

[0027] In the intermediate raster set, update the pixel values greater than or equal to the first preset threshold to = 0; update the pixel values less than the first preset threshold to = 255, to obtain a first raster set ; as shown in formula (2).

[0028] Formula (2); Traverse the first raster set according to the first preset window size . When all the pixel values within the coverage area of the first preset window are 0, retain the pixel value at the corresponding position of the center of the first preset window as 0, otherwise update it to 255, to obtain a second raster set .

[0029] Traverse the second raster set according to the second preset window size. When there is a 0 among the pixel values within the coverage area of this second preset window, update the pixel value at the corresponding position of the center of the second preset window to 0, to obtain the target raster set 。

[0030] Step 15: Obtain the boundary contour line corresponding to the area of interest based on the target grid set. Specifically, this step includes: Perform Gaussian filtering on the target grid set with a filter kernel size of 5*5, and calculate the gradient vector values; According to a preset maximum threshold and minimum threshold , perform non-maximum suppression and double-threshold detection on the processed target grid set to obtain the edge information corresponding to the area of interest , and form a boundary contour line.

[0031] Step 16: Smooth the boundary contour line using the Douglas-Peucker algorithm, retain the inflection point coordinate values of the contour of the area of interest, and obtain the vector data set of each point P on the boundary contour line ; is the pixel coordinate of point P on the boundary.

[0032] Step 17: Calculate the geographic coordinate values corresponding to the boundary contour line based on the pixel coordinate values in the area of interest, the pixel resolution, the geographic coordinate values corresponding to each point of interest in the area of interest, and the offset of the pixel in the geographic coordinate system. Specifically as follows: The geographic coordinate values corresponding to the boundary contour line can be calculated according to the pixel coordinate values, pixel resolution, and offset of each point in the vector data set. Specifically, traverse point P in the vector data set in sequence, and convert the pixel coordinates to geographic coordinates according to the following formula (3) to obtain the geographic coordinates of the vector boundary of the AOI boundary contour line: Formula (3); where is the pixel coordinate of point P, is the geographic coordinate of point P, and are the offsets of the pixel in the geographic coordinate system respectively, is the pixel resolution.

[0033] A method for obtaining the geographic coordinate values of the contour of an area of interest from an online map provided by an embodiment of the present invention is based on the original raster, pixel resolution, and relevant information in the road, and can finally calculate the geographic coordinate values corresponding to the boundary contour line. It can solve the problems of inconvenient acquisition, data missing, and low real-time performance when obtaining the coordinate data of the area of interest in the online map, and meet the requirements of high-precision geographic information processing and analysis.

[0034] Such as Figure 2As shown in the figure, an embodiment of the present invention provides a device for obtaining the geographical coordinate values of the contour of an area of interest from an online map. The device includes: A first acquisition unit 21, configured to acquire the original raster and the pixel resolution of the area of interest from the map data; A first generation unit 22, configured to determine at least one target road corresponding to the area of interest from the map data based on the positions of the points of interest in the area of interest, and generate a buffer area corresponding to the target road; A second generation unit 23, configured to generate an intermediate raster set corresponding to the area of interest based on the original raster and the buffer area; A segmentation unit 24, configured to segment a target raster set from the intermediate raster set based on the correspondence between the original pixel values of the area of interest and a preset value; A second acquisition unit 25, configured to obtain a boundary contour line corresponding to the area of interest based on the target raster set; A calculation unit 26, configured to calculate the geographical coordinate values corresponding to the boundary contour line based on the pixel point coordinate values in the area of interest, the pixel resolution, the geographical coordinate values corresponding to each point of interest in the area of interest, and the offset of the pixel in the geographical coordinate system.

[0035] The first acquisition unit 21 is specifically configured to, from the map data, according to the name of the area of interest, acquire the coordinate values of all points of interest corresponding to the area of interest; use the raster containing the coordinate values of all points of interest as the original raster, and acquire the pixel resolution corresponding to the original raster.

[0036] The first generation unit 22 is specifically configured to calculate the Euclidean distance from each point of interest to each road in the map, and use the road with the calculation result less than the distance threshold as the target road.

[0037] The second generation unit 23 is specifically configured to calculate the vector data of the target road, and project and convert the vector data into a coordinate system consistent with the original raster; generate a buffer area with a preset width around the target road according to the coordinate values of the target road.

[0038] The second generation unit 23 is specifically configured to perform spatial overlay and clipping on the original raster and the buffer area to generate a set of sub-raster blocks containing road segmentation information; perform gray value conversion on the to-be-processed raster blocks in the set of sub-raster blocks to obtain the intermediate raster set.

