Processing Method for Seamless Integration of Land and Water 3D Display Based on GIS System

Abstract

The present invention discloses a processing method for seamless land - water integrated three - dimensional display based on a GIS system, which is characterized by the following steps: S1, performing elevation - level color rendering on the initial underwater three - dimensional model, and adopting texture compression and top - layer reconstruction for the initial land three - dimensional real - scene model to achieve second - level loading and display of massive data; S2, using a land - water boundary line to seamlessly splice the underwater three - dimensional model processed in S1 and the land three - dimensional real - scene model processed in S1, thereby obtaining a seamless land - water integrated three - dimensional model. The present invention effectively realizes the seamless land - water integrated three - dimensional display effect.

Description

Technical Field

[0001] The present invention relates to the technical field of geographic information and water conservancy project surveying and mapping, and specifically relates to a processing method for seamless three-dimensional display of land and water based on a GIS system. Background Art

[0002] Many GIS-related software systems, especially those related to the water conservancy industry, although covering underwater terrain data, their three-dimensional displays mostly focus on the land part, and the three-dimensional display of underwater data is relatively weak, especially the seamless three-dimensional display of land and water lacks research. This has led to the difficulty of intuitively and accurately understanding the real situations of underwater and land when these software systems perform three-dimensional displays, and it is difficult to provide reliable technical support for relevant competent departments. For example, the Water Resources Department of Guangdong Province and each river basin management bureau have been urgently in need of the three-dimensional models of land and water in the main rivers of Guangdong Province to comprehensively and intuitively understand the topographic features of the river channels and both banks, so as to provide data support for their scientific decision-making.

[0003] For the three-dimensional displays of most GIS systems, the land area is mainly based on three-dimensional surface models, three-dimensional real-scene models, and BIM models; the underwater area is mostly displayed with two-dimensional isobaths, or simply replaces the underwater data with surface images (such as Figure 2 ), or even directly cuts off the underwater data (such as Figure 3 ); for the few that are displayed in three dimensions, they are mostly three-dimensional single-color rendering (such as Figure 4 ), even if both land and underwater data are displayed in three-dimensional effects, there are still splicing gaps at the land-water junction (such as Figure 5 , Figure 5 the black part within the dotted-line marked circle in Summary of the Invention

[0004] In view of this, in order to solve the problems in the prior art, the present invention proposes a processing method for seamless three-dimensional display of land and water based on a GIS system, which solves the technical problem that the seamless three-dimensional display effect of land and water cannot be achieved at the land-water junction, can provide a reliable technical solution for the digital management of river channels, reservoirs and other river basins by relevant departments, provides an effective solution for the digital twin of river basins, especially solves the problem of three-dimensional display of the underwater area in the previous GIS systems, and effectively realizes the seamless three-dimensional display effect of land and water.

[0005] The present invention solves the above problems through the following technical means:

[0006] The present invention proposes a processing method for seamless three-dimensional display of land and water based on a GIS system, including the following steps:

[0007] S1. Render the initial underwater three-dimensional model using elevation-level color rendering, and perform texture compression and top-level reconstruction on the initial land three-dimensional real-scene model to achieve second-level loading and display of massive data.

[0008] S2. Use a water-land boundary line to seamlessly splice the underwater three-dimensional model processed by S1 and the land three-dimensional real-scene model processed by S1, thereby obtaining a water-land seamless integrated three-dimensional model.

[0009] Further, S100 is also included before S1 or between S1 and S2.

[0010] S100. Determine and extract the water-land boundary line by integrating the initial underwater two-dimensional topographic map and the initial land three-dimensional real-scene model.

[0011] Further, in S1, the process of performing elevation-level color rendering on the underwater three-dimensional model of the GIS system includes the following steps:

[0012] S11. Determine the method of assigning elevation values to the water-land boundary line according to different water surface gradients i.

[0013] S12. Conduct elevation verification on the initial underwater two-dimensional topographic map, then cut it with the water-land boundary line to establish an initial underwater digital elevation model.

[0014] S13. Use the water-land boundary line with elevation information to correct the boundary elevation of the initial underwater digital elevation model obtained in S12.

[0015] S14. Establish the corrected underwater digital elevation model in S13 into a first underwater three-dimensional model, perform elevation-level color rendering on the first underwater three-dimensional model to obtain a second underwater three-dimensional model, and then perform data slicing on the second underwater three-dimensional model to obtain underwater three-dimensional model tile data.

[0016] Further, in S1, the process of performing texture compression and top-level reconstruction on the land three-dimensional real-scene model of the GIS system to achieve second-level loading and display of massive data includes the following steps:

[0017] S101. Cut and correct the boundary elevation of the initial land three-dimensional real-scene model using the water-land boundary line.

