Research On Large-scale Terrain Real-time Rendering Method Based On LOD And Viewpoint Prediction

In recent years,the combination of graphics and image technology and computer application technology has grown in depth.Large-scale terrain visualization and the real-time rendering technology derived from it have also been widely used and promoted in various fields,indicating that the technology plays an important role in these fields.Important role.In the related research and application of computer graphics,how to accurately and quickly draw large-scale terrain in real time has always been the focus and difficulty of subject research.Real-time rendering needs to maintain synchronization with static rendering on the integrity of the picture,and at the same time on the drawing speed To approach the speed of static rendering,this is a big challenge for the design of real-time rendering algorithms.In the field of real-time rendering of large-scale terrain,the Level of Detail(LOD)algorithm can better control the rendering efficiency and the balance of rendering effects.The level of detail algorithm can partially simulate the characteristics of the human eye The human eye can't perceive or hardly perceive the characteristics to simplify,and establish different resolution detail models for different terrain areas.Since the simplified terrain area is located in an area that is difficult for the human eye to detect,it is difficult for the naked eye to distinguish the difference between the details before and after the simplification,which satisfies the balance of speed and authenticity in real-time rendering.When performing real-time rendering,each frame needs to recall the original terrain node from memory and transfer the new terrain node into memory.It takes a lot of time to schedule internal and external memory.Therefore,it is necessary to use an appropriate disk scheduling mechanism.The movement trajectory of the current viewpoint predicts the possible position of the viewpoint of the next frame in advance,and loads the required rendering nodes of the next frame into memory in advance,which can reduce the time consumed by internal and external memory scheduling and improve the rendering efficiency.After learning the existing level of detail algorithm and the disk scheduling mechanism of terrain nodes,this paper proposes a multi-control factor LOD algorithm based on a restricted quadtree to improve the existing level of detail algorithm,which can better maintain the real-time rendering process Balance the efficiency and authenticity of rendering images;at the same time,the Hermit interpolation algorithm is applied to the disk scheduling algorithm of terrain nodes,which greatly reduces the time of internal and external terrain data exchange and improves the rendering speed of the system.The main work of this article is as follows:1.In-depth study of the real-time rendering technology of large-scale terrain,study the current academic achievements on this issue,and understand the application results of real-time rendering technology,and at the same time,the principle of LOD of the level of detail algorithm and the object's visibility elimination,Crack elimination technology,disk scheduling algorithm of terrain nodes for further understanding and learning.2.Based on the in-depth study of the existing level-of-detail algorithm,a multi-control factor LOD algorithm based on restricted quadtree(Multi-control factor LOD algorithm based on restricted quadtree)is proposed.The newly added view-related factors not only can improve rendering efficiency,but also increase the authenticity of rendering;at the same time,in the field of view culling,the use of circular enclosing spheres for terrain nodes to remove visibility,compared to using only six sides for the view The calculation process of the shape of the viewing cone and the round surrounding ball to determine whether the terrain node is inside the viewing cone is simpler,and the node visibility judgment can be performed more quickly,thereby improving the rendering efficiency.3.Based on the Hermite interpolation algorithm,a disk scheduling algorithm for terrain nodes is proposed.The algorithm can extrapolate the current position of the viewpoint and the position before the viewpoint,predict the position and perspective of the next frame of the viewpoint,and load the terrain node data to be rendered at the position from the external memory into the memory in advance.The algorithm after the viewpoint prediction can greatly reduce the internal and external memory scheduling time of the terrain node,and avoid the decrease of the rendering frame rate caused by the occupation time of the internal and external memory scheduling of a large number of terrain nodes.