A terrain three-dimensional evolution simulation system and method for long channel

Abstract

The application provides a terrain three-dimensional evolution simulation system and method for long navigation channel, the system comprises a CPU end and a GPU end; the CPU end extracts GeoTiff files from a database and maps them into R16 texture objects in response to a plurality of water channels and two survey times; determines intersecting tiles intersecting with the water channels in a three-dimensional scene, calculates texture mapping coordinates and local modeling coordinates thereof; calculates interpolation coefficients based on a current simulation progress value and a survey time code in response to a dynamic evolution instruction; the GPU end samples the plurality of water channels according to the texture mapping coordinates in a vertex shader stage to obtain two survey time elevation values, linearly interpolates the elevation values based on the interpolation coefficients to obtain a current frame terrain elevation, updates terrain grid vertex elevations according to the local modeling coordinates and converts the terrain grid vertex elevations into CGCS2000 coordinates; and performs dynamic thematic coloring according to the terrain elevations in a fragment shader stage. The application realizes efficient continuous three-dimensional evolution dynamic simulation of long navigation channel terrain.

Description

Technical Field

[0001] This invention relates to the field of intelligent waterway technology, specifically to a three-dimensional terrain evolution simulation system and method for long waterways. Background Technology

[0002] In the construction and operation of smart waterways, monitoring and simulating changes in the underwater topography of river channels is a core task for ensuring navigation safety and guiding channel maintenance. Waterway management departments typically conduct regular underwater topographic surveys to obtain topographic data from different periods and assess the scouring and silting status of the waterway by comparing and analyzing topographic changes from different surveys. With the development of 3D visualization technology, waterway topography visualization based on 3D simulation engines has become an important technical means.

[0003] Currently, in the field of 3D visualization and evolution analysis of underwater topography in waterways, there are two main technical solutions: First, the discretization display method based on thematic maps: This method generates thematic images from underwater topographic elevation data from different measurements and performs discretized 3D visualization. However, this method can only display the static topographic state of a single measurement and cannot show the continuous change process of the topography. Even by switching between topographic models from different measurements to simulate evolution, only abrupt, discrete switching can be achieved, failing to achieve a smooth, continuous evolution effect. Second, the evolution simulation method based on CPU-side interpolation: This method performs interpolation calculations on topographic data from different measurements on the CPU, generating intermediate frame topographic data before 3D modeling and rendering. However, the amount of underwater topographic data in waterways is enormous, and traditional CPU-side interpolation calculation methods are computationally intensive, making it difficult to meet the performance requirements of real-time rendering.

[0004] Therefore, there is an urgent need to provide a three-dimensional terrain evolution simulation system and method for long waterways, which can perform continuous, smooth, and real-time rendering performance-compliant three-dimensional dynamic simulation of underwater terrain data from multiple measurements. Summary of the Invention

[0005] In view of this, it is necessary to provide a terrain 3D evolution simulation system and method for long waterways, in order to solve the technical problem in the existing technology that it is impossible to perform continuous smooth 3D evolution dynamic simulation of multi-measurement data while meeting the real-time rendering performance requirements when dealing with long waterways, which are a rendering object with huge computational requirements.

[0006] To address the aforementioned technical problems, in a first aspect, the present invention provides a three-dimensional terrain evolution simulation system for long waterways, the long waterway comprising multiple waterways, the system comprising a CPU terminal and a GPU terminal; The CPU is configured as follows: Load a 3D Earth scene constructed based on the CGCS2000 coordinate system; In response to multiple waterways selected by the user in the long waterway and the first and second measurements of the multiple waterways, a first GeoTiff file set and a second GeoTiff file set are extracted from the database. The first GeoTiff file set and the second GeoTiff file set are used to store the underwater topographic elevation data of the first and second measurements. Map the first GeoTiff file set and the second GeoTiff file set to a first R16 texture object and a second R16 texture object; Identify the currently visible intersecting tiles in the 3D Earth scene that intersect with the waterway, and calculate the texture mapping coordinates and local modeling coordinates of the underwater terrain elevation data within the intersecting tiles; In response to the user's dynamic evolution commands, interpolation coefficients are calculated based on the current simulation progress value and the time codes of the first and second measurements; The GPU is configured as follows: During the vertex shader stage, the first R16 texture object and the second R16 texture object are sampled in parallel according to the texture mapping coordinates to obtain a first elevation sample value and a second elevation sample value. The first elevation sample value and the second elevation sample value are then linearly interpolated based on the interpolation coefficients to obtain the terrain elevation of the current frame. The target mesh vertex in the intersecting tile is determined based on the local modeling coordinates, and the latitude and longitude of the target mesh vertex and the terrain elevation are converted into CGCS2000 geocentric Cartesian coordinates as the vertex position of the target mesh vertex. During the fragment shader stage, dynamic thematic shading is performed based on the terrain elevation, and a rendering frame is output.

[0007] In one possible implementation, the first GeoTiff file set includes a plurality of first GeoTiff files corresponding one-to-one with the plurality of waterways, and the second GeoTiff file set includes a plurality of second GeoTiff files corresponding one-to-one with the plurality of waterways; The CPU is also configured as follows: The plurality of first GeoTiff files and the plurality of second GeoTiff files are extracted from the database respectively, and mapped as R16 texture objects; The GPU is also configured as follows: During the vertex shader stage, parallel sampling and interpolation calculations are performed on the R16 texture objects of the multiple first GeoTiff files and the multiple second GeoTiff files to generate the terrain elevation corresponding to each waterway.

[0008] In one possible implementation, the CPU is further configured as follows: Obtain the raw underwater topographic measurement data of the waterway; The original underwater topographic measurement data is divided according to the number of measurements to obtain the underwater topographic elevation data for each measurement. Determine whether the coordinate system of the underwater topographic elevation data is the CGCS2000 coordinate system; If not, the transformation parameters between the coordinate system of the underwater terrain elevation data and the CGCS2000 coordinate system are passed to the GPU. The GPU is also configured as follows: The underwater topographic elevation data is converted based on the conversion parameters.

