Map elevation conversion method, device, equipment and program product

Abstract

This disclosure relates to a method, apparatus, device, and program product for map elevation conversion. The method includes: acquiring the absolute elevations of multiple road surface points in a target area, and dividing the target area into multiple grid cells according to a preset grid size; determining the elevation of the low-level center point of each grid cell based on the absolute elevations of each road surface point; performing surface fitting based on the elevations of each low-level center point to generate a low-level elevation reference surface corresponding to the target area; and subtracting the absolute elevations of each road surface point from the elevations of corresponding positions in the low-level elevation reference surface to generate the relative elevations of each initial road surface point. This provides an elevation reference that better fits the local terrain for elevation conversion in the target area, resulting in road surface points that are more closely aligned with the ground after elevation conversion, largely avoiding the abnormal situation of converted ground points floating in the air, thereby improving the accuracy of elevation conversion.

Description

Technical Field

[0001] This disclosure relates to the field of map technology, and in particular to a map elevation conversion method, apparatus, device, and program product. Background Technology

[0002] With the development of electronic map technology, the display and application of 3D maps have emerged. A crucial step in the data processing is converting the absolute elevation / altitude obtained from the data acquisition device into a relative elevation based on the local ground level.

[0003] Currently, the main elevation conversion scheme uses a certain elevation value as the elevation benchmark and subtracts the remaining absolute elevations from this benchmark. However, the relative elevations obtained by this scheme still have some issues that do not perfectly match the ground. Summary of the Invention

[0004] To address the technical problem of low accuracy in elevation conversion results, this disclosure provides a map elevation conversion method, apparatus, equipment, and program product.

[0005] In a first aspect, embodiments of this disclosure provide a map elevation conversion method, including:

[0006] Obtain the absolute elevation of multiple road surface points in the target area, and divide the target area into multiple grid cells according to a preset grid size;

[0007] Based on the absolute elevation of each of the road surface points, determine the elevation of the low-position center point of each of the grid cells;

[0008] Based on the elevation of each of the low-level center points, a surface fitting is performed to generate a low-level elevation reference surface corresponding to the target area.

[0009] The absolute elevation of each road surface point is subtracted from the elevation of the corresponding position in the low-level elevation reference surface to generate the relative elevation of each initial road surface point.

[0010] Secondly, embodiments of this disclosure also provide a map elevation conversion device, comprising:

[0011] The absolute elevation acquisition module is used to acquire the absolute elevation of multiple road surface points in the target area and divide the target area into multiple grid units according to a preset grid size.

[0012] The low-center point elevation determination module is used to determine the low-center point elevation of each grid cell based on the absolute elevation of each of the road surface points.

[0013] The low elevation reference surface generation module is used to perform surface fitting based on the elevation of each of the low elevation center points to generate the low elevation reference surface corresponding to the target area.

[0014] The initial elevation conversion module is used to subtract the absolute elevation of each road surface point from the elevation of the corresponding position in the low-level elevation reference surface to generate the relative elevation of each initial road surface point.

[0015] Thirdly, embodiments of this disclosure also provide an electronic device, including:

[0016] A memory and a processor, wherein the memory is used to store executable instructions of the processor;

[0017] The processor is configured to read the executable instructions from the memory and execute the executable instructions to implement the map elevation conversion method provided in any embodiment of this disclosure.

[0018] Fourthly, embodiments of this disclosure also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the map elevation conversion method provided in any embodiment of this disclosure.

[0019] Fifthly, embodiments of this disclosure also provide a computer program product for executing the map elevation conversion method provided in any embodiment of this disclosure.

[0020] Compared with the prior art, the technical solution provided in this disclosure has at least the following advantages: It converts the absolute elevation of multiple road surface points within the target area into the elevation of the low-level center points of each uniformly distributed grid cell, providing basic data for subsequent surface fitting. Then, it performs surface fitting on the elevations of each low-level center point to obtain a low-level elevation reference surface characterizing the terrain of the target area. Finally, it subtracts the absolute elevation of each road surface point from the low-level elevation reference surface, thus converting the absolute elevation / altitude of the road surface into a relative elevation based on the local ground height of the target area. This provides a more suitable elevation reference for the elevation conversion of the target area, rather than a single elevation value, making the road surface points more closely aligned with the ground after elevation conversion. This largely avoids the abnormal situation of the converted ground points floating in the air, thereby improving the accuracy of the elevation conversion. Attached Figure Description

[0021] The above and other features, advantages, and aspects of the embodiments of this disclosure will become more apparent from the accompanying drawings and the following detailed description. Throughout the drawings, the same or similar reference numerals denote the same or similar elements. It should be understood that the drawings are schematic, and the originals and elements are not necessarily drawn to scale.

[0022] Figure 1 This is a schematic diagram of a road display without elevation conversion provided in an embodiment of this disclosure;

[0023] Figure 2 A schematic flowchart illustrating a map elevation conversion method provided in this embodiment of the disclosure;

[0024] Figure 3 A schematic diagram of a mesh cell division provided in an embodiment of this disclosure;

[0025] Figure 4 A schematic diagram illustrating a process for determining the low-level center point elevation of each grid cell using an erosion algorithm, as provided in an embodiment of this disclosure.

[0026] Figure 5 for Figure 2 The diagram shows the detailed process of S230 in the map elevation transformation method.

[0027] Figure 6 This is a schematic diagram illustrating the result of fitting a low-level elevation datum surface using cubic spline interpolation, as provided in an embodiment of this disclosure.

