Development of CG Technologies Based on the Geometric Model Represented by a Set of Points

在这项研究中，我们发展了几种与一组点作为基本几何模型相关的CG技术：建模和绘制技术，一组点和另一模型之间的相互转换技术，特别是多边形模型。将以下模型视为一组点：由深度扫描仪和DEM(数字高程模型)获得的2D标量网格场，主要由粒子模拟获得的医学图像、体素空间、3D纹理和点云等3D标量网格场。绘制技术的方法分为：对由一组点转换成的多边形模型应用传统的多边形绘制，对一组点直接应用基于点的绘制，对由另一类模型转换的一组点应用基于点的绘制。特别是，后一种方法被认为是一种最有可能具有LOD(层次细节)和抗锯齿能力的方法，对于绘制包括大量复杂对象(如树木)的广泛自然景观而言，是必不可少的。在本研究中，我们开发了以下技术来处理一组点：1.深度图像建模技术(1.1)整合多个深度图像的位置匹配算法(1.2)使点分布均匀的算法(1.3)使用遗传算法使几何基元适应深度图像的算法2.体素空间的渲染算法(2.1)平滑法线的边缘保持算法3.从一组点生成表面的算法(3.1)使用速度场的水平集算法(3.2)寻找多边形壳的递归算法4.基于点的绘制(4.1)用于模拟一阶散射的基于点的绘制(4.2)用于将多边形模型转换为3D纹理的算法(4.3)用于将多边形模型转换为点云的算法

In this study, we developed several kinds of CG techniques related to a set of points as a fundamental geometric model: modeling and rendering techniques, mutual transformation techniques among a set of points and another model, especially a polygon model. The following models are regarded as a set of points : 2D scalar grid fields such as depth images obtained by a range scanner and DEM(Digital Elevation Model), 3D scalar grid field such as medical images, voxel spaces, 3D textures and point clouds mainly obtained by a particle simulation. The approaches of rendering techniques are classified into those: to apply a conventional polygon rendering to a polygon model transformed from a set of point, to apply point-based rendering directly to a set of points, and to apply point-based rendering to a set of points transformed from another type of model. Especially, the latter approach is expected as a most possible method having the abilities of LOD(Level Of Detail) and anti-aliasing indispensable to render broad natural landscape sceneries including huge amount of complex objects like trees.In this study, we developed the following techniques for handling a set of points1.Modeling techniques for depth images(1.1)Position matching algorithms for integrating multiple depth images(1.2)Algorithms for making the distribution of points uniform(1.3)An algorithm for adapting geometric primitive to depth image using Genetic Algorithm2.Rendering algorithm for voxel spaces(2.1)An edge preserving algorithm for smoothing normal3.Surface generation algorithms from a set of points(3.1)A level-set algorithm using velocity fields(3.2)A recursive algorithm for finding a polygon hull4.Point-based rendering(4.1)Point-based rendering for simulating first order scattering(4.2)An algorithm for transforming a polygon model to a 3D texture(4.3)An algorithm for transforming a polygon model to a point cloud