[0009] In one possible implementation, the CPU is specifically configured as follows: Determine whether the pixel size of the first GeoTiff file or the second GeoTiff file exceeds the maximum texture size limit of the GPU. If so, the first GeoTiff file or the second GeoTiff file is cropped or its resolution compressed.

[0010] In one possible implementation, the CPU is specifically configured as follows: Determine the latitude and longitude of the circumscribed rectangle of the waterway and the tile latitude and longitude of each tile currently visible in the three-dimensional Earth scene; The intersecting tiles in the three-dimensional Earth scene are determined based on the latitude and longitude of the circumscribed rectangle and the latitude and longitude of the tile.

[0011] In one possible implementation, the CPU is further configured as follows: Determine whether the coordinate system of the underwater topographic elevation data is the CGCS2000 coordinate system; If not, the underwater topographic elevation data is converted based on the conversion parameters between the coordinate system of the underwater topographic elevation data and the CGCS2000 coordinate system.

[0012] In one possible implementation, the interpolation coefficients are: T = k × (t - t1) / (t2 - t1); k=T total / (S-1); In the formula, T is the interpolation coefficient; t is the current simulation progress value; t1 is the time code for the first measurement; t2 is the time code for the second measurement; k is the time unit; T total The total simulation duration is represented by S, which represents the total number of measurements taken in the waterway.

[0013] In one possible implementation, the CPU is further configured as follows: In response to the user's selection of a range on the screen, extract the geographic spatial range corresponding to the selected range on the screen; Identify candidate waterways located within the geographic space and calculate the distance between each candidate waterway and the current viewpoint; Candidate waterways with a distance greater than the distance threshold are removed; Candidate waterways with a distance less than or equal to the distance threshold are selected as multiple waterways by the user.

[0014] In one possible implementation, the CPU is further configured as follows: In response to the user's pause command, the control simulation is paused at the current simulation progress value; In response to the user's location selection operation in the 3D Earth scene, a GPU read-back instruction is generated to obtain the underwater terrain elevation data of the selected location under the current simulation progress value; In response to a user's measurement operation, an interactive measurement function is executed; the interactive measurement function includes at least one of the following: distance measurement between two points, area calculation within a selected area, and excavation volume calculation based on terrain elevation changes; In response to a user's export request, export the terrain data of the current rendering frame or the current simulation progress value as an image or report.

[0015] Secondly, the present invention also provides a method for simulating the three-dimensional evolution of terrain in long waterways, the long waterway comprising multiple waterways, the method comprising: The system loads a 3D Earth scene based on the CGCS2000 coordinate system on the CPU. In response to multiple waterways selected by the user in the long channel and the first and second measurements of those waterways, it extracts a first GeoTiff file set and a second GeoTiff file set from the database. The first and second GeoTiff file sets are used to store underwater terrain elevation data from the first and second measurements. The system maps the first and second GeoTiff file sets to first and second R16 texture objects. It determines the currently visible intersecting tiles in the 3D Earth scene that intersect with the waterways and calculates the texture mapping coordinates and local modeling coordinates of the underwater terrain elevation data within the intersecting tiles. In response to the user's dynamic evolution command, it calculates interpolation coefficients based on the current simulation progress value and the time encoding of the first and second measurements. During the vertex shader stage on the GPU, the first R16 texture object and the second R16 texture object are sampled in parallel according to the texture mapping coordinates to obtain a first elevation sample value and a second elevation sample value. The first elevation sample value and the second elevation sample value are then linearly interpolated based on the interpolation coefficients to obtain the terrain elevation of the current frame. The target mesh vertex in the intersecting tile is determined based on the local modeling coordinates, and the latitude and longitude of the target mesh vertex and the terrain elevation are converted into CGCS2000 geocentric Cartesian coordinates as the vertex position of the target mesh vertex. In the fragment shader stage on the GPU, dynamic thematic shading is performed based on the terrain elevation, and a rendering frame is output.

[0016] The beneficial effects of this invention are as follows: The terrain 3D evolution simulation system for long waterways provided by this invention addresses the issue that in existing technologies, the CPU handles all tasks related to terrain interpolation calculations, 3D modeling, and rendering scheduling, while the GPU is only used as a graphics renderer. Limited by the CPU's serial computing architecture, its real-time rendering performance is insufficient for long waterways. This invention configures the GPU to perform sampling and subsequent interpolation and coordinate transformation based on texture mapping coordinates, thus offloading computationally intensive interpolation and coordinate transformation processes to the GPU. This fully utilizes the GPU's massive parallel computing capabilities, solving the technical problem of insufficient CPU computing power when rendering long waterways, which involve massive amounts of data. It also allows for simultaneous processing of multiple waterways within the long waterway, improving the real-time rendering performance of this object.

[0017] Furthermore, this invention achieves a continuous and smooth three-dimensional dynamic simulation of the evolution of waterway topography by linearly interpolating the topographic elevation samples of adjacent measurements in the GPU shader. This makes the change process of waterway topography visible and perceptible, greatly improving the intuitiveness and accuracy of waterway maintenance decisions.

[0018] Furthermore, this invention loads a 3D Earth scene constructed based on the CGCS2000 coordinate system on the CPU side, and on the GPU side, converts the latitude and longitude of the target mesh vertices and the terrain elevation into CGCS2000 geocentric Cartesian coordinates in real time as the vertex positions. This ensures strict consistency between the terrain elevation and the 3D Earth scene in terms of spatial reference. Compared with existing methods where spatial position deviations are caused by inconsistencies in coordinate systems, this invention ensures the realism and reliability of terrain evolution simulation. Moreover, the CGCS2000 coordinate system is a surveying coordinate system with high spatial accuracy, meeting the navigation requirements of long-haul navigation scenarios. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 A schematic diagram of an embodiment of the terrain three-dimensional evolution simulation system for long waterways provided by the present invention; Figure 2 A schematic flowchart illustrating an embodiment of CPU-side and GPU-side collaborative processing provided by the present invention; Figure 3 A schematic diagram of an embodiment of the present invention, in which the CPU determines the transformation parameters and the GPU performs coordinate transformation; Figure 4 A schematic flowchart illustrating an embodiment of the CPU-side determination of intersecting tiles provided by the present invention; Figure 5 A schematic flowchart illustrating an embodiment of the CPU-side determination of the user-selected waterway provided by the present invention; Figure 6 A schematic diagram of an embodiment of the present invention showing how the waterway changes as the screen selection range moves; Figure 7 This is a schematic diagram of a specific embodiment of the terrain three-dimensional evolution simulation method for long waterways provided by the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] It should be understood that the schematic drawings are not drawn to scale. The flowcharts used in this invention illustrate operations implemented according to some embodiments of the invention. It should be understood that the operations in the flowcharts may be implemented out of order, and steps without logical contextual relationships may be reversed or performed simultaneously. Furthermore, those skilled in the art, guided by the content of this invention, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0023] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0024] This invention proposes a three-dimensional terrain evolution simulation system and method for long waterways, which will be described below.