[0018] S102. Perform data slicing on the land three-dimensional real-scene model corrected in S101 using texture compression and top-level reconstruction methods to obtain land three-dimensional real-scene model tile data.

[0019] Further, in S102, the texture compression method is to perform texture compression in the KTX 2.0 format.

[0020] Further, in S11, there are two ways to assign elevation values to the water-land boundary line as follows:

[0021] Method 1: For rivers or reservoirs with no water level drop or a water level drop within a specified small range on the water surface, the elevation of the water-land boundary line can be uniformly assigned a specified elevation value;

[0022] Method 2: For rivers or reservoirs with a water level drop within a specified large range on the water surface, the water-land boundary line needs to be assigned elevation values according to the actual situation by setting a certain water surface slope to ensure that the actual water-land boundary line situation can be truly reflected.

[0023] Further, in S11, the calculation formula for the water surface slope i is as follows:

[0024] i = (H2 - H1) / L = (ΔH / L)×1000‰ (1)

[0025] In formula (1), H2 is the water surface elevation at the starting position of the upstream river or reservoir, H1 is the water surface elevation at the ending position of the downstream river or reservoir, and L is the distance from the starting position to the ending position of the river or reservoir.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] The underwater three-dimensional model of the present invention uses elevation-level color rendering maps to overlay the three-dimensional terrain, which can truly and beautifully reflect the underwater terrain and make up for the blank of underwater three-dimensional data display in general GIS systems; the onshore three-dimensional real-scene model of the present invention uses high-precision and high-resolution oblique image results, which can directly obtain the actual onshore situation. During the model slicing process, KTX2.0 texture compression and top-level reconstruction are adopted, which can greatly reduce the problem of excessive video memory occupation when the system runs and browses data, and more achieve the second-level loading effect of full-map display of a large number of three-dimensional real-scene models, greatly improving the fluency and experience of the system; the present invention can solve the problem of gaps existing at the joint of underwater and onshore three-dimensional models; the seamless water-land integrated three-dimensional model of the present invention can provide new and reliable data support for the operation and maintenance of relevant GIS systems in industries such as water conservancy, land and resources, environmental protection, and agriculture, and provide technical guarantee for its scientific decision-making. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0029] Figure 1It is the specific workflow diagram of a method for processing seamless three-dimensional display of land and water based on GIS system in Embodiment 2 of the present invention;

[0030] Figure 2 It is the display diagram obtained by the GIS system involved in the background technology through the method of replacing underwater data with water surface images;

[0031] Figure 3 It is the display diagram obtained by the GIS system involved in the background technology through the method of directly cutting off underwater data;

[0032] Figure 4 It is the three-dimensional display diagram obtained by the GIS system involved in the background technology through the method of three-dimensional single-color rendering;

[0033] Figure 5 It is the three-dimensional display diagram with splicing gaps at the land-water junction of the GIS system involved in the background technology;

[0034] Figure 6 It is the top view of the small or no-drop water edge line involved in the present invention;

[0035] Figure 7 It is the side view of the small or no-drop water edge line involved in the present invention;

[0036] Figure 8 It is the top view of the large-drop water edge line involved in the present invention;

[0037] Figure 9 It is the side view of the large-drop water edge line involved in the present invention;

[0038] Figure 10 It is a three-dimensional display effect diagram of seamless integration of land and water involved in the present invention;

[0039] Figure 11 It is another three-dimensional display effect diagram of seamless integration of land and water involved in the present invention. Detailed implementation manners

[0040] To make the above objects, features and advantages of the present invention more obvious and understandable, the technical solutions of the present invention will be described in detail below in conjunction with the drawings and specific embodiments. It should be noted that the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0041] It should be understood that the orientation or positional relationship indicated by terms such as "top" and "bottom" is based on the orientation or positional relationship shown in the drawings. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0042] The terms "first", "second", and "third" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first", "second", and "third" may explicitly or implicitly include one or more of such features.

[0043] Embodiment 1

[0044] The present invention provides a processing method for seamless integrated three-dimensional display of water and land based on a GIS system, including the following steps:

[0045] S1. Perform elevation level color rendering on the initial underwater three-dimensional model, and perform texture compression and top layer reconstruction on the initial land three-dimensional real scene model to achieve second-level loading display of massive data.

[0046] S2. Use a water-land boundary line to seamlessly splice the underwater three-dimensional model processed in S1 and the land three-dimensional real scene model processed in S1, thereby obtaining a seamless integrated three-dimensional model of water and land.

[0047] Further, S100 is also included before S1 or between S1 and S2;

[0048] S100. Determine and extract the water-land boundary line by integrating the initial underwater two-dimensional topographic map and the initial land three-dimensional real scene model.

