@article{kay-cae-95-parst,
  author = {G. Kay and T. Caelli},
  title = {Estimating the Parameters of an Illumination Model using Photometric Stereo},
  journal = {Graphical Models and Image Processing},
  volume = {56},
  number = {5},
  pages = {365--388},
  month = sep,
  year = 1995,
  comment = { Determines normals and albedos. Assumes a linear combination of Lambertian and specular (including glossy) components.  Uses nonlinear regression. For real objects succeeds only in {30\%} of the pixels.}
}