[0025] Before demonstrating the implementation examples, we will first define the long waterway.

[0026] A long waterway is a continuous navigable waterway that meets the following conditions: (1) the physical length of the waterway is greater than 500 kilometers; (2) the number of waterways under the jurisdiction of the waterway is greater than 10.

[0027] Long waterways typically traverse multiple levels of LOD terrain tiles, and their underwater terrain data is characterized by large spatial span, massive data volume, and complex terrain changes. Using traditional CPU-based serial interpolation methods for 3D evolution simulation results in enormous computational demands, making it difficult to meet the performance requirements of real-time rendering. Therefore, this invention provides a 3D terrain evolution simulation system for long waterways, such as... Figure 1 As shown, the terrain 3D evolution simulation system 10 for long waterways includes a CPU terminal 100 and a GPU terminal 200. like Figure 2 As shown, CPU 100 is configured as follows: S201. Load the 3D Earth scene constructed based on the CGCS2000 coordinate system; S202, in response to the user selecting multiple waterways in the long channel and the first and second measurements of the multiple waterways, extract the first GeoTiff file set and the second GeoTiff file set from the database. The first GeoTiff file set and the second GeoTiff file set are used to store the underwater topographic elevation data of the first and second measurements.

[0028] It should be noted that: the first GeoTiff file set includes underwater topographic elevation data from the first measurement of multiple waterways, and the second GeoTiff file includes underwater topographic elevation data from the second measurement of multiple waterways.

[0029] In a specific embodiment of the present invention, the first GeoTiff file set includes multiple first GeoTiff files corresponding one-to-one with multiple waterways, and the second GeoTiff file set includes multiple second GeoTiff files corresponding one-to-one with multiple waterways. Each GeoTiff file corresponds to the waterway topographic data of one measurement for one waterway. Each pixel in the GeoTiff file stores the topographic elevation value according to a given reference elevation system. The industry standard accuracy is typically 0.2 meters to 2 meters. The advantages of using the Float16 format are: firstly, it saves half the storage space and video memory bandwidth compared to Float32, which is beneficial for the transmission and rendering of large-scale terrain data; secondly, Float16 can be directly mapped to the R16 texture format on the GPU without additional format conversion, greatly improving the efficiency of data transmission from storage to GPU texture.

[0030] S203. Map the first GeoTiff file set and the second GeoTiff file set to the first R16 texture object and the second R16 texture object.

[0031] R16 texture objects refer to a GPU texture format, where R indicates that the texture contains single-channel data and 16 indicates that each pixel occupies 16 bits of storage space.

[0032] It should be noted that for the M waterways selected by the user (M≥10), the CPU will upload the R16 texture objects corresponding to each waterway to the GPU in batches at once.

[0033] S204. Identify the currently visible intersecting tiles in the 3D Earth scene that intersect with the waterway, and calculate the texture mapping coordinates and local modeling coordinates of the underwater terrain elevation data within the intersecting tiles. S205. In response to the user's dynamic evolution command, calculate the interpolation coefficients based on the current simulation progress value and the time codes of the first and second measurements. GPU 200 is configured as follows: S206. In the Vertex Shader (VP) stage, the first R16 texture object and the second R16 texture object are sampled in parallel according to the texture mapping coordinates to obtain the first elevation sample value and the second elevation sample value. The first elevation sample value and the second elevation sample value are linearly interpolated based on the interpolation coefficient to obtain the terrain elevation of the current frame. The target mesh vertex in the intersecting tile is determined based on the local modeling coordinates, and the latitude and longitude of the target mesh vertex and the terrain elevation are converted into CGCS2000 geocentric Cartesian coordinates as the vertex position of the target mesh vertex.

[0034] It should be noted that the first R16 texture object and the second R16 texture object also include R16 texture objects for multiple channels. During the vertex shader stage, the GPU 200 utilizes its massively parallel computing architecture to simultaneously sample and interpolate the R16 texture objects corresponding to the M channels. The sampling and interpolation calculations for each channel are executed in parallel within different computing units of the GPU, without interference. That is, the GPU 200 processes the first and second R16 texture objects corresponding to multiple channels in parallel, simultaneously obtaining the first elevation sample values ​​and second elevation sample values ​​for the first and second measurements of multiple channels.

[0035] S207. In the Fragment Shader (FS) stage, dynamic thematic shading is performed based on terrain elevation, and a rendering frame is output.

[0036] Specifically, the first GeoTiff file set and the second GeoTiff file set conform to the CGCS2000 projection standard, and their pixel format is single-channel Float16 (i.e., 16-bit float, with an elevation range of -65504 to +65504 meters. Even with an accuracy of 0.1 meters, the range can reach -6550 to +6550 meters, meeting the elevation expression needs of any river in the world).

