Three-dimensional terrain visual map generation method based on dynamic color matching

Abstract

The invention discloses a three-dimensional terrain visual map generation method based on dynamic color matching. The method comprises the following steps: acquiring a digital elevation model (DEM) or a digital surface model (DSM) based on airborne laser radar data; slope indexes are extracted through a digital terrain analysis technology, and slope raster data are generated; based on raster data space visibility analysis, positive terrain opening (POS) and negative terrain opening (NEG) data are calculated, and ridge and valley index (RVI) data are obtained according to a formula RVI = (POS-NEG) / 2; and the gradient data and the ridge and valley index data are superposed, color modes (red, green, blue-red gradual change and green-orange gradual change) are dynamically matched according to terrain types, and three-dimensional topographic layer rendering is realized through adjustment of a highlight mixing mode. According to the method, a three-dimensional terrain multi-scale analysis method and a dynamic color matching technology are integrated, complex terrain features are finely displayed, the terrain detail expression ability is improved, and technical support is provided for geological disaster prediction and ecological management.

Description

Technical Field

[0001] The present invention relates to a technology for geographic information system applications and ecological environment, and particularly to a method for generating a three-dimensional terrain visualization map based on spatial visibility and dynamic color matching. Background Art

[0002] With the development of real-time rendering, high-performance computing technology, artificial intelligence, and big data technology, the development of the three-dimensional visualization field has received increasing attention. Currently, in the geographic information system industry, Digital Elevation Model (DEM) or Digital Surface Model (DSM) data is generally used. Through the layer coloring or gradient rendering technology, the elevation information is converted into a color gradient to intuitively display the terrain undulation characteristics and assist users in quickly identifying the landform and micro-topography features.

[0003] However, currently, terrain visualization technologies such as contour lines, layer coloring, and mountain shadow have defects such as geometric distortion, strong dependence on light, and mismatch of single-color system representation. It is difficult to accurately analyze multi-scale complex terrain features, restricting the effectiveness of geoscience applications and becoming a bottleneck for the high-quality development of ecological governance and geological disaster prediction.

[0004] Therefore, there is an urgent need to provide a technical solution to solve the above problems.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The object of the present invention is to provide a method for generating a three-dimensional terrain visualization map based on dynamic color matching to solve the above technical problems existing in the prior art.

[0007] The object of the present invention is achieved through the following technical solutions:

[0008] The method for generating a three-dimensional terrain visualization map based on dynamic color matching of the present invention includes:

[0009] Step 1), obtaining a digital elevation model or a digital surface model based on lidar technology, and importing the model into a geographic information system processing platform for processing;

[0010] Step 2), inputting the target digital elevation data raster in the slope analysis module of the geographic information system processing platform to generate slope raster data;

[0011] Step 3), importing the digital elevation data into the spatial visibility analysis module, selecting the positive terrain opening degree POS and negative terrain opening degree NEG calculation functions to generate POS and NEG data, and importing them as a new layer into the geographic information system processing platform;

[0012] Step 4), using the raster calculator tool, obtain the ridge-valley index raster data according to the formula RVI = (POS - NEG) / 2;

[0013] Step 5), overlay the slope data with the ridge-valley index data layer, set the layer into red, green solid color or blue-red, cyan-orange color mode according to different feature characteristics of the ground objects, and adjust through the hard light blending mode to achieve the rendering of the three-dimensional terrain layer;

[0014] Step 6), output the visualized three-dimensional stereoscopic map, which supports terrain feature recognition and ecological governance analysis.

[0015] Compared with the prior art, the method for generating a three-dimensional terrain visualization map based on dynamic color matching provided by the present invention integrates a three-dimensional terrain multi-scale analysis method and a dynamic color matching technology, finely displays complex terrain features, improves the terrain detail expression ability, and provides technical support for geological disaster prediction and ecological governance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the theoretical schematic diagram of the opening degree of positive terrain / negative terrain;

[0017] Figure 2 It is the flowchart of making a three-dimensional terrain visualization map in the embodiment of the present invention;

[0018] Figure 3 It is the visualization map of the forest land DSM data in the embodiment of the present invention;

[0019] Figure 4 It is the visualization map of the forest land DEM data in the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention; obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments, and this does not constitute a limitation to the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

[0021] First, the following explanations are made for the terms that may be used in this article:

[0022] Descriptions using terms such as "comprising", "including", "containing", "having" or other similar semantics should be interpreted as non-exclusive inclusion. For example, including a technical feature element (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, processes, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or articles, etc.) should be interpreted as not only including the explicitly listed technical feature element, but also including other technical feature elements well-known in the art that are not explicitly listed.