[0028] Figure 7 A schematic diagram of the elevation distribution of two adjacent map sheets and their eight neighboring regions on the same cross section, provided in an embodiment of this disclosure;

[0029] Figure 8 A flowchart illustrating another map elevation conversion method provided in this embodiment of the disclosure;

[0030] Figure 9 A schematic diagram illustrating the principle of determining a target compression ratio using a high-level elevation reference surface, as provided in this embodiment of the disclosure;

[0031] Figure 10 This is a schematic diagram of the structure of a map elevation conversion device provided in an embodiment of the present disclosure;

[0032] Figure 11 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this disclosure. Detailed Implementation

[0033] Embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings. While some embodiments of this disclosure are shown in the drawings, it should be understood that this disclosure can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of this disclosure. It should be understood that the accompanying drawings and embodiments of this disclosure are for illustrative purposes only and are not intended to limit the scope of protection of this disclosure.

[0034] It should be understood that the steps described in the method embodiments of this disclosure may be performed in different orders and / or in parallel. Furthermore, the method embodiments may include additional steps and / or omit the steps shown. The scope of this disclosure is not limited in this respect.

[0035] The term "comprising" and its variations as used herein are open-ended inclusions, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments". Definitions of other terms will be given in the description below.

[0036] It should be noted that the concepts of "first" and "second" mentioned in this disclosure are used only to distinguish different devices, modules or units, and are not used to limit the order of functions performed by these devices, modules or units or their interdependencies.

[0037] It should be noted that the terms "a" and "a plurality of" used in this disclosure are illustrative rather than restrictive, and those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0038] In 3D map scenarios, data acquisition devices output the absolute elevation / altitude of ground points, while the client-side map display is based on the local ground. If the absolute elevation is directly used for front-end rendering, issues such as... Figure 1 The road 100 shown is floating in the air. Therefore, in order for the front end to display the 3D map correctly, the absolute elevation / altitude of the measured ground points needs to be converted into relative elevations relative to the local ground level.

[0039] The main implementation scheme in related technologies is to divide the high-precision data into blocks and calculate the average elevation value within each data block as the elevation conversion benchmark. Then, the average elevation value is subtracted from each absolute elevation to complete the elevation conversion. However, this scheme uses a single average elevation benchmark across the entire data block, while the actual ground has varying elevations and undulations. This can lead to anomalies where some ground points appear to float in the air or sink into the ground after rendering, resulting in lower accuracy of the elevation conversion.

[0040] Based on the above, this disclosure provides a map elevation conversion method. This method extends the absolute elevation of local road surface points measured in the target area to the elevation of the low-level center points of each grid cell evenly distributed throughout the target area. These low-level center point elevations are then used to fit a low-level elevation reference surface covering the target area. The elevation conversion is completed by subtracting the absolute elevation of each road surface point from the corresponding point in the low-level elevation reference surface. Because this low-level elevation reference surface better conforms to the ground topography of the target area, using it as the reference for elevation conversion can significantly reduce the number of ground points that remain suspended in the air or sunken into the ground after elevation conversion, thereby improving the accuracy of the elevation conversion.

[0041] Figure 2 This is a flowchart illustrating a map elevation conversion method provided in an embodiment of this disclosure. It can be applied to situations where elevation is converted to local relative elevation during 3D map data processing, such as 3D rendering and display of high-precision maps, or fusion of 2D and 3D maps. This map elevation conversion method can be executed by a map elevation conversion device, which can be implemented in software and / or hardware and integrated into an electronic device with a certain computing capability. This electronic device can be, for example, a laptop computer, desktop computer, mobile workstation, or server.

[0042] like Figure 2 As shown, the map elevation conversion method provided in this embodiment may include:

[0043] S210. Obtain the absolute elevation of multiple road surface points in the target area, and divide the target area into multiple grid cells according to the preset grid size.

[0044] The target area refers to the region where elevation conversion is to be performed. This can be a pre-specified area or an area corresponding to a cartographic sheet in map data processing. The absolute elevation of a road surface point refers to the altitude of a point on the road surface, which can be measured using LiDAR sensors, positioning devices, etc.

[0045] The preset mesh size is the size of the pre-defined mesh cells. This preset mesh size can be adjusted according to the actual situation of the target area to determine a more reasonable size. If it is set too large, the subsequently fitted surface will be too flat, making it impossible to simulate some undulating terrain; if it is set too small, it will lead to overfitting.

[0046] For example, the preset grid size is determined based on the length of the interchange deck. The interchange deck length refers to the horizontal projection length from one starting point to the other ending point of the interchange. This length can be determined by statistically analyzing the lengths of multiple interchange decks within the target area, or it can be set empirically. Figure 3As shown, a single grid cell corresponding to the preset grid size can basically cover the length of an overpass deck. This allows for better consideration of the overpass deck elevation during surface construction, resulting in a more accurate fit of the fitted surface to the actual terrain of the target area.

[0047] Specifically, the electronic device can read the absolute elevations of multiple road surface points contained in the target area from the storage medium, or it can read / retrieve the absolute elevations of these multiple road surface points from the elevation data acquisition device. To further improve the accuracy of subsequent elevation conversion, the acquired absolute elevations of each road surface point can be processed by noise reduction or filtering to improve the accuracy of the input data.

[0048] At the same time, such as Figure 3 As shown, the electronic device can divide the target area into uniformly distributed grid units according to a preset grid size.

[0049] S220. Based on the absolute elevation of each road surface point, determine the elevation of the low-position center point of each grid cell.

[0050] The center point elevation refers to the elevation of the center of a grid cell. The low center point elevation refers to the elevation of the center point of a grid cell closer to the ground.

[0051] Specifically, to ensure the smoothness and accuracy of the subsequently fitted surface, elevation data needs to be covered as uniformly as possible within the target area. However, the absolute elevations of the road surface points obtained above are mainly elevation data for the road area, with almost no elevation data in non-road areas. Therefore, considering the need to reduce data acquisition costs and difficulties, and given that the elevation data in non-road areas is primarily used to assist in surface fitting and has relatively low accuracy requirements, this embodiment of the disclosure may not collect elevation data from non-road areas. Instead, it uses the absolute elevations of the road surface points as a basis to perform data expansion and extrapolation on the non-road areas within the target area to obtain the elevation data of each grid cell contained in the target area. The implementation method of this data expansion and extrapolation is not limited; for example, it could be data dilation / erosion in raster data processing, or data interpolation calculations, etc.