[0049] Further, in S1, the process of performing elevation level color rendering on the underwater three-dimensional model of the GIS system includes the following steps:

[0050] S11. Determine the method of assigning elevation values to the water-land boundary line according to different water surface gradients i;

[0051] S12. Perform elevation verification on the initial underwater two-dimensional topographic map, then cut it with the water-land boundary line to establish an initial underwater digital elevation model;

[0052] S13. Use the water-land boundary line with elevation information to correct the boundary elevation of the initial underwater digital elevation model obtained in S12;

[0053] S14. Establish the corrected underwater digital elevation model in S13 into a first underwater three-dimensional model, perform elevation-level color rendering on the first underwater three-dimensional model to obtain a second underwater three-dimensional model, and then perform data slicing on the second underwater three-dimensional model to obtain underwater three-dimensional model tile data.

[0054] Further, in S1, the process of realizing the second-level loading and display of massive data for the onshore three-dimensional real-scene model of the GIS system by using texture compression and top-level reconstruction includes the following steps:

[0055] S101. Crop the initial onshore three-dimensional real-scene model using the water-land boundary line and correct the boundary elevation.

[0056] S102. Perform data slicing on the onshore three-dimensional real-scene model corrected in S101 by using texture compression and top-level reconstruction to obtain onshore three-dimensional real-scene model tile data.

[0057] Further, in S102, the method of texture compression is to perform texture compression in the KTX 2.0 format.

[0058] Further, in S11, the methods of assigning elevation values to the water-land boundary line include the following two:

[0059] Method 1: For rivers or reservoirs with no water level drop or a water level drop within a specified small range on the water surface, the elevation of the water-land boundary line can be uniformly assigned a specified elevation value (as shown in Figure 6 、 Figure 7 ); specifically, the specified elevation value depends on the actual situation on the spot, such as 10 meters, 100 meters, etc.; the specified small range specifically refers to a water surface slope less than or equal to 0.01‰.

[0060] Method 2: For rivers or reservoirs with a water level drop within a specified large range on the water surface, the water-land boundary line needs to be assigned elevation values according to a certain water surface slope based on the actual situation to ensure that the actual water-land boundary line situation can be truly reflected (as shown in Figure 8 、 Figure 9 ); the specified large range specifically refers to a water surface slope greater than 0.01‰.

[0061] Further, in S11, the calculation formula for the water surface slope i is as follows:

[0062] i = (H2 - H1) / L = (ΔH / L) × 1000‰ (1)

[0063] In formula (1), H2 is the water surface elevation at the starting position of the upstream river or reservoir, H1 is the water surface elevation at the ending position of the downstream river or reservoir, and L is the distance of the river or reservoir from the starting position to the ending position.

[0064] As Figure 10 , Figure 11 , the problem of gaps at the joints of the underwater and onshore 3D models of the present invention has been solved.

[0065] Embodiment 2

[0066] As Figure 1 shown, the specific implementation process of a processing method for seamless integration of land and water 3D display based on the GIS system is as follows:

[0067] ①. Using the original topographic map and 3D real-scene model, comprehensively determine the land-water boundary, draw the water edge line, and assign the water surface elevation. This water edge line with elevation information is the key data for realizing the seamless integration of land and water in this technical solution; for rivers or reservoirs with no or small water surface drop, the elevation of the water edge line can be uniformly assigned a certain elevation value (as Figure 6 , Figure 7 shown); for rivers or reservoirs with a large water surface drop, the water edge line needs to set a certain water surface slope according to the actual situation (as Figure 8 , Figure 9 shown) to ensure that the actual water edge situation can be truly reflected. The formula for the water surface slope i is as follows:

[0068] i = (H2 - H1) / L = (ΔH / L) × 1000‰ (1)

[0069] ②. Import the elevation information in the underwater topographic map, including contour lines and elevation points, into the GIS software for elevation verification and cropping of the water edge line range, and establish an initial underwater DEM (Digital Elevation Model); use the water edge line with elevation information in ① to correct the elevation of the initial underwater DEM so that the boundary elevation of the underwater DEM is completely consistent with the elevation of the water edge line, and then perform 3D modeling to obtain an underwater 3D model with corrected boundary elevation;

[0070] ③. Slice the data of the underwater 3D model with corrected boundary elevation to obtain the tile data of the underwater 3D model with corrected boundary elevation;

[0071] ④. Use the underwater 3D model with corrected boundary elevation in ② to perform hierarchical color rendering according to the elevation to obtain an underwater elevation rendering map; then slice the data of the underwater elevation rendering map to obtain the tile data of the underwater elevation rendering map;

