Space-Optimized Texture Maps And Extension To Volume Warping
Dr. Laurent Balmelli
Friday February 7, 2003
Host: Denis Zorin, firstname.lastname@example.org, 212-998-3405
Texture mapping is a common operation to increase the realism of three-dimensional meshes at low cost. We propose a new texture optimization algorithm based on the reduction of the physical space allotted to the texture image. Our algorithm optimizes the use of texture space by computing a warping function for the image and new texture coordinates. Neither the mesh geometry nor its connectivity are modified by the optimization. Our method uniformly distributes frequency content of the image in the spatial domain. In other words, the image is stretched in high frequency areas, whereas low frequency regions are shrunk. We also take into account distortions introduced by the mapping onto the model geometry in this process.
The resulting image can be resampled at lower rate while preserving its original details. The unwarping is performed by the texture mapping function. Hence, the space-optimized texture is stored as-is in texture memory and is fully supported by current graphics hardware. We present several examples showing that our method significantly decreases texture memory usage without noticeable loss in visual quality.
We recently extended our warping technique [Vis2002] to intensity function defined on the cube, e.g. volume dataset. We use our method to perform automatic adaptive isosurface extraction without the use of any hierarchical datastructure such as octrees, etc. An isosurface is extracted from a warped volume, then the resulting set of vertices is unwarped such that the surface is rescaled to its initial proportions. We demonstrate the usability of the technique with several well known models.