Real-Time Display Of Large-Scale 3D Terrain Based On VSD And LOD Algorithms

Visualization of terrain information is playing a key role in many applications such as geographic information system, simulation system, visual reality and 3D games, etc. With the rapid development of remote sense, satellite technology and computer technology, people expect to investigate or view larger terrain regions with finer precision, which inevitably leads to the real-time rendering of huge terrain dataset.This thesis focuses on the theoretical and methodological studies in several subtopics: VSD (Visible-Surface Detection) and LOD (Level of Detail) of 3D terrain visualization and rendering. These studies are based on lots of advanced results of 3D computer graphics, scientific computation visualization and virtual reality. And the principal contents of this thesis are as follow:Some application backgrounds of the real-time rendering of large-scale terrain data set are introduced. Two fundamental strategies to accelerate the rendering procedure are pointed out, which are VSD algorithm and LOD algorithm. Main resolutions of terrain rendering presented in recent publications are summarized.VSD is introduced in this thesis, which is a main way of real-time rendering of huge terrain dataset, including back face culling, frustum culling and occlusion culling. The characteristics and classes of level of detail are described, as well as a series of related issues. The application with level of detail in large-scale terrain rendering is discussed and a series of algorithms about terrain multi-resolution modeling in recent years are enumerated and discussed. Then a novel method for real-time mufti-resolution modeling is proposed. In order to guarantee the precision of the mufti-resolution model effectively, conservative estimation of the projected error in screen-space criterion which is used to choose an appropriate level of detail, is used as which can stored and computed efficiently.A proposal for large-scale terrain real-time display is proposed. Within this proposal, the VSD and LOD are presented efficiently. The integrate texture mipmap and lightening are also used to obtain higher rendering quality and efficiency.