Cosine Lobe Based Relighting from Gradient Illumination Photographs (bibtex)
by Graham Fyffe, Cyrus A. Wilson, Paul Debevec
Abstract:
We present an image-based method for relighting a scene by analytically fitting a cosine lobe to the reflectance function at each pixel, based on gradient illumination pho- tographs. Realistic relighting results for many materials are obtained using a single per-pixel cosine lobe obtained from just two color photographs: one under uniform white illumi- nation and the other under colored gradient illumination. For materials with wavelength-dependent scattering, a better fit can be obtained using independent cosine lobes for the red, green, and blue channels, obtained from three monochromatic gradient illumination conditions instead of the colored gradient condition. We explore two cosine lobe reflectance functions, both of which allow an analytic fit to the gradient conditions. One is non-zero over half the sphere of lighting directions, which works well for diffuse and specular materials, but fails for materials with broader scattering such as fur. The other is non-zero everywhere, which works well for broadly scattering materials and still produces visually plausible results for diffuse and specular materials. Additionally, we estimate scene geometry from the photometric normals to produce hard shadows cast by the geometry, while still reconstructing the input photographs exactly.
Reference:
Cosine Lobe Based Relighting from Gradient Illumination Photographs (Graham Fyffe, Cyrus A. Wilson, Paul Debevec), In Conference on Visual Media Production, 2009.
Bibtex Entry:
@inproceedings{fyffe_cosine_2009,
	address = {London, UK},
	title = {Cosine {Lobe} {Based} {Relighting} from {Gradient} {Illumination} {Photographs}},
	url = {http://www.ict.usc.edu/pubs/Cosine%20Lobe%20Based%20Relighting%20from%20Gradient%20Illumination%20Photographs.pdf},
	abstract = {We present an image-based method for relighting a scene by analytically fitting a cosine lobe to the reflectance function at each pixel, based on gradient illumination pho- tographs. Realistic relighting results for many materials are obtained using a single per-pixel cosine lobe obtained from just two color photographs: one under uniform white illumi- nation and the other under colored gradient illumination. For materials with wavelength-dependent scattering, a better fit can be obtained using independent cosine lobes for the red, green, and blue channels, obtained from three monochromatic gradient illumination conditions instead of the colored gradient condition. We explore two cosine lobe reflectance functions, both of which allow an analytic fit to the gradient conditions. One is non-zero over half the sphere of lighting directions, which works well for diffuse and specular materials, but fails for materials with broader scattering such as fur. The other is non-zero everywhere, which works well for broadly scattering materials and still produces visually plausible results for diffuse and specular materials. Additionally, we estimate scene geometry from the photometric normals to produce hard shadows cast by the geometry, while still reconstructing the input photographs exactly.},
	booktitle = {Conference on {Visual} {Media} {Production}},
	author = {Fyffe, Graham and Wilson, Cyrus A. and Debevec, Paul},
	month = nov,
	year = {2009},
	keywords = {Graphics}
}
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