[0052] Considering the speed and accuracy of subsequent surface fitting, and that the elevation conversion is based on the local ground height, this embodiment further simplifies the elevation data in each grid cell to a low-center point elevation. This low-center point elevation can be calculated by calculating the statistical values ​​of the absolute elevations of each road surface point contained in the grid cell (such as the minimum, average, median, or the value at a certain percentile of the histogram).

[0053] In some embodiments, a dilation / erosion algorithm for raster data can be used to expand the elevation of each low-level center point in the target area from the absolute elevation of each road surface point. In this embodiment, S220 may include steps A and B.

[0054] Step A: For a data grid cell containing at least one road surface point with an absolute elevation, determine the minimum value among the absolute elevations of all road surface points contained in the data grid cell as the elevation of the low-level center point of the data grid cell.

[0055] Specifically, the electronic device can first determine from all grid cells the grid cells containing at least one absolute elevation of a road surface point (called a data-rich grid cell), such as... Figure 4 The grid cell into which road 410 (shown in bold) falls is the data grid cell 420. Then, the lowest point in each data grid cell—that is, the minimum absolute elevation of all road surface points within the data grid cell—is determined as the low-level center point elevation of the corresponding data grid cell. This ensures that the subsequently fitted low-level surface (also called the ground surface) aligns with the lowest point of the road network data, thus minimizing the possibility of elevation points that are concave with the ground after elevation transformation. It also prevents the upper-level roads of overpasses from being transformed to the ground zero point due to coordinate fitting issues.

[0056] Step B: For dataless grid cells that do not have absolute elevations of road surface points, the elevation of the low-level center point of the dataless grid cell is determined based on the elevation of the low-level center point in the preset adjacent range of the dataless grid cell, according to the erosion algorithm.

[0057] The preset adjacency range is a pre-defined region that is adjacent to the grid cell to be processed, such as 4-adjacency, 8-adjacency, n-adjacency, etc.

[0058] Specifically, the electronic device identifies grid cells from all grid cells that do not contain the absolute elevation of road points (called dataless grid cells), such as... Figure 4 The data includes all grid cells except for the data-filled grid cells 420 shown in the diagram. Then, using an erosion algorithm, the data-filled grid cells with their determined low-level center point elevations are used as the starting grid for data expansion. A preset adjacency range is used as the step size for data expansion to calculate the low-level center point elevations of grid cells without absolute road surface elevations (referred to as data-free grid cells). This eliminates the need to measure the elevation data of the area covered by data-free grid cells, avoiding redundant measurement work, and ensures a uniform distribution of low-level center point elevations within the target area while maintaining the accuracy of the data from the data-filled grid cells.

[0059] In some embodiments, step B includes: traversing each undatated grid cell layer by layer from near to far according to the distance from the data-containing grid cell, and determining the average elevation of each low-level center point in the eight-neighbor range of the traversed undatated grid cell as the low-level center point elevation of the traversed undatated grid cell.

[0060] Specifically, considering that data farther away from the grid cell has less impact, this embodiment sets the preset adjacency range to eight neighborhoods to balance the accuracy and speed of data expansion.

[0061] See Figure 4 Some dataless grid cells are far from data-rich grid cells 420, and they are not adjacent to any of the data-rich grid cells 420 within their eight-neighborhood. Therefore, in this embodiment, a layer-by-layer traversal method is used for data expansion.

[0062] First, the electronic device expands the first-layer no-data grid cell 430, which is closest to the data grid cell 420 and is filled with relatively sparse points. For each first-layer no-data grid cell 430, the existing low-center point elevation in its eight-neighbor range is found, and the average value is calculated. The result is used as the low-center point elevation of the corresponding first-layer no-data grid cell 430.

[0063] Then, the electronic device expands the second-layer dataless grid cell 440, which is closest to the first-layer dataless grid cell 430 and is indicated by cross-grid filling. For each second-layer dataless grid cell 440, the existing low-center elevation in its eight-neighbor range is found, and the average of these elevations is calculated. The result is used as the low-center elevation of the corresponding second-layer dataless grid cell 440.

[0064] Next, the electronic device expands the third-layer dataless grid cell 450, which is closest to the second-layer dataless grid cell 440 and is indicated by more sparse point filling. For each third-layer dataless grid cell 450, the existing low-center elevation in its eight-neighbor range is found, and the average of these elevations is calculated. The result is used as the low-center elevation of the corresponding third-layer dataless grid cell 450.

[0065] Finally, the electronic device extends the fourth-layer dataless grid cell 460, which is shown in white and is closest to the third-layer dataless grid cell 450. For each fourth-layer dataless grid cell 460, the existing low-center elevation within its eight-neighbor range is found, and the average of these elevations is calculated. The result is used as the low-center elevation of the corresponding fourth-layer dataless grid cell 460.

[0066] Through the above processing, we can obtain the following: Figure 3 The elevation of the low center point at the center of each grid cell is shown.

[0067] S230. Based on the elevation of each low-level center point, perform surface fitting to generate the low-level elevation reference surface corresponding to the target area.

[0068] Specifically, electronic devices can perform surface fitting on the elevations of each low-level center point in the target area to obtain simulated ground data for the target area, i.e., a low-level elevation reference surface. Since the elevation of the low-level center point is the lowest point in each grid cell, this low-level elevation reference surface can at least more accurately represent the actual ground topography of the area where the road is located.

[0069] S240. Subtract the absolute elevation of each road surface point from the elevation of the corresponding position in the low elevation reference surface to generate the relative elevation of each initial road surface point.

