A method and system for processing urban and rural building surveying and mapping maps based on a mobile GIS platform

Abstract

The present invention relates to a method for processing urban and rural building surveying and mapping maps of a mobile GIS platform, comprising: performing different semantic segmentation on an original map image according to supported zoom levels, calculating texture entropy of each segmented area, obtaining all segmented areas whose texture entropy of the segmented area is less than a preset value, and obtaining a rectangle with a maximum area in each segmented area, wherein the rectangular area adopts a grid tile containing all elements; dividing the remaining part of the map into a plurality of rectangles, wherein the rectangular area adopts a mixed tile, determining the level of an element layer in the mixed tile based on texture entropy, and determining the elements in the element layer of the mixed tile by adopting the level; when using a mobile GIS platform to survey and map urban and rural buildings, determining a tile rendering order according to line of sight information, and when rendering to the mixed tile, determining the elements and the detail level of the elements when rendering the element layer of the mixed tile according to the line of sight information and resource utilization of the mobile GIS platform.

Description

Technical Field

[0001] The present invention relates to the field of surveying and mapping, and in particular to a method and system for processing urban and rural building surveying and mapping maps on a mobile GIS platform. Background Art

[0002] Urban and rural building surveying is an indispensable part of planning, infrastructure construction, real estate management, post-disaster assessment and other fields. Traditional building surveying methods usually rely on ground measurement, manual drawing or aerial photogrammetry, but there are problems such as high cost, long cycle, and limited accuracy, which makes it difficult to meet the increasingly complex surveying needs. Building surveying based on geographic information system (GIS) technology can effectively process and analyze spatial information, and provide efficient and accurate data support for building surveying. However, existing GIS platforms often focus on data processing and application in fixed places, lack the ability to adapt to dynamic environments and mobile operations, and have certain limitations in the surveying and mapping of urban and rural buildings. Mobile GIS platforms can realize real-time data collection, processing and sharing, greatly improving the efficiency and accuracy of building surveying.

[0003] Map tiles are the foundation of mobile GIS platforms. By dividing large maps into small pieces and adopting optimization strategies, the rendering and display efficiency of maps is effectively improved. Map tiles are divided into vector tiles and raster tiles. Raster tiles are already rendered images, and the mobile GIS platform only needs to display them. However, at high zoom levels, the amount of data will increase dramatically, and the style cannot be modified dynamically. Vector tiles store the geometric information and attribute information of geographic features. They store vector data, which is much smaller than raster tiles. They can be redrawn when zooming without jagged or blurring. However, rendering requires the CPU and memory resources of the mobile GIS platform. If the style rules are too complex or there are too many map features, the client rendering performance may be reduced and jamming may occur. Summary of the invention

[0004] In order to improve the rendering effect and loading speed of maps in urban and rural building surveying and mapping on a mobile GIS platform, the present invention provides a method for processing urban and rural building surveying and mapping maps on a mobile GIS platform, the method comprising the following steps:

[0005] Perform different semantic segmentation on the original map image according to the supported zoom levels, calculate the texture entropy of each segmented area, obtain all segmented areas whose texture entropy is less than a preset value, and obtain the rectangle with the largest area in each segmented area, wherein the rectangular area adopts a grid tile containing all elements;

[0006] Divide the remaining part of the map into a plurality of rectangles, wherein the rectangular area adopts hybrid tiles, determines the level of the element layer in the hybrid tiles based on texture entropy, and adopts the level to determine the elements in the element layer of the hybrid tiles; the hybrid tiles at least include a base layer and an element layer, wherein the base layer adopts raster tiles and the element layer adopts vector tiles;

[0007] When using a mobile GIS platform to survey and map urban and rural buildings, the tile rendering order is determined based on line of sight information. When rendering mixed tiles, the elements and detail levels of the element layers when rendering the mixed tiles are determined based on the line of sight information and resource utilization of the mobile GIS platform.