[0037] In a specific embodiment of the present invention, the process of converting the latitude and longitude of the target mesh vertex and the terrain elevation into CGCS2000 geocentric Cartesian coordinates is as follows: The major axis of the 3D Earth scene constructed based on the CGCS2000 coordinate system is a = 6378137.0 meters, and the minor axis is b = 6356752.31414 meters. The first eccentricity is e = sqrt(a² - b²) / a, in meters. For a point with longitude λ, latitude φ, and terrain elevation H, its Cartesian coordinates in the CGCS2000 coordinate system are calculated as follows: N = a / sqrt(1 - e² × sin²(φ)); X = (N+H) × cos(φ) × cos(λ); Y = (N+H) × cos(φ) × sin(λ); Z = (N × (1-e²) ​​+ H) × sin(φ); In the formula, N is the radius of curvature of the egg ring.

[0038] On the GPU side, the above calculations are directly implemented as GLSL / HLSL code. The parallel computing capabilities of the GPU are used to perform coordinate transformation on each vertex, thereby realizing point-by-point dynamic assignment of the waterway terrain.

[0039] In a specific embodiment of the present invention, the interpolation coefficients are: T = k × (t - t1) / (t2 - t1); k=T total / (S-1); In the formula, T is the interpolation coefficient, 0≤T≤1, representing the time position during simulation; t is the current simulation progress value; t1 is the time code for the first measurement; t2 is the time code for the second measurement; k is the time unit; T total S represents the total simulation duration; S is the total number of measurements taken in the waterway.

[0040] The current simulation progress value is the ratio of the current simulation time to the time unit.

[0041] In a specific embodiment of the present invention, the time encoding rules for each measurement are as follows: all measurement data to be simulated (e.g., all measurements from January to December 2025) are time-encoded in the order of measurement, encoded as 0, 1, 2, 3..., with a time unit of 1. If the time is not uniform, it can be encoded as discontinuous natural numbers; for example, measurements missing in March can be encoded as 0, 1, 3... Similarly, if more precise time encoding is required, the time encoding of the data can be encoded as decimals to achieve a more accurate simulation of the evolution of time. For example, if the actual measurement time of a certain measurement is January 15th, it can be encoded as 0.5 to more accurately reflect the actual interval of the measurement time. In most cases, time precision is not important, so using integer time encoding can meet the needs of most application scenarios.

[0042] For example, if the total simulation duration is 22 seconds and the total number of waterway measurements is 12, then each time unit k = 22 / (12 - 1) = 2 seconds, meaning the dynamic change time between every two measurements is 2 seconds, and the simulation of the evolution of all measurements takes a total of 22 seconds. After the simulation starts, the timer starts from 0 and progresses according to the actual time speed. At any given moment, based on the current simulation time, the underwater topographic data from the two time-coded measurements closest to the current simulation time are selected, converted into R16 textures, and then the interpolation coefficients are determined.

[0043] It should be understood that in order to achieve different evolution speeds in the simulation, the total simulation time can be modified. For example, setting the total time to 44 seconds will reduce the evolution speed to half of the original speed, while setting it to 11 seconds will double the evolution speed.

[0044] In a specific embodiment of the present invention, the formula for calculating the terrain elevation H of the current frame is: H = H1×T+H2×(1-T); In the formula, H1 and H2 are the first elevation sample value and the second elevation sample value, respectively.

[0045] It should be understood that linear interpolation calculation is extremely simple, requiring only one multiplication and one addition, and can be executed very efficiently on the GPU. At the same time, since interpolation is performed after texture sampling, rather than at the mesh vertex level, pixel-level smooth interpolation effects can be obtained, avoiding the jaggedness that may be caused by mesh vertex interpolation.

[0046] It should be noted that during the fragment shader stage, the color bands for thematic coloring can be flexibly adjusted according to different business needs, or the original orthophoto can be displayed without using color bands.

[0047] It should also be noted that the above embodiments only use the first and second measurements as examples to illustrate dynamic interpolation. In practical applications, the CPU 100 can extract underwater terrain elevation data of all measurements within the simulation period from the database and map it into an R16 texture object, which is then passed to the GPU 200. The GPU responds to the time information in the user's dynamic evolution command, determines two measurements adjacent to the time information from multiple measurements as the data to be interpolated, and performs three-dimensional terrain evolution simulation.

[0048] Compared with existing technologies, the terrain 3D evolution simulation system 10 for long waterways provided in this embodiment of the invention addresses the issue that in existing technologies, the CPU undertakes all tasks of terrain interpolation calculation, 3D modeling, and rendering scheduling, while the GPU is only used as a graphics renderer. Limited by the CPU's serial computing architecture, its real-time rendering performance is insufficient for long waterways. This embodiment of the invention configures the GPU 200 to perform sampling and subsequent interpolation and coordinate transformation based on texture mapping coordinates. This means that computationally intensive interpolation and coordinate transformation processes are moved to the GPU 200 for execution, fully utilizing the GPU's massive parallel computing capabilities. This solves the technical problem of insufficient CPU computing power when rendering long waterways, which involve huge amounts of data, and improves the real-time rendering performance of these objects. Specifically, based on the GPU's parallel processing capabilities, multiple waterways within the long waterway are processed in parallel, simultaneously simulating the terrain 3D evolution of multiple waterways. Compared to existing technologies that serially process multiple waterways on the CPU, this improves the real-time performance of the overall long waterway evolution simulation.

[0049] Furthermore, this embodiment of the invention achieves a continuous and smooth three-dimensional dynamic simulation of the evolution of waterway topography by linearly interpolating the topographic elevation sampling values ​​of adjacent measurements in the GPU shader. This makes the change process of waterway topography visible and perceptible, greatly improving the intuitiveness and accuracy of waterway maintenance decisions.

[0050] Furthermore, this embodiment of the invention loads a 3D Earth scene constructed based on the CGCS2000 coordinate system on the CPU 100, and on the GPU 200, converts the latitude and longitude of the target mesh vertices and the terrain elevation into CGCS2000 geocentric Cartesian coordinates in real time as the vertex positions. This ensures strict consistency between the terrain elevation and the 3D Earth scene in terms of spatial reference. Compared with the spatial position deviation caused by the inconsistency of coordinate systems in existing methods, this embodiment of the invention ensures the realism and reliability of the terrain evolution simulation. Moreover, the CGCS2000 coordinate system is a surveying coordinate system with high spatial accuracy, which meets the navigation requirements in long-haul scenarios.

