Height and gradient from shading

Berthold K. P. Horn. Height and gradient from shading. International Journal of Computer Vision, 5(1):37-75, 1990. [doi]

@article{Horn90a,
  title = {Height and gradient from shading},
  author = {Berthold K. P. Horn},
  year = {1990},
  doi = {10.1007/BF00056771},
  url = {http://dx.doi.org/10.1007/BF00056771},
  researchr = {https://researchr.org/publication/Horn90a},
  cites = {0},
  citedby = {0},
  journal = {International Journal of Computer Vision},
  volume = {5},
  number = {1},
  pages = {37-75},
}