[0008] Preferably, the determining the level of the element layer in the mixed tile based on the texture entropy and using the level to determine the elements in the element layer of the mixed tile are specifically:

[0009] Get the preset texture entropy interval, each texture entropy interval corresponds to a feature level;

[0010] Determine the texture entropy interval where the texture entropy is located, and then determine the element level corresponding to the texture entropy;

[0011] The features in the feature layer that are lower than the determined feature level are added to the base layer of the mixed tile and the raster tile is regenerated; the features in the feature layer that are not lower than the determined feature level are taken as the features of the feature layer.

[0012] Preferably, determining the tile rendering order according to the line of sight information is specifically as follows:

[0013] Determine the viewpoint based on the user's current position or the camera's position, and use the viewpoint to generate a frustum, generating a bounding box for each tile;

[0014] Calculate the distance from the center of the tile where the tile's bounding box and the viewing frustum intersect to the viewpoint;

[0015] The tiles are sorted according to the distance to obtain a tile rendering order.

[0016] Preferably, determining the elements and detail levels of the elements when rendering the element layer of the hybrid tile according to the line of sight information and the resource utilization of the mobile GIS platform is specifically:

[0017] Determine the obscured elements using the sight line information, and remove the obscured elements from the element layer;

[0018] Calculate the distance from each element in the element layer of the hybrid tile to the viewpoint, determine the priority of element rendering based on the distance, calculate the weighted value using the resource utilization of the mobile GIS platform, and use the weighted value to weight the complexity and distance of the element to determine the detail level of the element.

[0019] Preferably, the step of using the weighted value to weight the complexity and distance of the element to determine the detail level of the element is specifically as follows:

[0020] Calculate the weighted sum of the normalized complexity and the normalized distance to obtain the feature value;

[0021] The weighted value and the feature value of the element are used to calculate the element detail level score, and the detail level of the element is determined according to the element detail level score.

[0022] On the other hand, the present invention provides a system for urban and rural building surveying and mapping processing on a mobile GIS platform, the system comprising the following modules:

[0023] A map segmentation module is used to perform different semantic segmentations on the original map image according to the supported zoom levels, calculate the texture entropy of each segmented area, obtain all segmented areas whose texture entropy is less than a preset value, and obtain the rectangle with the largest area in each segmented area, wherein the rectangular area adopts a grid tile containing all elements;

[0024] A map tile determination module, used to divide the remaining part of the map into a plurality of rectangles, wherein the rectangular area adopts mixed tiles, determines the level of the element layer in the mixed tiles based on texture entropy, and adopts the level to determine the elements in the element layer of the mixed tiles; the mixed tiles at least include a base layer and an element layer, wherein the base layer adopts raster tiles and the element layer adopts vector tiles;

[0025] The rendering module is used to determine the tile rendering order according to the line of sight information when mapping urban and rural buildings using the mobile GIS platform. When rendering to mixed tiles, the elements and the detail level of the elements when rendering the element layer of the mixed tiles are determined according to the line of sight information and the resource utilization of the mobile GIS platform.

[0026] Preferably, the determining the level of the element layer in the mixed tile based on the texture entropy and using the level to determine the elements in the element layer of the mixed tile are specifically:

[0027] Get the preset texture entropy interval, each texture entropy interval corresponds to a feature level;

[0028] Determine the texture entropy interval where the texture entropy is located, and then determine the element level corresponding to the texture entropy;

[0029] The features in the feature layer that are lower than the determined feature level are added to the base layer of the mixed tile and the raster tile is regenerated; the features in the feature layer that are not lower than the determined feature level are taken as the features of the feature layer.

[0030] Preferably, determining the tile rendering order according to the line of sight information is specifically as follows:

[0031] Determine the viewpoint based on the user's current position or the camera's position, and use the viewpoint to generate a frustum, generating a bounding box for each tile;

[0032] Calculate the distance from the center of the tile where the tile's bounding box and the viewing frustum intersect to the viewpoint;

[0033] The tiles are sorted according to the distance to obtain a tile rendering order.