[0070] Specifically, the electronic device uses a low-level elevation reference surface as the elevation conversion reference (i.e., as the ground 0 point). It calculates the difference between the absolute elevation of each road surface point and the elevation at the corresponding position in the low-level elevation reference surface, thereby converting the absolute elevation of the road surface point into a relative elevation relative to the local ground, i.e., the initial relative elevation of the road surface point.

[0071] In some embodiments, such as Figure 5 As shown, Figure 2 The diagram illustrates the refinement process of S230 in the map elevation transformation method. See also... Figure 5 S230, "Based on the elevation of each low-level center point, perform surface fitting to generate a low-level elevation reference surface corresponding to the target area," includes:

[0072] S531. Obtain the elevation of each low-level center point in the preset adjacent range of the target area.

[0073] Specifically, in the actual processing of map data, there are scenarios where map data is processed in blocks, such as when the target area spans at least two map sheets, or when map data is processed using distributed services. In these situations, if surface fitting is performed in each data block according to the above process, there may be elevation jumps at the edges of the surfaces between data blocks, leading to discontinuous surface stitching or even stitching failure.

[0074] Based on the above, this embodiment also uses the elevation data within the preset adjacent range of the target area as input data for surface fitting data processing. In this way, the electronic device can process and obtain the elevations of each low-level center point within the preset adjacent range of the target area according to the low-level center point elevation processing methods provided in the above embodiments.

[0075] S532. Perform cubic spline interpolation on the elevation of each low-level center point in the target area and the elevation of each low-level center point in the preset adjacent range, and extract the surface corresponding to the target area from the fitted surface as the low-level elevation reference surface.

[0076] Specifically, after the above processing, the electronic device can obtain the elevations of each low-level center point uniformly distributed in the target area and its preset adjacent range. Then, for these low-level center point elevations, cubic spline interpolation curve fitting is performed in the x-axis and y-axis directions respectively, and the curves fitted in the two directions are used to form a surface to obtain the ground surface covering the target area and its preset adjacent range.

[0077] For example, see Figure 6 ,for Figure 1 For the road shown, the electronic equipment can first perform cubic spline interpolation curve fitting using the elevations of the low-level center points along the x-axis to obtain the corresponding, bolded x-axis curve 610. Then, the elevation control points (i.e., the low-level center point elevations) along the y-axis are densified using the x-axis curves 610, and cubic spline interpolation curve fitting is performed on the densified elevation control points to obtain a denser y-axis curve 620, indicated by gray lines. These x-axis curves 610 and y-axis curves 620 together constitute the aforementioned ground surface.

[0078] Next, the electronic device extracts the portion corresponding to the target area from the large-scale ground surface obtained through fitting, using it as the low-level elevation reference surface for the target area. This ensures smooth surface edges between the ground surfaces corresponding to the target area and its surrounding areas, thereby greatly reducing elevation jumps at the junctions of surfaces corresponding to different data blocks, and thus improving the splicing coherence and accuracy between the map data corresponding to different data blocks after elevation transformation.

[0079] For example, when the preset adjacency range is an eight-neighbor range, the processing methods described in the above embodiments can be used to obtain large-scale ground surfaces corresponding to two adjacent map sheets. Then, a curve of a certain cross section can be extracted from one of the map sheets and the ground surface corresponding to its eight-neighbor range as... Figure 7 The first curve 710 shown is used as a curve with the same cross section extracted from the ground surface corresponding to another map sheet and its eight neighboring areas. Figure 7 The second curve 720 is shown. From Figure 7As can be seen, the first curve 710 and the second curve 720 are completely overlapping in their overlapping central area 730, indicating that the low elevation reference surfaces in the two adjacent map sheets are basically overlapping. Therefore, there is almost no elevation jump between the map data after the elevation conversion of these two adjacent map sheets with their low elevation reference surfaces as the ground 0 point, which can improve the smoothness and accuracy of the splicing between adjacent map sheets.

[0080] In some embodiments, it is possible to Figure 2 The map elevation conversion method shown adds a high-level elevation processing step after S240, that is, after S240, it includes: if the relative elevation of the initial road surface point is greater than the preset elevation difference threshold, the relative elevation of the initial road surface point is compressed based on the target compression ratio to generate the relative elevation of the target ground point.

[0081] The preset elevation difference threshold is a pre-set critical value for elevation difference, which can be empirically set based on the actual distribution of roads on the ground. For example, the preset elevation difference threshold is determined based on the height of interchanges. This is because interchanges are the main type of road with elevation differences on the ground, and their overlapping structures are quite complex. Inaccurate 3D display can easily lead users to drive on the wrong road. Therefore, in this embodiment, the preset elevation difference threshold can be determined based on the height of interchanges. For example, the highest height of each interchange in the target area can be determined as the preset elevation difference threshold; alternatively, the heights of many interchanges can be statistically analyzed, and the highest height or the height value at 97% of the height histogram can be determined as the preset elevation difference threshold, such as a six-level interchange with a height of 30m. The target compression ratio is the ratio by which the elevation difference is compressed. It can be a preset ratio value or calculated based on the elevation difference distribution in the target area.

[0082] Specifically, to present users with a 3D map that more closely resembles actual road conditions, the client-side front-end needs to display all roads in the target area according to their actual relative elevations, without omissions. However, in areas with significant elevation differences between roads, such as mountainous regions with large differences between upper and lower roads, the elevation difference remains unchanged after the aforementioned elevation conversion process. This results in lower-level roads being flush with the ground, while upper-level roads, due to their large elevation difference, cannot be rendered and displayed within the visible range.

[0083] Based on the above, this embodiment can compress the relative elevation of roads with excessive elevation differences, based on the initial relative elevation of the ground points determined in the above embodiments, so that they can be displayed in the visible range of the electronic device at a more reasonable scale.

