EC project no. IST-2001-34744 RealReflect
 
Fast BTF Texture Modelling
 
Michal Haindl     Jiri Filip
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


    Further information can be found in the papers:
    Haindl, M. - Filip, J.
    Fast BTF Texture Modelling
    In: Proceedings Texture 2003, The 3rd international workshop
    on texture analysis and synthesis, Nice 2003,
    M.Chantler Ed.,ISBN 1-904410-11-1,Heriot-Watt University
    pp. 47 - 52. 

    


    

    

    




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