[0051] In some embodiments of the present invention, such as Figure 3 As shown, CPU 100 is also configured as follows: S301. Obtain raw underwater topographic survey data of the waterway.

[0052] Specifically, the raw underwater topographic measurement data is stored in a database, and when needed, the raw underwater topographic measurement data is retrieved from the database.

[0053] S302. Divide the original underwater topographic measurement data according to the number of measurements to obtain the underwater topographic elevation data for each measurement.

[0054] It should be understood that: the number of times underwater topographic measurement data is measured refers to the number of times underwater topographic measurement data is measured. For example, underwater topography was measured every month from January to December 2025, which totaled 12 times.

[0055] The embodiments of the present invention organize underwater topographic measurement data through waterways and measurement dimensions, which facilitates the simulation of topographic evolution according to waterways and also facilitates the management and retrieval of topographic data from different periods.

[0056] S303. Determine whether the coordinate system of the underwater topographic elevation data is the CGCS2000 coordinate system.

[0057] Specifically, coordinate reference system information of underwater topographic elevation data can be read to determine its coordinate system.

[0058] S304. If not, then pass the transformation parameters between the coordinate system of the underwater terrain elevation data and the CGCS2000 coordinate system to the GPU.

[0059] Specifically, the CPU side 100 transforms the parameters into uniform variables and uploads them to the GPU side 200.

[0060] The GPU side 200 is also configured as follows: S305. Convert underwater topographic elevation data based on conversion parameters.

[0061] In a specific embodiment of the present invention, the coordinate system of the underwater topographic elevation data is the Wusong elevation system. Therefore, the transformation parameters include the elevation datum difference, and the transformation formula for converting the underwater topographic elevation data is as follows: H CGCS2000 = H 吴淞 +ΔH; In the formula, H CGCS2000 The converted underwater topographic elevation data; H 吴淞 This is the underwater topographic elevation data under the Wusong Elevation System; ΔH is the elevation datum difference.

[0062] This embodiment avoids the performance bottleneck of CPU 100 performing point-by-point serial transformation of massive depth sounding points by migrating the coordinate system transformation from CPU 100 to GPU 200 for parallel execution, and fully utilizes the massive parallel computing capabilities of the GPU. Furthermore, after the coordinate system transformation is completed on GPU 200, it can be executed continuously in the same shader pipeline as subsequent steps such as texture sampling and elevation benchmark transformation, eliminating the need for repeated transfer of intermediate data between CPU 100 and GPU 200, further improving data processing efficiency.

[0063] When the amount of underwater topographic data for a certain measurement of the waterway is too large, in order to avoid exceeding the processing limit of the GPU and thus failing to render effectively, in some embodiments of the present invention, the CPU 100 is specifically configured as follows: Determine whether the pixel size of the first or second GeoTiff file exceeds the maximum texture size limit on the GPU.

[0064] Specifically, the maximum texture size limit on the GPU side is determined by the GPU device. For example, the CPU 100 queries the GPU device's texture size limit through the graphics API at runtime and uses that value as the maximum texture size limit.

[0065] If so, then crop or compress the resolution of either the first or second GeoTiff file.

[0066] The specific process of cropping is as follows: the underwater terrain data of this test is divided into two GeoTiff files based on the method of equal division to ensure that it does not exceed the maximum texture size limit of the GPU.

[0067] The specific process for resolution compression is as follows: when the cropped data still exceeds the texture size limit, or when the user needs to view the complete waterway area but a lower resolution is acceptable, resampling methods such as bilinear interpolation or bicubic interpolation are used to downsample the data to the target size. For example, 8192×4096 pixels of data is compressed to 4096×2048 pixels.

[0068] The above cropping and compression operations can be used individually or in combination. Preferably, when the original data exceeds both the texture size limit and the waterway range can be precisely defined, cropping should be prioritized to preserve the resolution of the effective data to the maximum extent.

[0069] This invention preprocesses 100 pairs of ultra-large GeoTiff files on the CPU side, ensuring that terrain data of any scale can adapt to the texture size limitations of GPU hardware, enabling large-scale terrain data of long channels to run stably on devices with different hardware configurations.

[0070] In some embodiments of the present invention, such as Figure 4 As shown, CPU 100 is specifically configured as follows: S401. Determine the latitude and longitude of the outer rectangle of the waterway and the tile latitude and longitude of each tile currently visible in the 3D Earth scene.

[0071] The process of determining the latitude and longitude of the circumscribed rectangle is as follows: First, obtain the coordinates of all vertices of the waterway boundary; second, traverse all vertices and extract the latitude and longitude extreme values ​​[Xmin, Xmax, Ymin, Ymax]. These four extreme values ​​can determine the latitude and longitude of the circumscribed rectangle.

[0072] The process of determining the latitude and longitude of a tile is as follows: Each tile is determined by a triplet (level, tileX, tileY), and its latitude and longitude spatial range can be calculated from the pyramid level and the tile index. For the level, the globe is divided into 2... level ×2 level There are 10 tiles, and the latitude and longitude range of each tile is: tileLonMin = tileX×(360 / 2^level)-180; tileLonMax = (tileX+1)×(360 / 2^level) -180; tileLatMin = tileY×(180 / 2^level)-90; tileLatMax = (tileY+1)×(180 / 2^level)-90; In the formula, tileLonMin, tileLonMax, tileLatMin, and tileLatMax represent the minimum and maximum longitude values ​​and the minimum and maximum latitude values ​​of the tile, respectively.

[0073] S402. Determine intersecting tiles in a 3D Earth scene based on the latitude and longitude of the circumscribed rectangle and the latitude and longitude of the tiles.

[0074] It should be noted that since the terrain tiles are based on quadtree pyramid LOD tiles, the tiles are constantly changing according to the camera's orientation. Therefore, the mapping of the waterway terrain in the global tiles needs to be dynamically calculated every frame.