[0034] Preferably, determining the elements and detail levels of the elements when rendering the element layer of the hybrid tile according to the line of sight information and the resource utilization of the mobile GIS platform is specifically:

[0035] Determine the obscured elements using the sight line information, and remove the obscured elements from the element layer;

[0036] Calculate the distance from each element in the element layer of the hybrid tile to the viewpoint, determine the priority of element rendering based on the distance, calculate the weighted value using the resource utilization of the mobile GIS platform, and use the weighted value to weight the complexity and distance of the element to determine the detail level of the element.

[0037] Preferably, the step of using the weighted value to weight the complexity and distance of the element to determine the detail level of the element is specifically as follows:

[0038] Calculate the weighted sum of the normalized complexity and the normalized distance to obtain the feature value;

[0039] The weighted value and the feature value of the element are used to calculate the element detail level score, and the detail level of the element is determined according to the element detail level score.

[0040] In addition, the present invention also provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the method described above is implemented.

[0041] For areas with simple textures and little change, the present invention uses raster tiles containing all elements for storage and transmission, thereby reducing the amount of data and improving the loading speed. For areas with complex textures and densely distributed elements, hybrid tiles are used, that is, the base layer uses raster tiles and the element layer uses vector tiles. Hybrid tiles retain the scalability, clarity and advantages of easy editing and analysis of vector data, while avoiding the problems of excessive data volume and low rendering efficiency caused by the use of all vector tiles. Moreover, the detail level of the elements is dynamically adjusted according to the resource utilization of the mobile GIS platform, the complexity of the elements, and the distance from the viewpoint. When the device performance is good and the resources are sufficient, a more sophisticated element model can be displayed to provide a better visual effect; when the device performance is poor and the resources are tight, a lower-precision model can be selected to ensure the smoothness of the rendering. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a flow chart of Embodiment 1;

[0043] Figure 2 A schematic diagram of a grid tile and a hybrid tile;

[0044] Figure 3 This is a structural diagram of the second embodiment. DETAILED DESCRIPTION

[0045] In this article, relational terms such as first and second, etc. are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In a first embodiment of the present invention, Figure 1As shown, the present invention provides a method for processing urban and rural building surveying and mapping maps on a mobile GIS platform, the method comprising the following steps:

[0048] S1, performing different semantic segmentation on the original map image according to the supported zoom levels, calculating the texture entropy of each segmented area, obtaining all segmented areas whose texture entropy is less than a preset value, and obtaining the rectangle with the largest area in each segmented area, wherein the rectangular area adopts a grid tile containing all elements;

[0049] In a map, the zoom level is the display scale of the map. Generally speaking, a smaller zoom level displays a larger map area with less details, while a larger zoom level displays a smaller area with more details. In a map display, it is displayed through tiles, and the tiles at different zoom levels are different. Semantic segmentation is performed on the original map image at each zoom level. In a map image, semantic segmentation can divide the image into building areas, road areas, water areas, vegetation areas, and so on. Different semantic segmentations are required for different zoom levels. For example, at a smaller zoom level, it may only be necessary to distinguish between large plots of land and water areas, while at a larger zoom level, the outline of each building needs to be segmented more finely. At different zoom ratios, the original map image is also different. In a mobile GIS platform, the map zoom operation will be performed, and the results of semantic segmentation are different at different zoom ratios.

