Data-dependent gradient quantization scheme for the acceleration of volume rendering
Peer‐Timo Bremer, Oliver Kreylos, Bernd Hamann · Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2001
Volume rendering requires the use of gradient information used as surface normal information, for application of lighting models. However, for interactive applications on- the-fly calculation of gradients is too slow. The common solution to this problem is to quantize gradients of trivariate scalar fields and pre-compute a look-up table prior to the application of a volume rendering method. A number of techniques have been proposed for the quantization of normal vectors, but few have been applied to or adapted for the purpose of volume rendering. We describe a new data- dependent method to quantize gradients using an even number of vectors in a table. The quantization scheme we use is based on a tessellation of the unit sphere. This tessellation represents an 'optimally' distributed set of unit normal vectors. Staring with a random tessellation, we optimize the size and distribution of the tiles with a simulated annealing approach.