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International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision
(WSCG 2014)
Locally Adaptive Products for Genuine Spherical Harmonic Lighting
    Joo Ho Lee Min H. Kim    
    KAIST, Korea    
  Comparison of rendering between full SH lighting and our locally adaptive approach. Our approach achieves real-time performance (higher than 15 fps.) with genuine SH lighting around level 10 (121 coefficients). Our rendered image is plausibly comparable to the calculation of full-order coefficients while, for instance, the peak signal-to-noise ratio (PSNR) between the two images is 41.73.  
  Precomputed radiance transfer techniques have been broadly used for supporting complex illumination effects on diffuse and glossy objects. Although working with the wavelet domain is efficient in handling all-frequency illumination, the spherical harmonics domain is more convenient for interactively changing lights and views on the fly due to the rotational invariant nature of the spherical harmonic domain. For interactive lighting, however, the number of coefficients must be limited and the high orders of coefficients have to be eliminated. Therefore spherical harmonic lighting has been preferred and practiced only for interactive soft-diffuse lighting. In this paper, we propose a simple but practical filtering solution using locally adaptive products of high-order harmonic coefficients within the genuine spherical harmonic lighting framework. Our approach works out on the fly in two-fold. We first conduct multi-level filtering on vertices in order to determine regions of interests, where the high orders of harmonics are necessary for high frequency lighting. The initially determined regions of interests are then refined through filling in the incomplete regions by traveling the neighboring vertices. Even not relying on graphics hardware, the proposed method allows to compute high order products of spherical harmonic lighting for both diffuse and specular lighting.
author = {Joo Ho Lee and Min H. Kim},
title = {Locally Adaptive Products for Genuine Spherical Harmonic Lighting},
booktitle = {Proc. of WSCG 2014 (International Conference in Central Europe
on Computer Graphics, Visualization and Computer Vision)},
year = {2014},
pages = {27-–36},
address = {Plzen, Czech Republic},
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