[0050] In image processing, the higher the texture entropy, the more complex and irregular the texture of the image; the lower the texture entropy, the simpler and more regular the texture of the image. If the texture entropy of a segmented area is low, the corresponding compression rate is also high due to the large number of identical pixels. If the texture entropy of a segmented area is small, raster tiles are used because the compression rate is high and the network resources and storage resources of the mobile GIS platform are low. Raster tiles are images composed of pixels, each of which represents a color value. For simple areas with small texture entropy, raster tiles are used for storage and display. The amount of information in simple areas is relatively small, and the use of raster tiles can effectively reduce the amount of data and rendering overhead. In one embodiment, since semantic segmentation may be irregular in shape, in order to make the shape regular, for each segmented area with a texture entropy less than a preset value, find the rectangle with the largest area in the segmented area, and use raster tiles for the rectangular area. Since a square is a special case of a rectangle, the rectangle described here includes a square. In another embodiment, the specific calculation process of texture entropy is to calculate the gray level co-occurrence matrix (GLCM) of the segmented area, then normalize the gray level co-occurrence matrix, calculate the entropy of the normalized gray level co-occurrence matrix, and use the entropy of the gray level co-occurrence matrix as the texture entropy. In another embodiment, the texture entropy is obtained by graying the rectangle, retaining the texture of the rectangle, and then calculating the entropy value.

[0051] S2, dividing the remaining part of the map into a plurality of rectangles, wherein the rectangular area adopts hybrid tiles, determining the level of the element layer in the hybrid tiles based on texture entropy, and determining the elements in the element layer of the hybrid tiles by adopting the level; the hybrid tiles at least include a base layer and an element layer, wherein the base layer adopts raster tiles and the element layer adopts vector tiles;

[0052] After the rectangle using raster tiles is determined, the rest of the map is divided into multiple rectangles, and the rectangles of the rest of the map use hybrid tiles. Hybrid tiles are a type of map tile that combines raster tiles and vector tiles, and are composed of at least two layers: a raster base layer and one or more vector feature layers. The higher the texture entropy, the more complex and dense the map features in the area are, so the assigned feature layer level should also be higher in order to contain more detailed feature information. Conversely, in areas with lower texture entropy, the feature layer level is also lower, and it only needs to contain relatively simple feature information. For example, in an area with high texture entropy (such as the city center), the feature layer may contain the precise outline and attribute information of each building; while in an area with low texture entropy (such as the suburbs), the feature layer may only contain the centerline information of the road. After the feature layer level is determined, the specific features that the hybrid tile needs to contain are determined according to the level. Among them, the feature is equivalent to an object on the map. Each object has at least spatial location and attribute information. A house, a tree, or a road can be a feature. The rendered features and feature details are different for different feature layer levels.

[0053] In one embodiment, the determining the level of the element layer in the mixed tile based on the texture entropy and using the level to determine the elements in the element layer of the mixed tile are specifically:

[0054] Get the preset texture entropy interval, each texture entropy interval corresponds to a feature level;

[0055] Determine the texture entropy interval where the texture entropy is located, and then determine the element level corresponding to the texture entropy;

[0056] The features in the feature layer that are lower than the determined feature level are added to the base layer of the mixed tile and the raster tile is regenerated; the features in the feature layer that are not lower than the determined feature level are taken as the features of the feature layer.

[0057] The value range of texture entropy is divided into several intervals in advance. For example, the value range of texture entropy can be divided into three intervals: [0-0.3), [0.3-0.6), [0.6-1], and each texture entropy interval corresponds to an element level. For example, the above three intervals can correspond to element levels 1, 2, and 3 respectively, and the higher the level, the more detailed and important the element is. The texture entropy of each rectangle in step S2 is calculated to determine the texture entropy interval it falls into, thereby determining the element level corresponding to the rectangle. If the texture entropy value calculated for a rectangle is 0.45, it falls within the interval [0.3-0.6), so the element level of the rectangle is determined to be 2. Elements below the determined element level are relatively unimportant or not detailed enough, and will be sunk to the base layer (i.e., the raster base layer), and raster tiles will be regenerated, thereby reducing the data volume of vector tiles and improving rendering efficiency. Elements not lower than the determined element level are relatively important or detailed enough and will be retained in the element layer (i.e., the vector element layer). For example, the feature level of a rectangle in step S2 is 2. The feature layer contains the following features: Level 1 features: main roads, landmark buildings; Level 2 features: secondary roads, small buildings; Level 3 features: detailed outlines of buildings, POI information. Level 1 features (main roads, landmark buildings) will be sunk to the base layer and the raster base map will be regenerated. Level 2 and level 3 features (secondary roads, small buildings, detailed outlines of buildings, POI information) will be retained in the vector feature layer. Rendering vector data usually consumes more resources than rendering raster data. By converting unimportant features into raster data, the number of features that need to be rendered vector can be reduced, thereby increasing the rendering speed. The regeneration of raster tiles is usually completed in the map data preprocessing stage, rather than in the real-time rendering process when users browse the map, and will not affect users of the mobile GIS platform. Figure 2 A schematic diagram showing raster tiles and hybrid tiles at one zoom level is shown.