[0084] In practice, since the initial road surface point relative elevation obtained from the above processing is the elevation difference relative to the ground zero point, the electronic device can directly compare the initial road surface point relative elevation with the preset elevation difference threshold. If the initial road surface point relative elevation is less than or equal to the preset elevation difference threshold, it means that the initial road surface point relative elevation has not reached the range of excessive elevation difference, and it can be rendered and displayed normally on the front end, so no further processing is required. If the initial road surface point relative elevation is greater than the preset elevation difference threshold, it means that the road surface point may not be able to be displayed on the front end. Therefore, the electronic device compresses the initial road surface point relative elevation according to its corresponding target compression ratio to obtain the final relative elevation of the ground point, i.e., the target ground point relative elevation.

[0085] In some embodiments, the target compression ratio corresponding to each ground point in the target area can be determined based on the elevation difference distribution within the target area. See also Figure 8 Another elevation conversion process provided in this disclosure includes:

[0086] S801. Obtain the absolute elevation of multiple road surface points in the target area, and divide the target area into multiple grid cells according to the preset grid size.

[0087] S802. Based on the absolute elevation of each road surface point, determine the elevation of the low-position center point of each grid cell.

[0088] S803. Based on the elevation of each low-level center point, perform surface fitting to generate the low-level elevation reference surface corresponding to the target area.

[0089] S804. Subtract the absolute elevation of each road surface point from the elevation of the corresponding position in the low elevation reference surface to generate the relative elevation of each initial road surface point.

[0090] Specifically, see Figure 9 (a) Ground points A and C are above the lower elevation datum surface, while ground points B and D are on the lower elevation datum surface. Therefore, after the subtraction process in this step, the initial relative elevations of ground points B and D can be lowered to the ground zero point position, as shown below. Figure 9 As shown in (b). At the same time, the relative elevations of the corresponding initial road surface points A and C are determined by the elevation differences between AB and CD, respectively.

[0091] S805. Based on the absolute elevation of each road surface point and the preset elevation difference threshold, determine the elevation of the high center point of each grid cell.

[0092] The elevation of the high center point refers to the elevation of the center point of the grid cell that is far from the ground.

[0093] Specifically, in order to improve the compatibility between the target compression ratio and the target area, thereby improving the rationality of subsequent high elevation compression, in this embodiment of the disclosure, a high elevation surface (i.e., a high elevation reference surface) far from the ground can be fitted from the high elevation points of the target area.

[0094] Referring to the descriptions of the above embodiments, in this step, the elevation of the high center point of each grid cell uniformly distributed in the target area can also be obtained from the absolute elevation of each road surface point through data expansion. The calculation method for the high center point elevation of the data grid cell can be to calculate the statistical value of the absolute elevation of each road surface point contained in the grid cell (such as the maximum value or the value at a certain percentile of the histogram).

[0095] In some embodiments, a dilation / erosion algorithm for raster data can be used to expand the elevation of each high-level center point in the target area from the absolute elevation of each road surface point. Specifically, S805 includes: for a data grid cell containing at least one road surface point with an absolute elevation, determining the maximum value among the absolute elevations of each road surface point contained in the data grid cell; if the maximum value is greater than a preset elevation difference threshold, determining the maximum value as the high-level center point elevation of the data grid cell; and if the maximum value is less than or equal to the preset elevation difference threshold, determining the preset elevation difference threshold as the high-level center point elevation of the data grid cell; for a data-free grid cell containing no road surface point absolute elevations, determining the high-level center point elevation of the data-free grid cell based on the high-level center point elevations in a preset adjacent range of the data-free grid cell using an erosion algorithm.

[0096] Specifically, the electronic device can determine the highest point in each data grid cell, that is, the maximum absolute elevation of all road points in the data grid cell. Then, it compares this maximum value with a preset elevation difference threshold. If the maximum value is greater than the preset elevation difference threshold, such as... Figure 9 As shown in (a), ground point A indicates that the elevation difference at this point is too large. Therefore, the maximum value at ground point A is determined as the elevation of the corresponding high-level center point with data grid cells. If the maximum value is less than or equal to the preset elevation difference threshold, such as... Figure 9 As shown in (a), ground point C indicates that its elevation difference is within the displayable range. To improve the accuracy of subsequent target compression ratios and simplify its calculation logic, ground point C can be extended upwards to point M, a position with a preset elevation difference threshold of 30m. The preset elevation difference threshold at point M is then set as the elevation of the corresponding high-level center point with data grid cells. This ensures that the subsequently fitted high-level elevation reference surface can cover all elevation points in the target area, thereby minimizing the possibility of some ground points not being rendered and displayed within the visible range after elevation conversion, and improving the comprehensiveness of the 3D road display.

[0097] Then, the electronic device uses an erosion algorithm, taking the data-rich grid cells with already determined high-level center point elevations as the starting grid for data expansion, and using a preset adjacency range as the step size for data expansion, to calculate the high-level center point elevations of each data-free grid cell. For details of this data expansion process, please refer to the descriptions of the above embodiments.

[0098] S806. Based on the elevation of each high-level center point, perform surface fitting to generate the high-level elevation reference surface corresponding to the target area.

[0099] Specifically, electronic devices can perform surface fitting on the elevation of each high-level center point in the target area, such as by utilizing... Figure 9 (a) The elevations at ground points A and M, etc., are fitted onto a surface to obtain the high-level elevation reference surface of the target area. This high-level elevation reference surface can more comprehensively characterize the distribution of high elevations in the target area, providing more accurate and comprehensive basic data for subsequent calculation of the target compression ratio.

[0100] If processed by S804, the higher elevation datum surface will also change as the lower elevation datum surface is zeroed out. That is, the higher and lower elevation datum surfaces will be subtracted point-by-point to generate... Figure 9 (b) shows the high elevation reference surface. The elevation difference between points on this high elevation reference surface remains constant.