[0075] After obtaining the latitude and longitude of the circumscribed rectangle and the tile latitude and longitude, the process for determining the texture mapping coordinates and local modeling coordinates within the intersecting tiles is as follows: First, calculate the intersection area. For each intersecting tile, the intersection area with the circumscribed rectangle of the waterway is: intersectXmin = max(Xmin, tileLonMin); intersectXmax = min(Xmax, tileLonMax); intersectYmin = max(Ymin, tileLatMin); intersectYmax = min(Ymax, tileLatMax); In the formula, intersectXmin, intersectXmax, intersectYmin, and intersectYmax are the four coordinates of the intersecting region.

[0076] Second, calculate the texture mapping coordinates (UV coordinates). Map the latitude and longitude of the intersecting region to the UV coordinate space of the GeoTiff texture: U = (intersectLon - Xmin) / (Xmax - Xmin); V = (intersectLat - Ymin) / (Ymax - Ymin); Third, calculate the local modeling coordinates. Map the latitude and longitude of the intersecting region to the local modeling coordinate space of the tile: localX = (intersectLon - tileLonMin) / (tileLonMax - tileLonMin); localY = (intersectLat - tileLatMin) / (tileLatMax - tileLatMin); Through the above calculations, the local modeling coordinates and texture mapping coordinates in each intersecting tile can be obtained, thereby enabling accurate sampling and assignment of terrain elevation on the GPU.

[0077] In some embodiments of the present invention, such as Figure 5 As shown, CPU 100 is also configured as follows: S501, In response to the user's range selection operation on the screen, extract the geographic spatial range corresponding to the selected range on the screen.

[0078] The specific implementation process for extracting the geographic spatial range corresponding to the screen selection area is as follows: The user draws a rectangular selection box by dragging the mouse or using touch gestures on the screen. This rectangular selection box is defined by screen pixel coordinates, including the pixel coordinates of the upper left corner and the lower right corner. The CPU 100 obtains the screen coordinates of the four corner points of the rectangular selection box, and performs an inverse transformation from screen coordinates to world coordinates on each of the four corner points to obtain the geographic spatial range.

[0079] S502. Identify candidate waterways located within the geographic space and calculate the distance between each candidate waterway and the current viewpoint.

[0080] Among them, the candidate waterways located within the geographic space can be determined based on the spatial intersection query method of Geographic Information System (GIS). This method is a mature method in the industry and will not be elaborated here.

[0081] Specifically, the current viewpoint refers to the spatial position of the virtual camera within the 3D Earth scene, represented in CGCS2000 geocentric Cartesian coordinates. The current viewpoint determines the user's current perspective and distance from the 3D Earth scene. In 3D rendering, the visibility and level of detail (LOD) of all objects are calculated based on their distance relative to the current viewpoint.

[0082] S503. Remove candidate waterways whose distance is greater than the distance threshold.

[0083] S504. Select candidate waterways with a distance less than or equal to the distance threshold as multiple waterways selected by the user.

[0084] It should be noted that when the distance between the candidate waterway and the current viewpoint is too large, it means that the candidate waterway is too far away from the observer and occupies only a small number of pixels on the screen from the current perspective. Its terrain details and evolution changes can no longer be effectively distinguished by the user. Loading and rendering the terrain data of the waterway will contribute almost nothing to the visualization effect. On the contrary, it will consume the computing resources and memory bandwidth of the GPU and reduce the real-time performance of the evolution simulation.

[0085] Therefore, by setting a distance threshold, the embodiments of the present invention eliminate waterways that exceed the threshold, thereby achieving the screening of effective waterways within the visible range and the rational allocation of computing resources. This avoids the waste of computing resources and performance degradation caused by loading all waterways simultaneously in large-scale long-channel scenarios.

[0086] It should be understood that the distance threshold can be set or adjusted according to the camera height, field of view, screen resolution, and physical size of the waterway in the current 3D Earth scene, and no specific limitation is made here.

[0087] It should be noted that the long channel displayed on the screen may include multiple waterways. When the selection range changes, such as when the screen selection range changes due to mouse dragging, steps S501-S504 are repeated to update the waterway selected by the user. Figure 6 As shown, the initial screen selection range includes waterways A, B, C, and D. As the screen moves, the screen selection range becomes C, D, E, and F.

[0088] This invention enables rapid evolution simulation of thousands of kilometers of waterway terrain data by responding to user selection operations on the screen.

[0089] To improve the simulation interactivity of the system, in some embodiments of the present invention, the CPU side 100 is further configured as follows: In response to the user's pause command, the control evolution simulation is paused at the current simulation progress value.

[0090] Specifically, the pause command can be generated via the keyboard space bar or the pause evolution simulation button on the screen.

[0091] In response to the user's location selection operation in the 3D Earth scene, a GPU read-back instruction is generated to obtain the underwater terrain elevation data of the selected location at the current simulation progress value.

[0092] Specifically, the GPU 200 responds to the GPU read-back command, pauses the rendering of the current frame, and reads back the terrain elevation texture stored in the frame buffer of the current frame from the GPU memory to the CPU 100. The CPU 100 calculates the texture coordinates corresponding to the pixel coordinates of the selected location on the screen, and then extracts the elevation value at the texture coordinates from the read-back elevation texture data. Combining the interpolation coefficients corresponding to the current simulation progress and the time encoding of the two adjacent measurements, it reconstructs the actual underwater terrain elevation value of the location at the current simulation time, and returns this elevation value to the user interface for display, thus obtaining the underwater terrain elevation data of the selected location.

[0093] Furthermore, if the location selected by the user does not fall within the coverage area of ​​any waterway terrain data, the elevation value read back 200 times on the GPU side is invalid or a default value.

[0094] It should be noted that the GPU readback instruction is only effective when the evolution simulation is paused, in order to avoid frequent GPU memory readback operations during continuous evolution, which would affect the rendering frame rate.

[0095] Furthermore, CPU 100 is also configured as follows: In response to the user's measurement operation, the interactive measurement function is executed; the interactive measurement function includes at least one of the following: distance measurement between two points, area calculation within a selected area, and excavation volume calculation based on terrain elevation changes; In response to a user's export request, export the terrain data of the current rendering frame or the current simulation progress value as an image or report.