[0058] S3, when using the mobile GIS platform to survey and map urban and rural buildings, the tile rendering order is determined according to the line of sight information. When rendering to the mixed tile, the elements and the detail level of the elements when rendering the element layer of the mixed tile are determined according to the line of sight information and the resource utilization of the mobile GIS platform.

[0059] When using a mobile GIS platform for urban and rural building mapping, the tile rendering order is determined based on the line of sight information, and the areas that users are most concerned about are displayed first, so as to improve the map loading speed and user experience, and avoid the jamming caused by loading all tiles at once. In one embodiment, the center area of ​​the map on the screen is used as the line of sight information, for example, the coordinates of the center point of the screen in the map are (100, 200) or the longitude and latitude are (73, 116). The tile rendering order is determined based on the distance between the center of the tile and the center point of the map on the screen. The farther the distance, the later the rendering order.

[0060] In another embodiment, determining the tile rendering order according to the line of sight information is specifically as follows:

[0061] Determine the viewpoint based on the user's current position or the camera's position, and use the viewpoint to generate a frustum, generating a bounding box for each tile;

[0062] Calculate the distance from the center of the tile where the tile's bounding box and the viewing frustum intersect to the viewpoint;

[0063] The tiles are sorted according to the distance to obtain a tile rendering order.

[0064] The viewpoint is the position where the user observes the scene, that is, the position of the user's eyes or camera. The three-dimensional space area within the user's field of view constitutes a viewing cone, and only objects within the viewing cone will be rendered on the screen. In map tile rendering, each tile can be represented by a bounding box to represent the geographical area it covers. Determine whether the bounding box of each tile intersects with the viewing cone. If there is no intersection, it means that the tile is not within the user's field of view and does not need to be rendered. It is directly culled, thereby greatly reducing the amount of rendering. For tiles whose bounding boxes intersect with the viewing cone, calculate the distance from the center point of the bounding box to the viewpoint. Sort the tiles according to the calculated distance, usually from near to far, that is, the tiles closer to the viewpoint are rendered first.

[0065] For the raster tiles in step S1, since they are tiles in picture format, rendering is relatively simple, but for the hybrid tiles, since they involve the element layer, rendering is relatively time-consuming and requires more resources. In one embodiment, the elements blocked by the hybrid tiles are determined according to the line of sight information, and the blocked elements are removed and not rendered. For the remaining elements of the hybrid tiles, the elements to be rendered are determined according to the resource utilization of the mobile GIS platform. If the resource utilization rate of the mobile GIS platform is low and the resources are relatively sufficient, all the elements of the hybrid tiles are rendered. If the resource utilization rate of the mobile GIS platform is high and the resources are insufficient, the elements with lower levels are rendered.

[0066] In order to display all elements of the hybrid tile, in another embodiment, the elements and detail levels of the elements when rendering the element layer of the hybrid tile are determined according to the line of sight information and the resource utilization of the mobile GIS platform, specifically:

[0067] Determine the obscured elements using the sight line information, and remove the obscured elements from the element layer;

[0068] Calculate the distance from each element in the element layer of the hybrid tile to the viewpoint, determine the priority of element rendering based on the distance, calculate the weighted value using the resource utilization of the mobile GIS platform, and use the weighted value to weight the complexity and distance of the element to determine the detail level of the element.

