Research On View-dependent Terrain Model Simplification And Precision Evaluation

Precision is an important guideline to evaluate the terrain model and the visual precision and mathematic precision which adequately take human visual apperception discipline into consideration, have been the important measures to weigh the terrain model. So, this text is based on three typical simplification arithmetic and investigates the predigested arithmetic and precision evaluation of view-dependent terrain LOD model. The main content and innovation are listed as following:Firstly, introduces the research of view-dependent terrain model simplification arithmetic at home and abroad, summarizes the measured guidelines and controlling methods of simplification errors, analyses and concludes the factors which influence the expression of model precision and the factors and characteristics which influence the effect of human's visual perception. On this base, bounds the concept of the ration of model simplification and model simplification errors, presents the resolution concept of view-dependent LOD model and fixed quantum expressions.Secondly, based on quadtree simplification arithmetic, studies the stabilization output rate, and two optimizing projects to improve the View Frustum Culling. Validates the arithmetic with three kinds of terrain data and analyses the simplification rate of viewport distance and model and the whole errors and the variety discipline between different scale DEM data, draws up the relevant fixed quantum formula, provides some useful studying thoughts and applications for view-dependent model simplification and precision evaluation based on quadtree.Thirdly, based on ROAM arithmetic, sets up terrain Roughness adjusting gene and bring them into calculating the radial of nested ball so as to help the arithmetic show the detailed local characteristic of terrain with less triangular numbers on the same simplified effect conditions. Studies and analyses the variety discipline between the viewport distance and model and the whole errors on three physiognomy conditions, and draws up the fixed quantum formula.Fourthly, puts forwards a strategy of the parted disposal of the terrain TIN structural data and selected simplification of terrain based on the center of view Frustum, improves real time alternate capability and accords more with of human's visual perception discipline at the same time. Studies and analyses the variety discipline between the viewport distance and model and the whole errors on the condition of different threshold value of errors, and draws up the fixed quantum formula, provides the useful tools for precision evaluation of the view-dependent terrain TIN model.