Research On Display Technology Of Spatial Scene With Large Data Based On Unity3D

Benefit from the rapid development of unmanned aerial vehicle photography technology and 3D automatic reconstruction technology,the digital model generated by oblique photography 3D reconstruction has many geometric details and real texture,which is a qualitative leap compared with traditional manual modeling in large-scale 3D reconstruction of spatial scenes.However,the high quality of the oblique photography model is supported by massive triangular patches and intricate textures.Loading and displaying such models with large amount of data in the virtual scene will bring a huge burden to the computer graphics performance.Unity3D,as the mainstream 3D game engine today,has a good application in all walks of life due to its excellent 3D model display ability and customizable interactive roaming experience.However,it is difficult for Unity3 D to maintain the fluency of virtual roaming when displaying the large-scale spatial scene model generated by oblique photography 3D reconstruction.In order to solve this problem,a method of displaying spatial scene with large data based on Unity3 D is proposed in this paper.The main research contents are as follows:1.Referring to the file format of the oblique photography 3D model,construct a quadtree forest class to record the information of each node model in the spatial scene of quadtree LOD(Level of Detail)structure.2.Combining quadtree LOD technology with visibility culling technology to dynamically hide or replace the node model in the virtual scene,so as to reduce the graphics cost of meaningless drawing and optimize the rendering speed of the whole scene.3.On the basis of traditional quadtree LOD,an improved LOD method based on image complexity is proposed.The information entropy of 3D model texture is introduced into LOD’s nodal evaluation system as image complexity,thereby making management and replacement of node model by LOD more appropriate.Finally,the experiment is carried out by using the oblique photography model data from the actual production project.By comparing the method proposed in this paper with Unity’s default method of loading a single-level oblique photography 3D model,the results show that the quadtree LOD loading method based on Unity3 D proposed in this paper can greatly reduce the drawing of useless triangular patches and geometric vertices in virtual scenes,and effectively elevate rendering rate while maintain the fineness of spatial scene.The improved LOD algorithm based on image complexity further enhances the effect of LOD,and performs better when displaying areas with complex terrain changes.