[0023] The term "consisting of" means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim a closed type, so that it does not include technical feature elements other than the explicitly listed ones, except for conventional impurities related thereto. If this term only appears in a sub-clause of a claim, then it only limits the elements explicitly listed in that sub-clause, and the elements recorded in other sub-clauses are not excluded from the overall claim.

[0024] Contents not described in detail in the embodiments of the present invention belong to the prior art well-known to those skilled in the art. For those conditions not specified in the embodiments of the present invention, they are carried out according to the conventional conditions in the art or the conditions recommended by the manufacturer. For the reagents or instruments used in the embodiments of the present invention without indicating the manufacturer, they are all conventional products that can be obtained by commercial purchase.

[0025] The method for generating a three-dimensional terrain visualization map based on dynamic color matching of the present invention includes:

[0026] Step 1), obtaining a digital elevation model or a digital surface model based on lidar technology, and importing the model into a geographic information system processing platform for processing;

[0027] Step 2), inputting the target digital elevation data raster in the slope analysis module of the geographic information system processing platform to generate slope raster data;

[0028] Step 3), importing the digital elevation data into the spatial visibility analysis module, selecting the calculation functions of the positive terrain opening degree POS and the negative terrain opening degree NEG to generate POS and NEG data, and importing them into the geographic information system processing platform as a new layer;

[0029] Step 4), using the raster calculator tool to obtain the ridge-valley index raster data according to the formula RVI = (POS - NEG) / 2;

[0030] Step 5), overlaying the slope data and the ridge-valley index data layer, setting the layer into a red, green pure color or blue-red, cyan-orange color mode according to different land feature characteristics, and adjusting through the hard light blending mode to realize the rendering of the three-dimensional terrain layer;

[0031] Step 6): Output a visualized three-dimensional map, which supports terrain feature recognition and ecological governance analysis.

[0032] In the said step 1), the original elevation data is obtained through airborne lidar scanning; the original data is processed by noise removal, ground point extraction and classification to generate standard DEM / DSM grid data.

[0033] In the said step 3), when calculating the positive terrain opening degree POS and the negative terrain opening degree NEG, load the DEM data into the RVT module, check the corresponding opening degree analysis function, and generate the positive terrain opening degree POS and the negative terrain opening degree NEG grid data.

[0034] In the said step 5), the method for setting the layer color mode is as follows:

[0035] Reclassify the ridge-valley index data, divide the colors according to the range values. The more the elevation difference of the plot area, the more range values are usually set; generally, two to four elevation range values are set.

[0036] When the ground object is vegetation or soil, color the slope layer green.

[0037] When the terrain undulation is small, color the slope layer red.

[0038] When the ground object is a mountain, adopt a blue-red gradient mode: use red as the highest elevation point value, blue as the lowest elevation point value, and use a blue-red transition color for the middle range value and reduce the brightness.

[0039] When the ground object is water, adopt a cyan-orange gradient mode: use cyan as the lowest elevation point value, orange as the highest elevation point value, and use a cyan-orange transition color for the middle range value and reduce the brightness.

[0040] The superposition order of the color / monochrome layer and the slope layer is:

[0041] Set the transparency of the color gradient / monochrome gradient slope layer to 50%, superimpose it on the RVI layer, and adjust the brightness through the hard light blending mode to form a three-dimensional terrain rendering effect.

[0042] In the said step 6), the method for generating the visualized three-dimensional map is:

[0043] Perform three-dimensional modeling on the rendered terrain data through the three-dimensional visualization module of the geographic information platform to generate a visualized three-dimensional map.

[0044] In summary, the method for generating a three-dimensional terrain visualization map based on dynamic color matching according to the embodiments of the present invention obtains a Digital Elevation Model (DEM) or a Digital Surface Model (DSM) based on airborne lidar data; extracts slope indexes through digital terrain analysis technology to generate slope raster data; based on the spatial visibility analysis of raster data, calculates the Openness-Positive (POS) and Openness-Negative (NEG) data of the terrain, and then obtains the Ridge and Valley Index (RVI) data according to the formula RVI = (POS - NEG) / 2; superimposes the slope data and the ridge and valley index data, dynamically matches the color mode (red, green, red-blue gradient, cyan-orange gradient) according to the ground object type, and realizes the rendering of the three-dimensional terrain layer through the adjustment of the strong light blending mode. The present invention integrates a multi-scale analysis method of three-dimensional terrain and a dynamic color matching technology, finely displays complex terrain features, improves the terrain detail expression ability, and provides technical support for geological disaster prediction and ecological governance.