[0101] S807. Based on the elevation of any point in the high-level elevation reference surface and the preset elevation difference threshold, determine the target compression ratio of the corresponding point.

[0102] Specifically, according to the above description, the preset height difference threshold range is within the visible elevation range for rendering. Therefore, in this embodiment, the preset height difference threshold is used as a benchmark to calculate the target compression ratio of each point in the high elevation reference surface.

[0103] For each point on the high-level elevation datum surface, the electronic device calculates the ratio of a preset elevation difference threshold to the point's elevation on the high-level elevation datum surface, using this ratio as the target compression ratio for that point. For example, Figure 9 (b) The elevation of ground point A on the high-level elevation reference surface is 40m, and the preset elevation difference threshold is 30m. Therefore, the target compression ratio for ground point A can be calculated to be 0.75, indicating that the initial relative elevation of ground point A needs to be compressed by 75%. For example, Figure 9 (b) The elevation of ground point C in the high-level elevation datum surface is 30m. Given a preset elevation difference threshold of 30m, the target compression ratio of ground point C can be calculated as 1, representing the initial relative elevation of ground point C without compression. Through this process, the target compression ratio of each point in the high-level elevation datum surface can be obtained.

[0104] S808. Determine whether the relative elevation of the initial road surface point is greater than the preset elevation difference threshold. If yes, proceed to S810; otherwise, proceed to S809.

[0105] S809. Determine the relative elevation of the initial road surface point as the relative elevation of the target ground point.

[0106] Specifically, for Figure 9 (b) As shown in the figure, the ground point C has an initial road surface relative elevation that is less than the preset elevation difference threshold, so it does not need to be compressed. Instead, its initial road surface relative elevation is directly determined as the target ground point relative elevation.

[0107] S810 compresses the relative elevation of the initial road surface points based on the target compression ratio to generate the relative elevation of the target ground points.

[0108] Specifically, for Figure 9 (b) As shown, the initial relative elevation of ground point A is greater than the preset elevation difference threshold. The target compression ratios obtained above can be queried, and the target compression ratio corresponding to ground point A is found to be 0.75. Then, by multiplying the initial relative elevation of ground point A by the target compression ratio, the initial relative elevation of the ground point can be compressed to obtain the target relative elevation of the ground point, making it within the visible range of rendering and display.

[0109] It should be noted that the execution order of S802-S804 and S805-S807 is not limited, and they can be executed in accordance with... Figure 8 The sequential execution shown can be parallel, or it can be an interleaved sequential execution between two sets of steps.

[0110] Figure 10 This is a schematic diagram of a map elevation conversion device provided in an embodiment of this disclosure. Figure 10 As shown, the map elevation conversion device 1000 provided in this embodiment may include:

[0111] The absolute elevation acquisition module 1010 is used to acquire the absolute elevation of multiple road surface points in the target area and divide the target area into multiple grid units according to the preset grid size.

[0112] The low-center point elevation determination module 1020 is used to determine the low-center point elevation of each grid cell based on the absolute elevation of each road surface point.

[0113] The low elevation reference surface generation module 1030 is used to perform surface fitting based on the elevation of each low center point to generate the low elevation reference surface corresponding to the target area.

[0114] The initial elevation conversion module 1040 is used to subtract the absolute elevation of each road surface point from the elevation of the corresponding position in the low-level elevation reference surface to generate the relative elevation of each initial road surface point.

[0115] In some embodiments, the low-center point elevation determination module 1020 includes:

[0116] There is a data grid cell processing submodule, which is used to determine the minimum value among the absolute elevations of all road points contained in a data grid cell that contains at least one road point with absolute elevation as the elevation of the low center point of the data grid cell.

[0117] The dataless grid cell processing submodule is used to determine the low-center elevation of a dataless grid cell based on the low-center elevation of the low-center point in the preset adjacent range of the dataless grid cell, according to the erosion algorithm.

[0118] Furthermore, the data-free grid cell processing submodule is specifically used for:

[0119] Based on the distance from the data grid cells, each undata grid cell is traversed layer by layer from the nearest to the farthest. The average elevation of each low-level center point in the eight-neighbor range of the traversed undata grid cell is determined as the low-level center point elevation of the traversed undata grid cell.

[0120] In some embodiments, the low-level elevation reference surface generation module 1030 is specifically used for:

[0121] Obtain the elevation of each low-level center point within the preset adjacent range of the target area;

[0122] The surface is fitted by cubic spline interpolation of the elevation of each low center point in the target area and the elevation of each low center point in the preset adjacent range. The surface corresponding to the target area is extracted from the fitted surface and used as the low elevation reference surface.

[0123] In some embodiments, the map elevation conversion device 1000 further includes a target ground point relative elevation generation module, used for:

[0124] After subtracting the absolute elevation of each road surface point from the elevation of the corresponding position in the low elevation reference surface to generate the relative elevation of each initial road surface point, if the relative elevation of the initial road surface point is greater than the preset elevation difference threshold, the relative elevation of the initial road surface point is compressed based on the target compression ratio to generate the relative elevation of the target ground point.

[0125] In some embodiments, the map elevation conversion device 1000 further includes a target compression ratio determination module, used for:

[0126] If the relative elevation of the initial road surface point is greater than the preset elevation difference threshold, the relative elevation of the initial road surface point is compressed based on the target compression ratio. Before generating the relative elevation of the target ground point, the elevation of the high center point of each grid cell is determined based on the absolute elevation of each road surface point and the preset elevation difference threshold.

[0127] Based on the elevation of each high-level center point, a surface fitting is performed to generate a high-level elevation reference surface corresponding to the target area.

[0128] Based on the elevation of any point in the high-level elevation reference surface and the preset elevation difference threshold, the target compression ratio of the corresponding point is determined.