[0096] By setting up the above-mentioned interactive functions, the embodiments of the present invention provide technical support for intelligent waterway maintenance, enabling managers to intuitively analyze the evolution of waterway topography and providing a scientific basis for waterway maintenance decisions.

[0097] In summary, the three-dimensional terrain evolution simulation system for long waterways proposed in this invention has the following beneficial effects: 1. It realizes continuous and smooth evolution simulation of waterway terrain: Traditional methods can only discretize terrain data from different measurements, failing to demonstrate the continuous change process of waterway terrain. This invention achieves continuous and smooth three-dimensional dynamic simulation of waterway terrain evolution by efficiently interpolating terrain elevation data from adjacent measurements in the GPU shader. This makes the change process of waterway terrain visible and perceptible, greatly improving the intuitiveness and accuracy of waterway maintenance decisions. 2. It fully utilizes the parallel computing power of the GPU to achieve efficient rendering of long waterway terrain evolution: This invention performs all calculations in parallel in the GPU shader, including terrain elevation sampling, elevation benchmark conversion, latitude and longitude + elevation to Cartesian coordinate conversion, linear interpolation calculation, and elevation color banding. This fully utilizes the parallel computing power of the GPU, enabling simultaneous evolution simulation of large amounts of waterway terrain. Compared to traditional CPU-based computation methods that can only perform discrete simulations of a small section of waterway, this invention can simultaneously calculate batches of terrain data from multiple waterways, achieving efficient terrain evolution simulation and rendering. Combined with waterway scheduling methods, it can meet the requirements for seamless, continuous, and efficient evolution simulation of thousands of kilometers of waterways, fulfilling the data continuity analysis requirements of smart waterway applications. 3. Ensuring the spatial accuracy of terrain data: This invention strictly adheres to the CGCS2000 coordinate system for 3D scene modeling and implements precise elevation datum transformation and latitude / longitude + elevation to Cartesian coordinate transformation in the GPU shader, ensuring the accuracy of measurement data in 3D space. Compared to existing methods where inconsistent coordinate systems lead to spatial positional deviations, this invention ensures the realism and reliability of terrain evolution simulation. 4. Supporting flexible thematic elevation coloring and interactive functions: This invention supports dynamic thematic coloring based on elevation. Color bands can be flexibly adjusted according to different business needs, or the original orthophoto can be displayed without using color bands. Simultaneously, this invention supports functions such as pausing during the evolution simulation process, real-time elevation query at any location and time, interactive measurement, and map output, providing comprehensive technical support for intelligent waterway maintenance. 5. Optimized Data Format and Transmission Efficiency: This invention uses GeoTIFF in single-channel Float16 format to store waterway terrain data, saving half the storage space and video memory bandwidth compared to Float32. Simultaneously, the Float16 format can be directly mapped to the GPU's R16 texture format without additional format conversion, greatly improving the transmission efficiency of data from storage to GPU textures, which is beneficial for the real-time processing of large-scale waterway terrain data.

[0098] On the other hand, embodiments of the present invention also provide a method for simulating the three-dimensional evolution of terrain for long waterways, such as... Figure 7 As shown, the methods for 3D terrain evolution simulation for long waterways include: S701: Load a 3D Earth scene constructed based on the CGCS2000 coordinate system on the CPU; in response to the user selecting multiple waterways in the long channel and the first and second measurements of the multiple waterways, extract the first GeoTiff file set and the second GeoTiff file set from the database. The first GeoTiff file set and the second GeoTiff file set are used to store the underwater terrain elevation data of the first and second measurements; map the first GeoTiff file set and the second GeoTiff file set to the first R16 texture object and the second R16 texture object; determine the currently visible intersecting tiles in the 3D Earth scene that intersect with the waterways, and calculate the texture mapping coordinates and local modeling coordinates of the underwater terrain elevation data within the intersecting tiles; in response to the user's dynamic evolution command, calculate the interpolation coefficients based on the current simulation progress value and the time encoding of the first and second measurements; S702. In the vertex shader stage on the GPU side, the first R16 texture object and the second R16 texture object are sampled in parallel according to the texture mapping coordinates to obtain the first elevation sample value and the second elevation sample value. The first elevation sample value and the second elevation sample value are linearly interpolated based on the interpolation coefficient to obtain the terrain elevation of the current frame. The target mesh vertex in the intersecting tile is determined based on the local modeling coordinates, and the latitude and longitude of the target mesh vertex and the terrain elevation are converted into CGCS2000 geocentric Cartesian coordinates as the vertex position of the target mesh vertex. S703, in the fragment shader stage on the GPU, performs dynamic thematic shading based on terrain elevation and outputs rendering frames.

[0099] It should be noted that the terrain three-dimensional evolution simulation method for long waterways provided in the above embodiments can realize the technical solutions described in the above embodiments of terrain three-dimensional evolution simulation system for long waterways. The specific implementation principles of each step can be found in the corresponding content in the above embodiments of terrain three-dimensional evolution simulation system for long waterways, and will not be repeated here.

[0100] The above provides a detailed description of a three-dimensional terrain evolution simulation system and method for long waterways provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A three-dimensional terrain evolution simulation system for long waterways, characterized in that, The long channel includes multiple waterways, and the system includes a CPU end and a GPU end; The CPU is configured as follows: Load a 3D Earth scene constructed based on the CGCS2000 coordinate system; In response to multiple waterways selected by the user in the long waterway and the first and second measurements of the multiple waterways, a first GeoTiff file set and a second GeoTiff file set are extracted from the database. The first GeoTiff file set and the second GeoTiff file set are used to store the underwater topographic elevation data of the first and second measurements. Map the first GeoTiff file set and the second GeoTiff file set to a first R16 texture object and a second R16 texture object; Identify the currently visible intersecting tiles in the 3D Earth scene that intersect with the waterway, and calculate the texture mapping coordinates and local modeling coordinates of the underwater terrain elevation data within the intersecting tiles; In response to the user's dynamic evolution commands, interpolation coefficients are calculated based on the current simulation progress value and the time codes of the first and second measurements; The GPU is configured as follows: During the vertex shader stage, the first R16 texture object and the second R16 texture object are sampled in parallel according to the texture mapping coordinates to obtain a first elevation sample value and a second elevation sample value. The first elevation sample value and the second elevation sample value are then linearly interpolated based on the interpolation coefficients to obtain the terrain elevation of the current frame. The target mesh vertex in the intersecting tile is determined based on the local modeling coordinates, and the latitude and longitude of the target mesh vertex and the terrain elevation are converted into CGCS2000 geocentric Cartesian coordinates as the vertex position of the target mesh vertex. During the fragment shader stage, dynamic thematic shading is performed based on the terrain elevation, and a rendered frame is output.