[0039] The splitting unit 24 is specifically configured to update the pixel values of the pixels in the intermediate grid set whose original grid pixel values are greater than or equal to the first preset threshold to 0; update the pixel values of the pixels whose original grid pixel values are less than the first preset threshold to 255 to obtain a first grid set; traverse the first grid set according to the first preset window size, and when all the pixel values within the area covered by the first preset window are 0, keep the pixel value at the corresponding position of the center of the first preset window as 0, otherwise update it to 255 to obtain a second grid set; traverse the second grid set according to the second preset window size, and when there is a 0 in the pixel values within the area covered by the second preset window, update the pixel value at the corresponding position of the center of the second preset window to 0 to obtain the target grid set.

[0040] The second obtaining unit 25 is specifically configured to perform Gaussian filtering on the target grid set and calculate the gradient vector value; perform non-maximum suppression and double-threshold detection on the processed target grid set according to the preset maximum threshold and minimum threshold to obtain the boundary contour line corresponding to the interest surface.

[0041] The device further includes a third obtaining unit 27, configured to smooth the boundary contour line and retain the inflection point coordinate values of the interest surface to obtain a vector data set of the boundary contour line; The calculation unit 26 is specifically configured to calculate the geographical coordinate values corresponding to the boundary contour line according to the pixel point coordinate values, pixel resolution, and offset of each point in the vector data set.

[0042] An embodiment of the present invention provides an electronic device, where the electronic device includes a processor, a memory, and a program or instruction stored on the memory and executable on the processor, and the program or instruction is executed by the processor to perform the steps of the above method for obtaining the geographical coordinate values of the interest surface contour from an online map.

[0043] The present invention aims to efficiently and accurately obtain the AOI vector boundary coordinates from an online map by combining geographic information processing and image analysis technologies. Specifically, first, query the corresponding POI point coordinates according to the AOI name, and obtain the raster image with the complete AOI range and its pixel resolution from the online map service. At the same time, read and convert the road vector data into the coordinate system consistent with the raster image. Then, use the buffer analysis method to generate a road buffer and perform spatial overlay clipping with the raster image to form an accurate division of the AOI range. Next, convert the raster to a grayscale image by the weighting method, and perform threshold processing and sliding window operations to extract the preliminary boundary information of the AOI. Then, through Gaussian filtering for denoising, gradient calculation, and edge detection, obtain the accurate edge information of the AOI, and track the boundary pixels clockwise to form a complete contour line. Finally, use the Douglas-Peucker algorithm to smooth the contour line and retain the key inflection points, and convert the pixel coordinates into geographic coordinates to achieve the efficient and accurate acquisition of the AOI vector boundary coordinates, effectively solving the inaccurate problem existing in the prior art when obtaining AOI coordinates from an online map, and improving the accuracy and reliability of geographic information processing and analysis.

[0044] In this application, unless otherwise clearly specified and defined, if terms such as "installation", "connection", "connection", "fixation", etc. appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the connection inside two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0045] In this application, unless otherwise clearly specified and defined, if a description such as the first feature being "on" or "under" the second feature appears, its meaning can be that the first and second features are in direct contact, or the first and second features are indirectly in contact through an intermediate medium. Moreover, the first feature being "above", "over", and "on" the second feature can be that the first feature is directly above or obliquely above the second feature, or simply means that the first feature has a higher horizontal height than the second feature. The first feature being "under", "below", and "beneath" the second feature can be that the first feature is directly below or obliquely below the second feature, or simply means that the first feature has a lower horizontal height than the second feature.

[0046] It should be noted that if an element is referred to as "fixed to" or "disposed on" another element, it can be directly on the other element or there may be an intermediate element. If an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intermediate element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are only for the purpose of illustration and do not represent the only implementation. The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0047] The above-described embodiments only represent several implementation manners of the present application. The description is relatively specific and detailed, but it should not be understood as a limitation to the scope of the patent application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the appended claims.

Claims

1. A method for obtaining the geographical coordinate values of the outline of an area of interest from an online map, characterized in that, The method includes: Obtaining the original raster and pixel resolution of the area of interest from map data; Based on the positions of the points of interest in the area of interest, determining at least one target road corresponding to the area of interest from the map data, and generating a buffer area corresponding to the target road; Generating an intermediate raster set corresponding to the area of interest based on the original raster and the buffer area; Segmenting a target raster set from the intermediate raster set based on the correspondence between the original pixel values of the area of interest and a preset value; Obtaining a boundary contour line corresponding to the area of interest based on the target raster set; Calculating the geographic coordinate values corresponding to the boundary contour line based on the pixel coordinate values in the area of interest, the pixel resolution, the geographic coordinate values corresponding to each point of interest in the area of interest, and the offset of the pixel in the geographic coordinate system.