[0129] Furthermore, the target compression ratio determination module is specifically used for:

[0130] For a data grid cell containing at least one road surface point with an absolute elevation, determine the maximum value among the absolute elevations of all road surface points contained in the data grid cell. When the maximum value is greater than a preset elevation difference threshold, the maximum value is determined as the elevation of the high center point of the data grid cell. When the maximum value is less than or equal to the preset elevation difference threshold, the preset elevation difference threshold is determined as the elevation of the high center point of the data grid cell.

[0131] For dataless grid cells that do not contain absolute elevations of road surface points, the elevation of the high-level center point of the dataless grid cell is determined based on the elevation of the high-level center point in the preset adjacent range of the dataless grid cell, according to the erosion algorithm.

[0132] In some embodiments, the preset grid size is determined based on the length of the overpass deck, and the preset elevation difference threshold is determined based on the height of the overpass.

[0133] The map elevation conversion device provided in this disclosure can execute the map elevation conversion method provided in any embodiment of this disclosure, and has the corresponding functional modules and beneficial effects of the method. Content not described in detail in the device embodiments of this disclosure can be referred to the description in any method embodiment of this disclosure.

[0134] Figure 11 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present disclosure. It is used to exemplarily illustrate an electronic device that implements the map elevation conversion method in any embodiment of the present disclosure and should not be construed as a specific limitation on the embodiments of the present disclosure.

[0135] like Figure 11As shown, electronic device 1100 may include a processor (e.g., central processing unit, graphics processor, etc.) 1101, which can perform various appropriate actions and processes according to a program stored in read-only memory (ROM) 1102 or a program loaded from storage device 1108 into random access memory (RAM) 1103. RAM 1103 also stores various programs and data required for the operation of electronic device 1100. Processor 1101, ROM 1102, and RAM 1103 are interconnected via bus 1104. Input / output (I / O) interface 1105 is also connected to bus 1104.

[0136] Typically, the following devices can be connected to I / O interface 1105: input devices 1106 including, for example, touchscreens, touchpads, keyboards, mice, cameras, microphones, accelerometers, gyroscopes, etc.; output devices 1107 including, for example, liquid crystal displays (LCDs), speakers, vibrators, etc.; storage devices 1108 including, for example, magnetic tapes, hard disks, etc.; and communication devices 1109. Communication device 1109 allows electronic device 1100 to communicate wirelessly or wiredly with other devices to exchange data. Although an electronic device 1100 with various devices is shown, it should be understood that it is not required to implement or possess all of the devices shown. More or fewer devices may be implemented or possessed alternatively.

[0137] In particular, according to embodiments of this disclosure, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of this disclosure include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication device 1109, or installed from storage device 1108, or installed from ROM 1102. When the computer program is executed by processor 1101, it can perform the functions defined in the map elevation conversion method provided in any embodiment of this disclosure.

[0138] It should be noted that the computer-readable medium described in this disclosure can be a computer-readable signal medium or a computer-readable storage medium, or any combination thereof. A computer-readable storage medium can be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any combination thereof. More specific examples of a computer-readable storage medium may include, but are not limited to: an electrical connection having one or more wires, a portable computer disk, a hard disk, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage device, magnetic storage device, or any suitable combination thereof. In this disclosure, a computer-readable storage medium can be any tangible medium containing or storing a program that can be used by or in conjunction with an instruction execution system, apparatus, or device. In this disclosure, a computer-readable signal medium can include a data signal propagated in baseband or as part of a carrier wave, carrying computer-readable program code. Such propagated data signals can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination thereof. A computer-readable signal medium can be any computer-readable medium other than a computer-readable storage medium, which can send, propagate, or transmit a program for use by or in connection with an instruction execution system, apparatus, or device. The program code contained on the computer-readable medium can be transmitted using any suitable medium, including but not limited to: wires, optical fibers, RF (radio frequency), etc., or any suitable combination thereof.

[0139] In some implementations, the client and server can communicate using any currently known or future-developed network protocol such as HTTP (Hypertext Transfer Protocol), and can interconnect with digital data communication (e.g., communication networks) of any form or medium. Examples of communication networks include local area networks (“LANs”), wide area networks (“WANs”), the Internet (e.g., the Internet of Things), and peer-to-peer networks (e.g., ad hoc peer-to-peer networks), as well as any currently known or future-developed networks.

[0140] The aforementioned computer-readable medium may be included in the aforementioned electronic device; or it may exist independently and not assembled into the electronic device.

[0141] The aforementioned computer-readable medium carries one or more programs, which, when executed by the electronic device, cause the electronic device to perform the map elevation conversion method provided in any embodiment of this disclosure.

[0142] In embodiments of this disclosure, computer program code for performing the operations of this disclosure can be written in one or more programming languages ​​or a combination thereof. These programming languages ​​include, but are not limited to, object-oriented programming languages ​​such as Java, Smalltalk, and C++, as well as conventional procedural programming languages ​​such as the "C" language or similar programming languages. The program code can be executed entirely on a computer, partially on a computer, as a standalone software package, partially on a computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving remote computers, the remote computer can be connected to the computer via any type of network, including a local area network (LAN) or a wide area network (WAN), or it can be connected to an external computer (e.g., via the Internet using an Internet service provider).

[0143] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flowcharts, and combinations of blocks in the block diagrams and / or flowcharts, can be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0144] The modules described in the embodiments of this disclosure can be implemented in software or hardware. The names of the modules are not, in some cases, intended to limit the functionality of the module itself.

[0145] The functions described above in this document can be performed, at least in part, by one or more hardware logic components. For example, exemplary types of hardware logic components that can be used, without limitation, include: Field Programmable Gate Arrays (FPGAs), Application-Specific Integrated Circuits (ASICs), Application Standard Products (ASSPs), System-on-Chip (SoCs), Complex Programmable Logic Devices (CPLDs), and so on.

[0146] In the context of this disclosure, a computer-readable medium can be a tangible medium that may contain or store a program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable medium can be a computer-readable signal medium or a computer-readable storage medium. A computer-readable medium can be, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of computer-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fiber, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination of the foregoing.

