IS = { zkontrolovano 27 Jan 2009 },
  UPDATE  = { 2008-12-29 },
  author =	 {Drbohlav, Ond{\v r}ej and Chantler, Mike},
  title =	 {Can Two Specular Pixels Calibrate Photometric
  booktitle =	 {Proceedings of the IEEE International Conference on
                  Computer Vision (ICCV)},
  publisher =	 {IEEE Computer Society Press},
  address =	 {Los Alamitos, USA},
  isbn =	 {0-7695-2334-X},
  book_pages =	 {1876},
  editor =	 {Ma, Songde and Shum, Heung-Yeung},
  volume =	 {II},
  pages =	 {1850-1857},
  book_pages =	 {1876},
  year =         {2005},
  annote = {Lambertian photometric stereo with unknown light source
    parameters is ambiguous. Provided that the object imaged
    constitutes a surface, the ambiguity is represented by the group
    of Generalised Bas-Relief (GBR) transformations. We show that this
    ambiguity is resolved when specular reflection is present in two
    images taken under two different light source directions. We
    identify all configurations of the two directional lights which
    are singular and show that they can easily be tested for. While
    previous work used optimisation algorithms to apply the
    constraints implied by the specular reflectance component, we have
    developed a linear algorithm to achieve this goal. Our theory can
    be utilised to construct fast algorithms for automatic
    reconstruction of smooth glossy surfaces.},
project     = { UK_Photex },