Fast BTF Texture Modelling | Department of Pattern Recognition

Michal Haindl Jiří Filip

Abstract:

This work presents a fast model-based algorithm for realistic multispectral BTF texture model capable of direct implementation inside the graphical card processing unit. The algorithm starts with surface range-map estimation from one texture image based on shape from shading technique [Frankot,Chellappa 88]. The estimated range-map is finally combined with probabilistic smooth synthetic texture. Synthetic BTF image is rendered according surface range-map for required view and illumination angle.

The presented model offers huge BTF texture compression ration which cannot be achieved by any other sampling-based BTF texture synthesis method (only one range map and about hundred of real numbers have to be stored).
It is possible to generate BTF texture of arbitrary size in case when also the range map is modelled.

GMRF texture model

Firstly the spectral and spatial factorization of an input multispectral texture image is performed. Single orthogonal monospectral components are decomposed into a multi-resolution grid and each resolution data are independently modelled by their dedicated Gaussian Markov random field model (GMRF). We estimate an optimal contextual neighbourhood and parameters for each GMRF. Finally single synthesized monospectral texture pyramids are collapsed into the fine resolution images and using the inverse Karhunen-Loeve transformation we obtain the smooth multispectral texture. Both multispectral and range information is combined in a displacement mapping filter of the rendering hardware.

Results

Original BTF images
light from right	light from top	light from left

Corresponding GMRF smooth synthesis

Results of BTF for measured range-map (laser scaner)
light from right	light from top	light from left	range-map

Results of BTF for estimated range-map (SFS method)
light from right	light from top	light from left	range-map

Corduroy BTF data by courtesy of R. Klein, Bonn University.

		BTF results
Original	Range-map	light from right	light from top	light from left

Reference:

Haindl, M., and J. Filip, "Fast BTF texture modelling", Texture 2003: Proceedings of 3rd Internatinal Workshop on Texture Analysis and Synthesis, Edinburgh, IEEE Press, pp. 47-52, October, 2003.