[0045] The present invention proposes a multi-mode dynamic color matching technology, combines the ridge and valley index with an adaptive color layering scheme, optimizes the terrain detail expression ability, and overcomes the limitations of traditional methods.

[0046] In order to more clearly show the technical solutions provided by the present invention and the technical effects produced, the following takes specific embodiments to describe in detail what is provided by the embodiments of the present invention.

[0047] As Figures 1 to 4 shown:

[0048] It includes the following steps:

[0049] Step S1: Obtain a Digital Elevation Model (DEM) or a Digital Surface Model (DSM), and import the model into a Geographic Information System (GIS) processing platform for preprocessing;

[0050] Step S2: Input the DEM / DSM raster data into the slope analysis module of the GIS platform to generate slope raster data;

[0051] Step S3: Import the DEM / DSM data into the spatial visibility analysis module, calculate the Openness-Positive (POS) and Openness-Negative (NEG) of the terrain, and generate the corresponding raster layers;

[0052] Step S4: Through the raster calculator according to the formula

[0053]

[0054] Calculate the Ridge Valley Index (RVI) data to generate an RVI raster layer;

[0055] Step S5: Overlay the slope data with the RVI data, dynamically match the color mode according to the land cover type, and adjust through the hard light blending mode to achieve 3D terrain rendering;

[0056] Step S6: Output a 3D terrain visualization map, supporting fine recognition of terrain features and high-quality analysis of ecological governance.

[0057] Furthermore, the step S1 includes:

[0058] Step S11: Obtain the original elevation data through airborne lidar scanning;

[0059] Step S12: Perform noise removal, ground point extraction, and classification on the original data to generate standard DEM / DSM raster data.

[0060] Furthermore, in the step S3, when calculating the Positive Terrain Opening (POS) and Negative Terrain Opening (NEG), load the DEM data into the RVT module, check the corresponding opening analysis function, and generate the Positive Terrain Opening (POS) and Negative Terrain Opening (NEG) raster data.

[0061] Furthermore, in the step S5, the specific method for dynamically matching the color mode is:

[0062] Step S51: Reclassify the RVI data, divide the color gradient according to the elevation range, and the classification range value is more when the elevation difference of the plot area is larger;

[0063] Step S52: Select a color scheme according to the land cover type:

[0064] For vegetation or soil areas, the slope layer is colored green;

[0065] For flat terrain areas, the slope layer is colored red;

[0066] For mountain areas, a blue-red gradient mode is adopted, with the highest elevation point being red, the lowest elevation point being blue, and the intermediate values represented by blue-red transitional colors;

[0067] For water areas, a cyan-orange gradient mode is adopted, with the lowest elevation point being cyan, the highest elevation point being orange, and the intermediate values represented by cyan-orange transitional colors;

[0068] Furthermore, in the step S5, the overlay order of the color / monochrome layer and the slope layer is:

[0069] Step S53: Set the transparency of the color gradient / monochrome gradient slope layer to 50%, overlay it on the RVI layer, and adjust the brightness through the hard light blending mode to form a three-dimensional terrain rendering effect.

[0070] Further, in the step S6, the method for generating a visualized three-dimensional map is as follows:

[0071] Step S61: Perform three-dimensional modeling on the rendered terrain data through the three-dimensional visualization module of the geographic information platform to generate a visualized three-dimensional map.

[0072] Advantages of the present invention:

[0073] By integrating slope analysis, spatial visibility analysis, and dynamic color matching technology, the ability to express terrain details is significantly improved, and problems such as geometric distortion and mismatch of single-color system representation in traditional methods are solved. It can accurately analyze complex terrain features, assist in geological disaster monitoring, ecological restoration planning, and three-dimensional map production, and has the characteristics of simple operation and intuitive visualization effect.

[0074] The technical principle of the present invention is as follows:

[0075] Principle of openness theory: The positive terrain openness (Openness-Positive, POS) represents the sky area that can be seen within the distance L from the sample point of interest, and the negative terrain openness (Openness-Negative, NEG) represents the underground area of interest that can be seen within the distance L from the sample point of interest ( Figure 1 ). The degree of opening depends on the distance L and the surrounding terrain. The degree of opening above the ground increases with the height H by which the sample location protrudes towards the surroundings, with larger values at the mountaintop and ridge, and smaller values in the depression and valley bottom. Conversely, the underground opening degree of the sample location decreases with the height H and the complexity of the surrounding terrain.