[0069] Use line of sight information such as the view frustum to perform occlusion culling. If an element is completely obscured by other elements, it does not contribute to the final rendering result, so it can be removed from the rendering list to reduce rendering overhead. Calculate the distance from the remaining, or unobstructed, elements to the viewpoint, and use a rendering order from near to far, that is, the closer the element is to the viewpoint, the higher the rendering priority, and the earlier it is rendered. Dynamically adjust the weighting value based on the current resource utilization. For example, when resources are tight, select a low level of detail (LOD) model. Specifically, calculate the complexity of the element and the distance from the element to the viewpoint, where the complexity of the element represents the level of detail of the element. There are many ways to calculate the complexity of the element, including but not limited to the number of attribute fields of the element, or the number of vertices or faces of the element.

[0070] In one embodiment, the weighted value is used to weight the complexity and distance of the element to determine the detail level of the element, specifically:

[0071] Calculate the weighted sum of the normalized complexity and the normalized distance to obtain the feature value;

[0072] The weighted value and the feature value of the element are used to calculate the element detail level score, and the detail level of the element is determined according to the element detail level score.

[0073] Since the complexity and distance of features usually have different dimensions and orders of magnitude, directly performing weighted summation may result in unreasonable weights. Therefore, they need to be normalized first and their values ​​scaled to a common range. Use the preset weights to multiply the normalized complexity and distance respectively, and then add the results to obtain a comprehensive feature feature value. Then, the feature level of detail score is calculated using the weighted value and the feature feature value. The higher the current resource utilization rate, the farther from the viewpoint, the higher the complexity, the higher the level of detail score, and the higher the level of detail used; the higher the level of detail, the lower the accuracy of the feature. According to the calculated feature level of detail score, select a suitable LOD model. For example, the score can be divided into several intervals, each of which corresponds to an LOD level. Assuming there are three LOD levels: LOD1 is a high-precision model, LOD2 is a medium-precision model, and LOD3 is a low-precision model. The feature level of detail score is also divided into three levels, with level 1 being the lowest and level 3 being the highest. It corresponds to the above three LOD levels one by one. When the level of detail score of an element is level 3, it corresponds to LOD3.

[0074] In a second embodiment of the present invention, Figure 3 As shown, the present invention provides a system for urban and rural building surveying and mapping processing on a mobile GIS platform, and the system includes the following modules:

[0075] A map segmentation module is used to perform different semantic segmentations on the original map image according to the supported zoom levels, calculate the texture entropy of each segmented area, obtain all segmented areas whose texture entropy is less than a preset value, and obtain the rectangle with the largest area in each segmented area, wherein the rectangular area adopts a grid tile containing all elements;

[0076] A map tile determination module, used to divide the remaining part of the map into a plurality of rectangles, wherein the rectangular area adopts mixed tiles, determines the level of the element layer in the mixed tiles based on texture entropy, and adopts the level to determine the elements in the element layer of the mixed tiles; the mixed tiles at least include a base layer and an element layer, wherein the base layer adopts raster tiles and the element layer adopts vector tiles;

[0077] The rendering module is used to determine the tile rendering order according to the line of sight information when mapping urban and rural buildings using the mobile GIS platform. When rendering to mixed tiles, the elements and the detail level of the elements when rendering the element layer of the mixed tiles are determined according to the line of sight information and the resource utilization of the mobile GIS platform.

[0078] Preferably, the determining the level of the element layer in the mixed tile based on the texture entropy and using the level to determine the elements in the element layer of the mixed tile are specifically:

[0079] Get the preset texture entropy interval, each texture entropy interval corresponds to a feature level;

[0080] Determine the texture entropy interval where the texture entropy is located, and then determine the element level corresponding to the texture entropy;

[0081] The features in the feature layer that are lower than the determined feature level are added to the base layer of the mixed tile and the raster tile is regenerated; the features in the feature layer that are not lower than the determined feature level are taken as the features of the feature layer.

