Tesselation of Trimmed NURBS Surfaces using Multipass Shader Algorithms on the GPU

Abstract

In Computer Aided Design (CAD) 3D objects are often represented in form of trimmed NURBS surfaces. However, the rendering of NURBS surfaces is not directly supported by common graphics hardware. Special tessellation and trimming algorithms are required to convert the parametric NURBS surfaces into a polygonized form so that the GPU can properly render the NURBS surfaces.

This thesis describes the implementation and further analysis on a fast and efficient GPU based rendering algorithm for trimmed NURBS surfaces presented by Michael Guthe. The algorithm uses texture based trimming methods and is using the GPU to evaluate NUBRS surfaces. To further optimize the algorithm, a detailed analysis of the algorithm is shown. The bottlenecks of the algorithm are illustrated and further improvements to counter the found bottlenecks are presented.

The algorithm is evaluated and reviewed to identify, if it can be used to visualize high detailed aircraft models that are created by the geometry library TiGL. Compared to conventional algorithms, the presented tessellation and trimming algorithm could improve the performance and visual appearance of rendered aircraft models.