[0076] Principle of visualization: The present invention represents the terrain through the positive superposition of two layers, namely the ridge-valley index map and the color slope map. Openness (Openess-Openess) represents the degree of openness of the space around the calculation reference point; it is calculated once upward and once downward at the same point to obtain the positive terrain openness POS and negative terrain openness ENG data. It can be seen from this that the POS data has a higher value at the convex point; while ENG is the opposite. Thus, the ridge-valley index (Ridgeand ValleyIndex, RVI) is proposed, and its calculation formula is shown in formula (1).

[0077]

[0078] In the formula, RVI is the ridge-valley index, POS is the positive terrain openness data, and ENG is the negative terrain openness data.

[0079] Principle of layer overlay: Layer overlay refers to mixing the pixel values of two or more layers through mathematical operations to obtain the pixel values of a new layer. Common layer overlay modes include normal mode, addition mode, soft light mode, hard light mode, multiplication mode, and screen mode. The ridge-valley index can obtain higher values at convex locations and lower values at concave locations. Slope is the degree of steepness of a surface unit, and its representation methods include percentage method, degree method, mil method, and fraction method. In this embodiment, the degree method is adopted. The larger the slope, the steeper the slope surface and the deeper the gully; the smaller the slope, the flatter the slope surface. The reclassified color-setting layer overlay of the ridge-valley index is based on different features to assign different colors to the colored-rendered slope layer, so as to show the detailed features of the regional terrain undulation.

[0080] Embodiment 1

[0081] Figure 2 It is a flowchart of a method for generating a three-dimensional terrain visualization map according to an exemplary embodiment of the present invention. The method in this embodiment includes:

[0082] Step S1: Obtain the point cloud data (LAS format) of a forest area in Shanxi Province through aerial photography by an airborne lidar sensor (Light Detection and Ranging, LiDAR), load the original data using Global Mapper software, and perform the following operations:

[0083] Noise removal: Remove outliers through elevation filtering (the threshold is set to ±3σ).

[0084] Ground point extraction: Use the progressive morphological filtering algorithm to separate ground points from non-ground points.

[0085] Classification processing: Divide non-ground points into high-vegetation classes (tree canopies) and low-vegetation classes (shrubs), and generate DEM (Digital Elevation Model) and DSM (Digital Surface Model) raster data with a resolution of 0.5m.

[0086] Step S2: Import the DEM / DSM data into the ArcGIS Pro platform and perform slope analysis:

[0087] Select the "Slope" tool in the "Spatial Analyst" toolbox, input the DEM data, generate slope data, and save it as slope.tif.

[0088] Step S3: Load the DEM data into the RVT module, check the "Openness-Positive" and "Openness-Negative" options, set the search radius L = 50m, and generate POS and NEG raster layers.

[0089] Step S4: Calculate the Ridge Valley Index (RVI) using the raster calculator: Enter the formula:

[0090] Output the RVI raster data, with the value range being [-50, 50];

[0091] Step S5: Load the raster data in the geographic information platform and perform layer overlay and color configuration:

[0092] Slope layer: Dynamically assign colors referring to the natural features of the reference objects. Gradually fade from white - green for the vegetation area, assign white (RGB: 255, 255, 255) to the lowest point, and assign green (RGB: 0, 255, 0) to the highest point.

[0093] RVI layer: When - 50 < RVI < 50: Assign a black - white gradient, with the lowest point being black (RGB: 0, 0, 0) and the highest point being white (RGB: 255, 255, 255).

[0094] Overlay mode: Set the transparency of the slope layer to 50%, overlay it on the RVI layer, and adjust the brightness using the hard light blending mode to form a three - dimensional rendering effect.

[0095] Step S6: Create a 3D map view in the geographic information platform for solid modeling of the rendered terrain data, with the configured parameters as follows:

[0096] Vertical scale: 2;

[0097] Tile resolution: 250px;

[0098] Generate a three - dimensional terrain visualization map.

[0099] By comparing and analyzing the three - dimensional terrain visualization map generated by the present invention with the existing terrain expression methods such as contour lines, layer - tinted coloring, and hill - shade, it can be verified that the present invention has significant advantages in the following three aspects.