[0147] The above description is merely a preferred embodiment of this disclosure and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of this disclosure is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the above-described concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features disclosed in this disclosure that have similar functions.

[0148] Furthermore, while the operations are described in a specific order, this should not be construed as requiring these operations to be performed in the specific order shown or in a sequential order. In certain environments, multitasking and parallel processing may be advantageous. Similarly, while several specific implementation details are included in the above discussion, these should not be construed as limiting the scope of this disclosure. Certain features described in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, various features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments.

[0149] Although the subject matter has been described using language specific to structural features and / or methodological logic, it should be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or actions described above. Rather, the specific features and actions described above are merely illustrative examples of implementing the claims.

Claims

1. A map elevation conversion method, characterized in that, include: Obtain the absolute elevation of multiple road surface points in the target area, and divide the target area into multiple grid cells according to a preset grid size; Based on the absolute elevation of each of the road surface points, determine the elevation of the low-position center point of each of the grid cells; Based on the elevation of each of the low-level center points, a surface fitting is performed to generate a low-level elevation reference surface corresponding to the target area. The absolute elevation of each road surface point is subtracted from the elevation of the corresponding position in the low elevation reference surface to generate the relative elevation of each initial road surface point. If the relative elevation of the initial road surface point is greater than the preset elevation difference threshold, the relative elevation of the initial road surface point is compressed based on the target compression ratio to generate the relative elevation of the target ground point.

2. The method according to claim 1, wherein, Determining the elevation of the low-level center point of each grid cell based on the absolute elevation of each of the road surface points includes: For a data grid cell containing at least one of the absolute elevations of the road surface points, the minimum value among the absolute elevations of the road surface points contained in the data grid cell is determined as the elevation of the low-level center point of the data grid cell. For a dataless grid cell that does not contain the absolute elevation of the road surface point, the elevation of the low-position center point of the dataless grid cell is determined based on the elevation of the low-position center point in the preset adjacent range of the dataless grid cell according to the erosion algorithm.

3. The method according to claim 2, wherein, For dataless grid cells where the absolute elevation of the road surface point is not present, the determination of the low-level center point elevation of the dataless grid cell based on the low-level center point elevation within a preset adjacent range, according to the erosion algorithm, includes: The data-free grid cells are traversed layer by layer from the nearest to the farthest data-containing grid cells, and the average elevation of the low-level center point in the eight-neighbor range of the traversed data-free grid cell is determined as the low-level center point elevation of the traversed data-free grid cell.

4. The method according to any one of claims 1 to 3, wherein, The step of performing surface fitting based on the elevation of each of the low-level center points to generate the low-level elevation reference surface corresponding to the target region includes: Obtain the elevation of each low-level center point within the preset adjacent range of the target area; A cubic spline interpolation surface fitting is performed on the elevations of each low-level center point in the target area and the elevations of each low-level center point in the preset adjacent range, and the surface corresponding to the target area is extracted from the fitted surface as the low-level elevation reference surface.

5. The method according to claim 1, wherein, Before compressing the relative elevation of the initial road surface point based on the target compression ratio to generate the relative elevation of the target ground point if the relative elevation of the initial road surface point is greater than a preset elevation difference threshold, the method further includes: Based on the absolute elevation of each road surface point and the preset elevation difference threshold, the elevation of the high center point of each grid cell is determined; Based on the elevation of each of the high-level center points, a surface fitting is performed to generate a high-level elevation reference surface corresponding to the target area. Based on the elevation of any point in the high-level elevation reference surface and the preset elevation difference threshold, the target compression ratio of the corresponding point is determined.

6. The method according to claim 5, wherein, The process of determining the elevation of the high-level center point of each grid cell based on the absolute elevation of each road surface point and the preset elevation difference threshold includes: For a data grid cell containing at least one of the road surface points with absolute elevation, the maximum value among the absolute elevations of the road surface points contained in the data grid cell is determined. When the maximum value is greater than the preset elevation difference threshold, the maximum value is determined as the elevation of the high-level center point of the data grid cell. When the maximum value is less than or equal to the preset elevation difference threshold, the preset elevation difference threshold is determined as the elevation of the high-level center point of the data grid cell. For a dataless grid cell where the absolute elevation of the road surface point is not present, the elevation of the high-level center point of the dataless grid cell is determined based on the elevation of the high-level center point within the preset adjacent range of the dataless grid cell, according to the erosion algorithm.

7. The method according to claim 1, wherein, The preset grid size is determined based on the length of the overpass deck, and the preset height difference threshold is determined based on the height of the overpass.

8. A map elevation conversion device, characterized in that, include: The absolute elevation acquisition module is used to acquire the absolute elevation of multiple road surface points in the target area and divide the target area into multiple grid units according to a preset grid size. The low-center point elevation determination module is used to determine the low-center point elevation of each grid cell based on the absolute elevation of each of the road surface points. The low elevation reference surface generation module is used to perform surface fitting based on the elevation of each of the low elevation center points to generate the low elevation reference surface corresponding to the target area. The initial elevation conversion module is used to subtract the absolute elevation of each road surface point from the elevation of the corresponding position in the low elevation reference surface to generate the relative elevation of each initial road surface point; if the relative elevation of the initial road surface point is greater than a preset elevation difference threshold, the relative elevation of the initial road surface point is compressed based on the target compression ratio to generate the relative elevation of the target ground point.

9. An electronic device, characterized in that, include: A memory and a processor, wherein the memory is used to store executable instructions of the processor; The processor is configured to read the executable instructions from the memory and execute the executable instructions to implement the map elevation conversion method as described in any one of claims 1 to 7.

10. A computer program product, characterized in that, The computer program product is used to execute the map elevation conversion method according to any one of claims 1 to 7.

Images