[0082] Preferably, determining the tile rendering order according to the line of sight information is specifically as follows:

[0083] Determine the viewpoint based on the user's current position or the camera's position, and use the viewpoint to generate a frustum, generating a bounding box for each tile;

[0084] Calculate the distance from the center of the tile where the tile's bounding box and the viewing frustum intersect to the viewpoint;

[0085] The tiles are sorted according to the distance to obtain a tile rendering order.

[0086] Preferably, determining the elements and detail levels of the elements when rendering the element layer of the hybrid tile according to the line of sight information and the resource utilization of the mobile GIS platform is specifically:

[0087] Determine the obscured elements using the sight line information, and remove the obscured elements from the element layer;

[0088] Calculate the distance from each element in the element layer of the hybrid tile to the viewpoint, determine the priority of element rendering based on the distance, calculate the weighted value using the resource utilization of the mobile GIS platform, and use the weighted value to weight the complexity and distance of the element to determine the detail level of the element.

[0089] Preferably, the step of using the weighted value to weight the complexity and distance of the element to determine the detail level of the element is specifically as follows:

[0090] Calculate the weighted sum of the normalized complexity and the normalized distance to obtain the feature value;

[0091] The weighted value and the feature value of the element are used to calculate the element detail level score, and the detail level of the element is determined according to the element detail level score.

[0092] In a third embodiment of the present invention, the present invention further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the method described in the first embodiment is implemented.

[0093] In a fourth embodiment of the present invention, the present invention further provides a computer device, which includes at least a memory and a processor, wherein a computer program is stored in the memory, and when the computer program is executed by the processor, the method described in the first embodiment is implemented.

[0094] Through the description of the above implementation methods, technicians in this field can clearly understand that each implementation method can be implemented by adding a necessary general hardware platform, and of course can also be implemented by combining hardware and software. Based on this understanding, the above technical solution is essentially or the part that contributes to the prior art can be embodied in the form of a computer product, and the present invention can be in the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it, and other embodiments may also be used. Although the present invention has been described in detail with reference to the aforementioned embodiments, ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for processing urban and rural building surveying and mapping on a mobile GIS platform, characterized in that: The method comprises the following steps: Perform different semantic segmentation on the original map image according to the supported zoom levels, calculate the texture entropy of each segmented area, obtain all segmented areas whose texture entropy is less than a preset value, and obtain the rectangle with the largest area in each segmented area, wherein the rectangular area adopts a grid tile containing all elements; Divide the remaining part of the map into a plurality of rectangles, wherein the rectangular area adopts hybrid tiles, determines the level of the element layer in the hybrid tiles based on texture entropy, and adopts the level to determine the elements in the element layer of the hybrid tiles; the hybrid tiles at least include a base layer and an element layer, wherein the base layer adopts raster tiles and the element layer adopts vector tiles; When using a mobile GIS platform to survey and map urban and rural buildings, the tile rendering order is determined based on line of sight information. When rendering mixed tiles, the elements and detail levels of the element layers when rendering the mixed tiles are determined based on the line of sight information and resource utilization of the mobile GIS platform.

2. The method according to claim 1, characterized in that The step of determining the level of the element layer in the mixed tile based on the texture entropy and using the level to determine the elements in the element layer of the mixed tile is specifically as follows: Get the preset texture entropy interval, each texture entropy interval corresponds to a feature level; Determine the texture entropy interval where the texture entropy is located, and then determine the element level corresponding to the texture entropy; The features in the feature layer that are lower than the determined feature level are added to the base layer of the mixed tile and the raster tile is regenerated; the features in the feature layer that are not lower than the determined feature level are taken as the features of the feature layer.