[0100] 1) Improved geometric fidelity: In the traditional contour line method, the ridge lines are prone to be blurred due to interpolation of discrete elevation points, and in the layer - tinted coloring method, jagged artifacts are generated due to color steps in the elevation mutation area (such as steep slopes). However, by fusing Slope and RVI and combining dynamic gradient color matching in the present invention, the geometric fidelity of the terrain can be improved, and the ridge / valley boundaries are continuous and clear.

[0101] 2) Enhanced lighting robustness: The hill - shade method is limited by the light source angle and requires multiple angles and multi - view expressions of the terrain undulation. However, based on the opening data (POS / NEG) of spatial visibility analysis in the present invention, without relying on external light simulation, directly through the overlay rendering of RVI and Slope, the concave - convex features of the terrain can be fully presented in a single view, making the expression of the roughness of the micro - terrain more delicate.

[0102] 3) Improvement in multi-scale detail analysis ability: Compared with traditional single-color system representation (such as using only blue-green gradient color system to represent terrain undulation in layer coloring), the present invention dynamically matches natural and familiar colors with reference to ground object types. According to the theory of color constancy of natural objects, it gives full play to the visual cognitive advantages of familiar ground objects and significantly improves the multi-scale terrain detail identification ability.

[0103] The present invention optimizes problems such as geometric distortion, light dependence and detail mismatch, and has significant technical advantages in micro-topography analysis, geological disaster risk identification and ecological parameter extraction.

[0104] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims. The information disclosed in the background art part of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or any form of implication that this information constitutes the prior art known to those skilled in the art.

Claims

1. A method for generating a three-dimensional terrain visualization map based on dynamic color matching, characterized in that, Including: Step 1): Obtain a digital elevation model or a digital surface model based on lidar technology, and import the model into a geographic information system processing platform for processing; Step 2): In the slope analysis module of the geographic information system processing platform, input the target digital elevation data raster to generate slope raster data; Step 3): Import the digital elevation data into the spatial visibility analysis module, select the calculation functions of the positive terrain opening degree POS and the negative terrain opening degree NEG, generate POS and NEG data, and import them into the geographic information system processing platform as a new layer; Step 4): Use the raster calculator tool to obtain the ridge-valley index raster data according to the formula RVI = (POS - NEG) / 2; Step 5): Overlay the slope data with the ridge-valley index data layer, set the layer into a red, green pure color or blue-red, cyan-orange color mode according to different land feature characteristics, and adjust through the hard light blending mode to achieve three-dimensional terrain layer rendering; Step 6): Output a visual three-dimensional map to support terrain feature recognition and ecological governance analysis.

2. The method for generating a three-dimensional terrain visualization map based on dynamic color matching according to claim 1, wherein, In the said Step 1), obtain the original elevation data through airborne lidar scanning; perform noise removal, ground point extraction and classification processing on the original data to generate standard DEM / DSM raster data.

3. The method for generating a three-dimensional terrain visualization map based on dynamic color matching according to claim 1, wherein In the said Step 3), when calculating the positive terrain opening degree POS and the negative terrain opening degree NEG, load the DEM data into the RVT module, check the corresponding opening degree analysis function, and generate the positive terrain opening degree POS and the negative terrain opening degree NEG raster data.

4. The method for generating a three-dimensional terrain visualization map based on dynamic color matching according to claim 1, wherein In the said Step 5), the method for setting the layer color mode is: Reclassify the ridge-valley index data, divide the colors according to the range values, and the more range values are set when the elevation difference of the plot area is larger. Usually, two to four elevation range values are set; When the land feature is vegetation or soil, color the slope layer green; When the terrain undulation is small, color the slope layer red; When the land feature is a mountain, adopt a blue-red gradient mode: use red as the highest elevation point value, blue as the lowest elevation point value, and use a blue-red transition color for the middle range value and reduce the brightness; When the land feature is water, adopt a cyan-orange gradient mode: use cyan as the lowest elevation point value, orange as the highest elevation point value, and use a cyan-orange transition color for the middle range value and reduce the brightness; The overlay order of the color / monochrome layer and the slope layer is: Set the transparency of the color gradient / monochrome gradient slope layer to 50%, overlay it on the RVI layer, and adjust the brightness through the hard light blending mode to form a three-dimensional terrain rendering effect.

5. The method for generating a three-dimensional terrain visualization map based on dynamic color matching according to claim 1, wherein In the said Step 6), the method for generating the visual three-dimensional map is: Perform three-dimensional modeling on the rendered terrain data through the three-dimensional visualization module of the geographic information platform to generate a visual three-dimensional map.

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