A 3D Visualization Virtual Scene Modeling Method in UAV Virtual Simulation

Abstract

The present invention discloses a method for three-dimensional visual virtual scene modeling in UAV virtual simulation, belonging to the field of visual simulation technology. According to the principle of similarity normalization of characteristic attributes, buildings are divided into landmark buildings and non-landmark buildings. The landmark buildings are finely modeled using 3D animation production software, and the vector grids of landmark buildings are extracted from remote sensing images. Then, the non-landmark buildings are modeled on a large scale using 3D visualization modeling software, and the landmark building models and non-landmark building models are integrally and diversely fused in the Unreal Engine software. The diverse fusion modeling of the present invention greatly improves the modeling speed while ensuring the modeling quality, realizes the three-dimensional mapping of the real scene through remote sensing images, and the established model has good immersion and interaction performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of visual simulation, and particularly relates to a method for modeling a three-dimensional visual virtual scene in unmanned aerial vehicle (UAV) virtual simulation. Background Art

[0002] Visual simulation is an immersive interactive technology based on computer graphics that supports the visual display of information. Since flight visual simulation technology can combine the three-dimensional virtual model of a UAV, the simulation process, and the simulation data, and simultaneously perform visual output and display, it has been highly favored by scholars at home and abroad. Currently, mainstream flight visual simulation software such as Creator, X-Plane, and Flight Gear have more or less problems such as low efficiency in three-dimensional virtual scene modeling, and poor immersion, interactivity, and authenticity in the simulation process.

[0003] Most early UAV visual simulation systems were based on two-dimensional map data or digital graphics, making it difficult for researchers to detect the relevant characteristics hidden in the data and unable to intuitively understand the flight status of the UAV. Since the 21st century, the development of 3D technology has given rise to the emergence of a number of game engines. At the same time, 3D game engines provide a complete set of solutions for game or visual development, which has strongly promoted the development of digital twin three-dimensional visual scene modeling technology. Currently, well-known 3D game engines in the industry mainly include ORGE, Unity 3D, Unreal Engine 4, etc. Shangguan Youbai developed a port visual simulation demonstration system based on OGRE. This system mainly simulates the operating conditions of port equipment and the impact of different climates on the port system, and has made good progress in terms of visual immersion. Li Qing constructed a flight visual simulation platform based on the Unity 3D game engine to reproduce the operating scenes of aircraft carriers and aircraft. This platform has a realistic display effect and good immersion, but the scene modeling is complex and the efficiency is low. Summary of the Invention

[0004] In order to overcome the defects of traditional UAV visual simulation methods, such as unsatisfactory immersion and interactive effects, complex scene construction, and low modeling efficiency, the present invention provides a method for modeling a three-dimensional visual virtual scene in UAV virtual simulation, which performs multi-element fusion modeling, greatly improves the modeling speed while ensuring the modeling quality, realizes the three-dimensional mapping of the real scene through remote sensing images, and the established model has good immersion and interactive performance.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a three-dimensional visualization virtual scene modeling method in UAV virtual simulation, including: dividing buildings into landmark buildings and non-landmark buildings according to the principle of similarity normalization of characteristic attributes, using 3D animation production software to perform refined modeling on landmark buildings, and extracting the vector grid of landmark buildings from remote sensing images; then using 3D visualization modeling software to perform large-scale modeling on non-landmark buildings, and integrating and fusing the landmark building model and the non-landmark building model in Unreal Engine software.

[0006] As a further implementation of the present invention, the use of 3D animation production software to perform refined modeling on landmark buildings includes: importing the CAD data of landmark buildings into 3ds Max, after capturing, extruding, chamfering, and inserting processing, then using the rectangle tool to outline the edges; according to the height and structure of the top surface of the landmark building, adding different material and texture elements in different areas of the model.

[0007] As a further implementation of the present invention, during the refined modeling process of landmark buildings, the invisible inner surfaces in the splicing areas of connected buildings are removed, and for horizontal and vertical structures, the number of Boolean operations is minimized.

[0008] As a further implementation of the present invention, the use of 3D visualization modeling software to perform large-scale modeling on non-landmark buildings includes: using City Engine to perform large-scale vector data modeling, taking the bottom of the building as the standard, using the FAME-Net network to train the aerial remote sensing image building data set, and extracting the vector data of non-landmark buildings.

[0009] As a further implementation of the present invention, during the large-scale modeling process of non-landmark buildings, the building is split into multiple structural components, large-scale CGA rules are constructed according to the building structure, height, and color, and texture mapping is performed on the structural components of the building using the texture mapping function.

[0010] As a further embodiment of the present invention, the integrated multi - element fusion of the landmark building model and the non - landmark building model in the Unreal Engine software includes: importing DEM digital elevation data in the virtual engine UE4 for terrain data design, using the GDEMV2 elevation dataset as the original data source, performing interpolation and noise reduction processing on the original data, and then importing the terrain data into Global Mapper for three - dimensional expansion to obtain a terrain elevation map file in hfz format; setting the resolution and data range in World Machine according to the width and height of the elevation map to obtain an elevation map file in RAW16 format compatible with UE4; importing the RAW16 - format height map in UE4, selecting the material corresponding to the remote sensing image to create a three - dimensional terrain, and importing the constructed landmark building model and non - landmark building model into UE4 in the same proportion and placing them on the constructed three - dimensional terrain.