2. The method according to claim 1, characterized in that The obtaining the original raster and pixel resolution of the area of interest from map data includes: From the map data, according to the name of the area of interest, obtaining the coordinate values of all points of interest corresponding to the area of interest; Taking the raster containing the coordinate values of all points of interest as the original raster, and obtaining the pixel resolution corresponding to the original raster.

3. The method according to claim 1, wherein The determining at least one target road corresponding to the area of interest from the map data based on the positions of the points of interest in the area of interest includes: Calculating the Euclidean distance from each point of interest to each road in the map, and taking the road with the calculation result less than the distance threshold as the target road.

4. The method according to claim 1, wherein The generating a buffer area corresponding to the target road includes: Calculating the vector data of the target road, and projecting and converting the vector data into a coordinate system consistent with the original raster; Generating a buffer area with a preset width around the target road according to the coordinate values of the target road.

5. The method according to claim 1, wherein The generating an intermediate raster set corresponding to the area of interest based on the original raster and the buffer area includes: Performing spatial overlay clipping on the original raster and the buffer area to generate a set of sub-raster blocks containing road segmentation information; Converting the gray values of the to-be-processed raster blocks in the set of sub-raster blocks to obtain the intermediate raster set.

6. The method according to claim 1, characterized in that The segmenting a target raster set from the intermediate raster set based on the correspondence between the original pixel values of the area of interest and a preset value includes: Updating the pixel values in the intermediate raster set that are greater than or equal to the first preset threshold to 0; updating the pixel values less than the first preset threshold to 255 to obtain a first raster set; Traversing the first raster set using a first preset window. When all pixel values within the area covered by the first preset window are 0, retaining the pixel value corresponding to the center position of the first preset window as 0, otherwise updating it to 255 to obtain a second raster set; Traversing the second raster set using a second preset window. When there is a 0 among the pixel values within the area covered by the second preset window, updating the pixel value corresponding to the center position of the second preset window to 0 to obtain the target raster set.

7. The method according to claim 1, wherein The obtaining of the boundary contour line corresponding to the region of interest based on the target grid set includes: Performing Gaussian filtering on the target grid set and calculating gradient vector values; Performing non-maximum suppression and double-threshold detection on the processed target grid set according to a preset maximum threshold and minimum threshold to obtain the boundary contour line corresponding to the region of interest.

8. The method according to claim 1, characterized in that, After obtaining the boundary contour line and before calculating the geographical coordinate values corresponding to the boundary contour line, it further includes: Smoothing the boundary contour line, retaining the inflection point coordinate values of the region of interest, and obtaining a vector data set of the boundary contour line; The calculating of the geographical coordinate values corresponding to the boundary contour line based on the pixel point coordinate values in the region of interest, the pixel resolution, the geographical coordinate values corresponding to each interest point in the region of interest, and the offset of the pixel in the geographical coordinate system includes: Calculating the geographical coordinate values corresponding to the boundary contour line according to the pixel point coordinate values, pixel resolution, and offset of each point in the vector data set.

9. The method according to claim 8, wherein The calculation formula for calculating the geographical coordinate values corresponding to the boundary contour line according to the pixel point coordinate values, pixel resolution, and offset of each point in the vector data set includes: ; where is the pixel coordinates of each point in the vector data set, is the geographic coordinates of each point in the vector data set, and are the offsets of the pixel in the geographic coordinate system respectively, is the pixel resolution.

10. An apparatus for obtaining the geographical coordinate values of the outline of an area of interest from an online map, characterized in that, The device includes: A first obtaining unit, configured to obtain the original grid of the region of interest and the pixel resolution from map data; A first generating unit, configured to determine at least one target road corresponding to the region of interest from the map data based on the position of the interest point in the region of interest, and generate a buffer region corresponding to the target road; A second generating unit, configured to generate an intermediate grid set corresponding to the region of interest based on the original grid and the buffer region; A segmentation unit, configured to segment out a target grid set from the intermediate grid set based on the corresponding relationship between the original pixel values of the region of interest and a preset value; A second obtaining unit, configured to obtain the boundary contour line corresponding to the region of interest based on the target grid set; A calculating unit, configured to calculate the geographical coordinate values corresponding to the boundary contour line based on the pixel point coordinate values in the region of interest, the pixel resolution, the geographical coordinate values corresponding to each interest point in the region of interest, and the offset of the pixel in the geographical coordinate system.

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