3. The method according to claim 1, characterized in that The tile rendering order is determined according to the line of sight information, specifically: Determine the viewpoint based on the user's current position or the camera's position, and use the viewpoint to generate a frustum, generating a bounding box for each tile; Calculate the distance from the center of the tile where the bounding box of the tile and the view frustum intersect to the viewpoint; The tiles are sorted according to the distance to obtain a tile rendering order.

4. The method according to claim 1, characterized in that The determining of the elements and the detail level of the elements when rendering the element layer of the hybrid tile according to the sight line information and the resource utilization of the mobile GIS platform is specifically: Determine the obscured elements using the sight line information, and remove the obscured elements from the element layer; Calculate the distance from each element in the element layer of the hybrid tile to the viewpoint, determine the priority of element rendering based on the distance, calculate the weighted value using the resource utilization of the mobile GIS platform, and use the weighted value to weight the complexity and distance of the element to determine the detail level of the element.

5. The method according to claim 4, characterized in that The method of using the weighted value to weight the complexity and distance of the element to determine the detail level of the element is specifically as follows: Calculate the weighted sum of the normalized complexity and the normalized distance to obtain the feature value; The weighted value and the feature value of the element are used to calculate the element detail level score, and the detail level of the element is determined according to the element detail level score.

6. A mobile GIS platform urban and rural building surveying and mapping system, characterized in that: The system includes the following modules: A map segmentation module is used to perform different semantic segmentations on the original map image according to the supported zoom levels, calculate the texture entropy of each segmented area, obtain all segmented areas whose texture entropy is less than a preset value, and obtain the rectangle with the largest area in each segmented area, wherein the rectangular area adopts a grid tile containing all elements; A map tile determination module, used to divide the remaining part of the map into a plurality of rectangles, wherein the rectangular area adopts mixed tiles, determines the level of the element layer in the mixed tiles based on texture entropy, and adopts the level to determine the elements in the element layer of the mixed tiles; the mixed tiles at least include a base layer and an element layer, wherein the base layer adopts raster tiles and the element layer adopts vector tiles; The rendering module is used to determine the tile rendering order according to the line of sight information when mapping urban and rural buildings using the mobile GIS platform. When rendering to mixed tiles, the elements and the detail level of the elements when rendering the element layer of the mixed tiles are determined according to the line of sight information and the resource utilization of the mobile GIS platform.

7. The system according to claim 6, characterized in that The step of determining the level of the element layer in the mixed tile based on the texture entropy and using the level to determine the elements in the element layer of the mixed tile is specifically as follows: Get the preset texture entropy interval, each texture entropy interval corresponds to a feature level; Determine the texture entropy interval where the texture entropy is located, and then determine the element level corresponding to the texture entropy; The features in the feature layer that are lower than the determined feature level are added to the base layer of the mixed tile and the raster tile is regenerated; the features in the feature layer that are not lower than the determined feature level are taken as the features of the feature layer.

8. The system according to claim 6, characterized in that The tile rendering order is determined according to the line of sight information, specifically: Determine the viewpoint based on the user's current position or the camera's position, and use the viewpoint to generate a frustum, generating a bounding box for each tile; Calculate the distance from the center of the tile where the bounding box of the tile and the view frustum intersect to the viewpoint; The tiles are sorted according to the distance to obtain a tile rendering order.

9. The system according to claim 6, characterized in that The determining of the elements and the detail level of the elements when rendering the element layer of the hybrid tile according to the sight line information and the resource utilization of the mobile GIS platform is specifically: Determine the obscured elements using the sight line information, and remove the obscured elements from the element layer; Calculate the distance from each element in the element layer of the hybrid tile to the viewpoint, determine the priority of element rendering based on the distance, calculate the weighted value using the resource utilization of the mobile GIS platform, and use the weighted value to weight the complexity and distance of the element to determine the detail level of the element.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the computer program implements the method according to any one of claims 1 to 5.

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