[0072] ⑤. Cut off the water surface part of the original 3D real-scene model through the water edge line, and then use the water edge line with elevation information to correct the elevation of the boundary of the cut model so that the boundary elevation of the 3D real-scene model is completely consistent with the elevation of the water edge line, and obtain a 3D real-scene model with corrected boundary elevation;

[0073] ⑥. Slice the 3D real-scene model with the boundary elevation corrected in ⑤ to obtain the onshore 3D real-scene model tile data; during the data slicing process, if no data processing and compression are performed, it will greatly affect the browsing fluency and occupy the computer video memory during subsequent network transmission and display browsing. After multiple tests and comprehensive optimization, the technical solution adopts methods such as KTX 2.0 texture compression and top-level reconstruction for data slicing; through test comparison, the data after KTX 2.0 texture compression conversion occupies more than 80% less video memory when browsing and displaying than the uncompressed data; for the converted data with top-level reconstruction, even for data of hundreds of Gb, the full-map display can achieve second-level loading;

[0074] ⑦. Overlay the underwater elevation rendering map tile data in ④ on the underwater 3D model tile data in ③ to obtain the underwater terrain 3D visualization rendering result, and then splice it with the onshore 3D real-scene model tile data in ⑥ to finally obtain the complete seamless integrated 3D model result of land and water; this 3D result can be directly applied to the current mainstream WebGIS system, providing data support and technical guarantee for relevant application systems such as water conservancy, land and resources, environmental protection, and agriculture.

[0075] The above-described embodiments only represent several implementation manners of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several deformations and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A processing method for seamless integrated three-dimensional display of land and water based on a GIS system, characterized in that, It includes the following steps: S100, determine and extract the water-land boundary line based on the initial underwater two-dimensional topographic map and the initial onshore three-dimensional real scene model; then execute S1; S1, perform elevation-level color rendering on the initial underwater three-dimensional model, and adopt texture compression and top-level reconstruction for the initial onshore three-dimensional real scene model to achieve second-level loading and display of massive data; then execute S2; S2, use the water-land boundary line with elevation information to seamlessly splice the underwater three-dimensional model processed by S1 and the onshore three-dimensional real scene model processed by S1, so as to obtain a seamless water-land integrated three-dimensional model; In S1, the process of performing elevation-level color rendering on the underwater three-dimensional model of the GIS system includes the following steps: S11, determine the method of assigning elevation values to the water-land boundary line according to different water surface gradients i; S12, conduct elevation verification on the initial underwater two-dimensional topographic map, and then cut it with the water-land boundary line to establish an initial underwater digital elevation model; S13, use the water-land boundary line with elevation information to correct the boundary elevation of the initial underwater digital elevation model obtained in S12; S14, establish the corrected underwater digital elevation model in S13 into a first underwater three-dimensional model, perform elevation-level color rendering on the first underwater three-dimensional model to obtain a second underwater three-dimensional model, and then perform data slicing on the second underwater three-dimensional model to obtain underwater three-dimensional model tile data.

2. The processing method for seamless land-water integrated three-dimensional display based on the GIS system according to claim 1, wherein, In S1, the process of adopting texture compression and top-level reconstruction for the onshore three-dimensional real scene model of the GIS system to achieve second-level loading and display of massive data includes the following steps: S101, cut and correct the boundary elevation of the initial onshore three-dimensional real scene model using the water-land boundary line; S102, perform data slicing on the onshore three-dimensional real scene model corrected in S101 by adopting texture compression and top-level reconstruction to obtain onshore three-dimensional real scene model tile data.

3. The processing method for seamless integrated three-dimensional display of land and water based on the GIS system according to claim 2, wherein In S102, the texture compression method is to compress the texture in the KTX 2.0 format.

4. The processing method for seamless integrated three-dimensional display of water and land based on the GIS system according to claim 1, characterized in that, In S11, the methods of assigning elevation values to the water-land boundary line include the following two: Method 1: For rivers or reservoirs with no water surface drop or a drop within a specified small range, the elevation of the water-land boundary line can be uniformly assigned a specified elevation value; Method 2: For rivers or reservoirs with a water surface drop within a specified large range, the water-land boundary line needs to set a certain water surface gradient for elevation assignment according to the actual situation to ensure that the actual water-land boundary line situation can be truly reflected.

5. According to the method for processing seamless water-land integrated three-dimensional display based on the GIS system described in claim 1, in S11, the calculation formula of the water surface gradient i is as follows: i = (H2 - H1) / L = (△H / L) × 1000‰ (1) In formula (1), H2 is the water surface elevation at the starting position of the upstream river or reservoir, H1 is the water surface elevation at the ending position of the downstream river or reservoir, and L is the distance of the river or reservoir from the starting position to the ending position.

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