Overview

In conventional rendering pipelines, complex 3D objects are rendered with triangles that often project to about the size of a pixel. Rasterizing these tiny primitives leads to inefficient operation of triangle based rendering pipelines. Modern scanning devices provide 3D graphics objects with unprecedented geometric and photometric detail. In a conventional approach, triangle meshes are generated from the raw data to render these objects. However, this requires a significant amount of preprocessing. Moreover, it is often necessary to apply mesh reduction strategies for interactive rendering, compromising the quality of the rendered images.

The goal of this thesis is to explore the use of surface elements, or surfels, as rendering primitives. A surfel is a point sample of an object surface that comprises geometric attributes such as position and normal as well as photometric attributes such as a diffuse color. We want to use our technique to directly render scanned objects and other highly complex 3D models. Our research focuses on strategies for discretizing synthetic graphics objects into point-based representations, storing them efficiently and rendering high quality images. We are particularly interested in the aliasing problem arising when generating raster images from point-based objects. We also investigate the generalization of point-based rendering to include surface and volumetric data.

Surfels This project is motivated by the desire to render complex three dimensional objects as efficiently as possible. We developed a rendering pipeline that features a hierarchical data structure, LOD and progressive rendering, and fast texture filtering. Surfel objects offer complex shape, low rendering cost and high image quality, which makes them specifically suited for low-cost, real-time graphics, such as games.

Surface Splatting Surface splatting is a novel technique for high quality rendering of point-based objects. We introduce screen space EWA filtering, which provides anisotropic texture filtering. Moreover, surface splatting facilitates edge-antialiasing and order independent transparency using a modified A-buffer.

EWA Volume Splatting EWA volume splatting is a high quality volume rendering algorithm. It applies the EWA resampling framework to direct volume rendering using a splatting approach, hence avoiding aliasing artifacts. It efficiently handles elliptical reconstruction kernels, which facilitates the visualization of rectilinear and unstructured volume data sets.