Point-based Rendering Technology Research And Application,

Along with research and application unceasingly thorough, the scene of rendering became more and more complex, and the request of rendering speed also became more and more high. Though the traditional Geometry-Based Rendering can produce high quality images, but as a result of its own limitation, it faced great challenge in the aspect of real-time rendering. Many researchers have launched thorough and extensive research in the field of real-time rendering, and proposed many new ideas. One of them is the Point-Based Rendering technology, which received the enormous attention with the great progress of three dimensional scanning technology in the recent years. Point-Based Rendering uses discrete and crowded point cloud to represent the surface of model, and it's goal is to reconstruct a continuous and equivalent surface from the point cloud. The practice proved that for models with very complex geometry or complex illumination detail, Point-Based Rendering brings both higher efficiency and better result.This article does the work mainly includes following several aspects:1. The acquisition of data. This thesis reconstructs the three-dimensional grid model of organ from a series of medical CT films by using Marching Cubes algorithm, discusses the problems of Marching Cubes algorithms, and achieves the Asymptotic Decider which is used to resolve the ambiguity of Marching Cubes algorithm.2. Rendering techniques based on Hierarchical Surface Fragments (HSF). Based on the data of rendering, a novel concise representation with dynamical level of detail as well as the corresponding rendering algorithm is presented. A surface fragment is an irregular sampled surface region. A HSF model is comprised of a great number of surface fragments, which are organized in a hierarchical structure by distance scale. During the process of rendering, we use the projected size of surface fragments as the scale of LOD, use the z-delta-buffer and per pixel normalization method to alleviate the visual artifacts.3. Programmable graphics hardware to accelerate the rendering of surfacefragments. This thesis analyzes the main problem existing in hardware acceleration, achieves the integration of surface fragments and the per pixel normalization in three passes, and finally implements the whole rendering process by NVidia's GPU rendering program languages Cg.