2. The terrain three-dimensional evolution simulation system for long waterways according to claim 1, characterized in that, The first GeoTiff file set includes multiple first GeoTiff files that correspond one-to-one with the multiple waterways, and the second GeoTiff file set includes multiple second GeoTiff files that correspond one-to-one with the multiple waterways; The CPU is also configured as follows: The plurality of first GeoTiff files and the plurality of second GeoTiff files are extracted from the database respectively, and mapped as R16 texture objects; The GPU is also configured as follows: During the vertex shader stage, parallel sampling and interpolation calculations are performed on the R16 texture objects of the multiple first GeoTiff files and the multiple second GeoTiff files to generate the terrain elevation corresponding to each waterway.

3. The terrain three-dimensional evolution simulation system for long waterways according to claim 1, characterized in that, The CPU is also configured as follows: Obtain the raw underwater topographic measurement data of the waterway; The original underwater topographic measurement data is divided according to the number of measurements to obtain the underwater topographic elevation data for each measurement. Determine whether the coordinate system of the underwater topographic elevation data is the CGCS2000 coordinate system; If not, the transformation parameters between the coordinate system of the underwater terrain elevation data and the CGCS2000 coordinate system are passed to the GPU. The GPU is also configured as follows: The underwater topographic elevation data is converted based on the conversion parameters.

4. The terrain three-dimensional evolution simulation system for long waterways according to claim 2, characterized in that, The CPU is specifically configured as follows: Determine whether the pixel size of the first GeoTiff file or the second GeoTiff file exceeds the maximum texture size limit of the GPU. If so, the first GeoTiff file or the second GeoTiff file is cropped or its resolution compressed.

5. The terrain three-dimensional evolution simulation system for long waterways according to claim 1, characterized in that, The CPU is specifically configured as follows: Determine the latitude and longitude of the circumscribed rectangle of the waterway and the tile latitude and longitude of each tile currently visible in the three-dimensional Earth scene; The intersecting tiles in the three-dimensional Earth scene are determined based on the latitude and longitude of the circumscribed rectangle and the latitude and longitude of the tile.

6. The terrain three-dimensional evolution simulation system for long waterways according to claim 1, characterized in that, The interpolation coefficients are: T = k × (t - t1) / (t2 - t1); k=T total / (S-1); In the formula, T is the interpolation coefficient; t is the current simulation progress value; t1 is the time code for the first measurement; t2 is the time code for the second measurement; k is the time unit; T total S represents the total simulation duration; S is the total number of measurements taken in the waterway.

7. The terrain three-dimensional evolution simulation system for long waterways according to claim 1, characterized in that, The CPU is also configured as follows: In response to the user's selection of a range on the screen, extract the geographic spatial range corresponding to the selected range on the screen; Identify candidate waterways located within the geographic space and calculate the distance between each candidate waterway and the current viewpoint; Candidate waterways with a distance greater than the distance threshold are removed; Candidate waterways with a distance less than or equal to the distance threshold are selected as multiple waterways by the user.

8. The terrain three-dimensional evolution simulation system for long waterways according to claim 1, characterized in that, The CPU is also configured as follows: In response to the user's pause command, the control simulation is paused at the current simulation progress value; In response to the user's location selection operation in the 3D Earth scene, a GPU read-back instruction is generated to obtain the underwater terrain elevation data of the selected location at the current simulation progress value.

9. The terrain three-dimensional evolution simulation system for long waterways according to claim 1, characterized in that, The CPU is also configured as follows: In response to a user's measurement operation, an interactive measurement function is executed; the interactive measurement function includes at least one of the following: distance measurement between two points, area calculation within a selected area, and excavation volume calculation based on terrain elevation changes; In response to a user's export request, export the terrain data of the current rendering frame or the current simulation progress value as an image or report.

10. A method for simulating the three-dimensional evolution of terrain in long waterways, characterized in that, The long waterway includes multiple waterways, and the method includes: The system loads a 3D Earth scene based on the CGCS2000 coordinate system on the CPU. In response to multiple waterways selected by the user in the long channel and the first and second measurements of those waterways, it extracts a first GeoTiff file set and a second GeoTiff file set from the database. The first and second GeoTiff file sets are used to store underwater terrain elevation data from the first and second measurements. The system maps the first and second GeoTiff file sets to first and second R16 texture objects. It determines the currently visible intersecting tiles in the 3D Earth scene that intersect with the waterways and calculates the texture mapping coordinates and local modeling coordinates of the underwater terrain elevation data within the intersecting tiles. In response to the user's dynamic evolution command, it calculates interpolation coefficients based on the current simulation progress value and the time encoding of the first and second measurements. During the vertex shader stage on the GPU, the first R16 texture object and the second R16 texture object are sampled in parallel according to the texture mapping coordinates to obtain a first elevation sample value and a second elevation sample value. The first elevation sample value and the second elevation sample value are then linearly interpolated based on the interpolation coefficients to obtain the terrain elevation of the current frame. The target mesh vertex in the intersecting tile is determined based on the local modeling coordinates, and the latitude and longitude of the target mesh vertex and the terrain elevation are converted into CGCS2000 geocentric Cartesian coordinates as the vertex position of the target mesh vertex. In the fragment shader stage on the GPU, dynamic thematic shading is performed based on the terrain elevation, and a rendering frame is output.

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