[0011] The beneficial effects of the present invention include:

[0012] 1. Design a multi - element fusion modeling method, which greatly improves the modeling speed while ensuring the modeling quality;

[0013] 2. Realize the three - dimensional mapping of the real scene through remote sensing images, and the established model has good immersion and interactive performance. Description of the Drawings

[0014] Figure 1 is the flowchart of the modeling method of the present invention;

[0015] Figure 2 is the schematic diagram of refined modeling in Embodiment 1 of the present invention;

[0016] Figure 3 is the schematic diagram of large - scale modeling vector grid data in Embodiment 1 of the present invention;

[0017] Figure 4 is the partial CGA code diagram in Embodiment 1 of the present invention;

[0018] Figure 5 is the schematic diagram of campus three - dimensional virtual scene modeling in Embodiment 1 of the present invention;

[0019] Figure 6 is the campus three - dimensional scene diagram in Embodiment 1 of the present invention;

[0020] Figure 7 is the virtual scene immersion and interactive test diagram in Embodiment 2 of the present invention. Detailed Embodiments

[0021] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0022] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or component 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. In addition, the terms "first", "second", "third" are only used to distinguish components and cannot be construed as indicating or implying relative importance.

[0023] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0024] Embodiment 1

[0025] Building a virtual world that can map the physical world is the cornerstone of UAV visual simulation. For this reason, this embodiment constructs a twin virtual model of a real flight scene. The most crucial element in the construction of the virtual scene is the building. Using 3dsMax to construct simulation objects can obtain relatively realistic effects, but the modeling speed is too slow. For this reason, this embodiment proposes a three-dimensional visualization virtual scene modeling method of multi-element fusion. According to the principle of similarity normalization of building characteristic attributes, buildings are divided into landmark buildings (such as libraries, stadiums) and non-landmark buildings (such as dormitory buildings, teaching buildings). Use 3ds Max to carry out refined modeling of landmark buildings, extract the vector grid of buildings from remote sensing images, and then use City Engine software to carry out large-scale modeling of non-landmark buildings, and integrate the models of 3ds Max and City Engine in UE4 for multi-element integration. The modeling process is as Figure 1 shown.

[0026] 1. Refined modeling

[0027] First, carry out refined modeling on the important buildings in the scene. Taking the library of N campus as an example, import its CAD data into 3ds Max, and after operations such as snapping, extrusion, chamfering, and insertion, use the rectangle tool to outline the edge of the wall. Secondly, according to the height and structure of the top surface of the building, add different materials and texture elements in different areas of the model to increase the texture and realism of the building body, as Figure 2 shown.

[0028] In order to reduce the redundancy and complexity of the model and improve the running speed of the model, this embodiment proposes a method for optimizing the number of surfaces. In the modeling process, the invisible inner surfaces in the splicing area of ​​the connected buildings are removed to reduce the generation of invalid surfaces and avoid the redundancy generated by a large number of duplicated structured models. For horizontal and vertical structures, the number of Boolean operations is minimized to reduce the complexity of the model. In order to minimize the number of models, the fine threshold in the model modifier is optimized to improve the running speed of the model while ensuring the authenticity of the building.

[0029] 2. Large-scale modeling

[0030] Large-scale modeling mainly solves the modeling of non-sign buildings, trees and roads. In order to improve the modeling speed, this embodiment uses City Engine to perform large-scale vector data modeling based on the rule method. Traditional oblique photography technology uses the building roof as the standard vector data extraction method. The existing building tilt, displacement and missing problems will lead to modeling deviations. Figure 3 As shown, this embodiment uses the bottom of the building as the standard and uses the FAME-Net network to train the aerial remote sensing image building data set to avoid the extraction bias of the traditional method and extract the vector data of the building.

[0031] CGA (Computer Generated Architecture) rules are the core of building a large-scale modeling method, which focuses on modeling speed and efficiency, and can ignore some detailed information of buildings. To this end, modeling rules are written according to the structural type, floor height, and roof color of the building, and the corresponding type of buildings are generated in large quantities and quickly. The details of the building are related to the binding force of the rules. The more rules there are, the more complete the model details are.

[0032] In this embodiment, taking the N campus scenario as an example, in order to establish the CGA rule, it is necessary to find out the relationship between the number of floors and height of the building. The heights and numbers of floors of some buildings in the study area are measured, and Table 2 is drawn.

[0033] Table 2 Building height and number of floors

[0034]

[0035] According to Table 2, the relationship between building height and number of floors is obtained as shown in the following formula:

[0036] H=3.46N+0.69 (6)

[0037] The building is specifically divided into small structural components, and a large-scale rule is constructed according to the building structure, floor height and color. The texture mapping function is used to map the doors, windows, roofs and exterior walls of the building. Some CGA codes are as follows Figure 4 shown.

