Research On Simplification Of Building LOD Based On Outline Extraction

Three-dimensional building models can be applied in many scenarios,such as urban landscapes,three-dimensional map navigation,geographic information systems,and so on.The application of three-dimensional building models can greatly enhance people's immersion and enrich their sensory experience.With the development of modern 3D model data acquisition methods such as laser scanning,oblique aerial photography,and 3D modeling software,the details of architectural models are also developing towards high precision.This has also led to the increasing storage space and data volume of architectural models.Increasingly huge.The current software and hardware performance of computers is difficult to process large-scale building models in real time,which limits the application scenarios of building models on a certain level,especially for large-scale building models,such as digital cities.Considering that the 3D building model is the main component of many application scenarios,it is necessary to simplify the 3D building model to achieve the purpose of improving model transmission efficiency and rendering efficiency.By studying the method of simplification of the level of detail of the threedimensional building model,a multi-resolution building model is established to effectively reduce the data volume of the building model.This also puts forward new goals for computer visualization,how to reduce the rendering load of graphics as much as possible on the premise of ensuring visual continuity and high-resolution models.This article focuses on three-dimensional building models,and studies how to reduce the rendering load and improve rendering efficiency as much as possible under the premise of ensuring high-precision models.The main research contents are as follows:(1)A simple and efficient outline extraction algorithm is proposed.The building model can be decomposed into two parts,one is the external details of the building,and the other is the internal details of the building.Generally speaking,the triangles of the internal details of the building occupy a relatively high proportion.Less total.When the point of view is outside the building,you can see the building's outline,only when you enter the building,you can see the building's internal details.Based on these two characteristics,this paper studies an efficient algorithm for extracting the outline of a building.When the distance is far from the building,replacing the original building model with the outline will greatly improve rendering efficiency and reduce rendering load.This is the first meaning of the simplified method in this article.(2)Construct level of detail of building model.According to a common sense,when the viewpoint is far away from the building,you see a rough outline;when the viewpoint is closer to the building,you see a fine outline;when the viewpoint enters the building,you see Details of the building interior.Therefore,level of detail of models can be constructed.For example,LOD0 represents the original building model,LOD1 represents the fine outer contour,and LOD2 represents the rough outline...Building a building-level detail model can further improve rendering efficiency while maintaining appearance features.This is the second meaning of the simplified method in this paper.(3)Unified the standard for LOD generation and switching.The generation of LOD depends on the simplified method of the building model.After the generation of the LOD is completed,a series of standards are defined in the program to define the LOD switching criteria.Equivalent to the generation of the LOD and the switching of the LOD use different standards,which is not good for the application of the LOD,so it is necessary to unify the standards for the generation and switching of the LOD to reduce the threshold for the use of the LOD in the building.The experimental results show that the simplification method in this paper can effectively simplify the building model and build the building-level detail model.The loading of the building-level detail model can not only greatly improve the rendering efficiency without affecting the visual experience,but also maintain high-resolution building details.The validity of the simplified method of 3D building model is further verified.