GPU-based trimming and tessellation of NURBS and T-Spline surfaces

In: ACM Transactions on Graphics (Aug. 2005), 24:3(1016-1023)
Präsentiert: SIGGRAPH 2005
 

Abstract

As there is no hardware support neither for rendering trimmed NURBS - the standard surface representation in CAD - nor for T-Spline surfaces the usability of existing rendering APIs like OpenGL, where a run-time tessellation is performed on the CPU, is limited to simple scenes. Due to the irregular mesh data structures required for trimming no algorithms exists that exploit the GPU for tessellation. Therefore, recent approaches perform a pretessellation and use level-of-detail techniques. In contrast to a simple API these methods require tedious preparation of the models before rendering and hinder interactive editing. Furthermore, due to the tremendous amount of triangle data smooth zoom-ins from long shot to close-up are not possible. In this paper we show how the trimming region can be defined by a trim-texture that is dynamically adapted to the required resolution and allows for an efficient trimming of surfaces on the GPU. Combining this new method with GPU-based tessellation of cubic rational surfaces allows a new rendering algorithm for arbitrary trimmed NURBS and T-Spline surfaces with prescribed error in screen space on the GPU. The performance exceeds current CPU-based techniques by a factor of up to 1000 and makes real-time visualization of real-world trimmed NURBS and T-Spline models possible on consumer-level graphics cards.

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Bibtex

@ARTICLE{guthe-2005-gpu-based,
      author = {Guthe, Michael and Bal{\'a}zs, {\'A}kos and Klein, Reinhard},
       pages = {1016--1023},
       title = {GPU-based trimming and tessellation of NURBS and T-Spline surfaces},
     journal = {ACM Transactions on Graphics},
      volume = {24},
      number = {3},
        year = {2005},
       month = aug,
    abstract = {As there is no hardware support neither for rendering trimmed NURBS - the standard surface
                representation in CAD - nor for T-Spline surfaces the usability of existing rendering APIs like
                OpenGL, where a run-time tessellation is performed on the CPU, is limited to simple scenes. Due to
                the irregular mesh data structures required for trimming no algorithms exists that exploit the GPU
                for tessellation. Therefore, recent approaches perform a pretessellation and use level-of-detail
                techniques. In contrast to a simple API these methods require tedious preparation of the models
                before rendering and hinder interactive editing. Furthermore, due to the tremendous amount of
                triangle data smooth zoom-ins from long shot to close-up are not possible. In this paper we show how
                the trimming region can be defined by a trim-texture that is dynamically adapted to the required
                resolution and allows for an efficient trimming of surfaces on the GPU. Combining this new method
                with
                GPU-based tessellation of cubic rational surfaces allows a new rendering algorithm for arbitrary
                trimmed NURBS and T-Spline surfaces with prescribed error in screen space on the GPU. The
                performance exceeds current CPU-based techniques by a factor of up to 1000 and makes real-time
                visualization of real-world trimmed
                NURBS and T-Spline models possible on consumer-level graphics cards.},
  conference = {SIGGRAPH 2005}
}