[0038] In addition, except for the building models, the flowers, plants, trees, street lights, and roads are built using existing rules to generate the 3D virtual scene of N Campus as Figure 5 shown.

[0039] 3. Model Multi-Fusion

[0040] To improve the immersion and interactivity of the simulation, DEM (Digital Elevation Map) digital elevation data is imported in UE4 for the design of uneven terrain. In this embodiment, the GDEMV2 elevation dataset is used as the original data source. However, the massive DEM data will affect the running speed of the subsequent virtual scene, and at the same time, the data volumes describing flat and complex terrain areas are different, so the original DEM data needs to be processed. For this reason, this embodiment performs interpolation and noise reduction processing on the original data to improve data utilization. Then, the terrain data is imported into Global Mapper for 3D expansion to obtain a terrain file in hfz format. After that, according to the width and height of the elevation map, the resolution and data range are set in World Machine to obtain a RAW16 format height map file compatible with UE4. For the multi-fusion of the scene in UE4, the RAW16 format height map is imported, and the material corresponding to the remote sensing image is selected to create a real 3D terrain with unevenness. The buildings constructed by 3ds Max and CityEngine are imported into UE4 in the same proportion and placed on the constructed 3D terrain. To solve the dynamic interaction between models, collision settings are added between different objects to realize the transformation of the scene from 2D static to 3D dynamic, as Figure 6 shown.

[0041] Example 2

[0042] Virtual Scene Immersion and Interaction Performance Test:

[0043] To conduct the immersion and interaction tests of the virtual scene, a drone digital model is made to fly autonomously in the Figure 6 constructed main entrance scene of N Campus, as Figure 7 shown. Since the construction of the 3D virtual scene is a twin mapping of the real scene, the mountains and terrain are consistent with the real environment, and elements such as trees and red flags in the scene will also move with the wind, and the whole scene has good immersion. When the drone is at the Figure 7 circle position in the virtual scene, the surrounding environment information sensed by the fisheye camera in real time is shown in the small box in the lower left corner. At this time, the drone senses an obstacle flag, and due to the collision settings in the scene, it will execute the action of avoiding obstacles at that time, and has good interactivity with the environment, which can provide technical support for performance tests such as 3D surveying and obstacle avoidance.

[0044] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to exhaustively list all implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A method for three-dimensional visualization virtual scene modeling in UAV virtual simulation, characterized in that, it includes: Dividing buildings into landmark buildings and non-landmark buildings according to the principle of similarity and normalization of characteristic attributes, using 3D animation production software to carry out refined modeling of landmark buildings, and extracting vector grids of landmark buildings from remote sensing images; Then using 3D visualization modeling software to carry out large-scale modeling of non-landmark buildings, and carrying out integrated multi-element fusion of landmark building models and non-landmark building models in Unreal Engine software; The using 3D animation production software to carry out refined modeling of landmark buildings includes: importing CAD data of landmark buildings into 3ds Max, after operations such as snapping, extrusion, chamfering, and insertion, then using the rectangle tool to outline the edges; according to the height and structure of the top surface of the landmark building, adding different material and texture elements in different areas of the model; The using 3D visualization modeling software to carry out large-scale modeling of non-landmark buildings includes: using CityEngine to carry out large-scale vector data modeling, taking the bottom of the building as the standard, using the FAME-Net network to train the aerial remote sensing image building data set, and extracting vector data of non-landmark buildings; The carrying out integrated multi-element fusion of landmark building models and non-landmark building models in Unreal Engine software includes: importing DEM digital elevation data in the virtual engine UE4 for terrain data design, using the GDEMV2 elevation data set as the original data source, carrying out interpolation and noise reduction processing on the original data, then importing the terrain data into GlobalMapper for three-dimensional expansion to obtain a terrain elevation map file in hfz format; according to the width and height of the elevation map, setting the resolution and data range in WorldMachine to obtain an elevation map file in RAW16 format compatible with UE4; importing the RAW16 format height map in UE4, selecting the material corresponding to the remote sensing image to create a three-dimensional terrain, and importing the constructed landmark building model and non-landmark building model into UE4 in the same proportion and placing them on the constructed three-dimensional terrain.

2. A method for three-dimensional visualization virtual scene modeling in UAV virtual simulation according to claim 1, characterized in that, During the refined modeling of landmark buildings, removing the invisible inner surfaces in the splicing areas of connected buildings, and minimizing the number of Boolean operations for horizontal and vertical structures.

3. A method for three-dimensional visualization virtual scene modeling in UAV virtual simulation according to claim 1, characterized in that, During the large-scale modeling of non-landmark buildings, splitting the buildings into multiple structural components, constructing large-scale CGA rules according to the building structure, height and color, and using texture mapping functions to perform texture mapping on the structural components of the buildings.

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