- D. Hougen and N. Ahuja, Integration of Stereo and Shape from Shading using Color, Proc. Second International Conf. on Automation, Robotics and Computer Vision, Vol 1, Singapore, September 15-18 1992, pp. CV-6.6.1 – CV-6.6.5.
- D. Hougen and N. Ahuja, Estimation of the Light Source Distribution and its Use in Shape Recovery from Stereo and Shading, 4th Int. Conf. on Computer Vision, Berlin, Germany, May 11-14, 1993, 148-155.
- Darrell R. Hougen and N. Ahuja, Adaptive Polynomial Modelling of the Reflectance Map for Shape Estimation from Stereo and Shading, Proceedings IEEE Conference on Computer Vision and Pattern Recognition (CVPR), Seattle, WA, June 1994, 991-994.
- D. Hougen and N. Ahuja, Shape from Appearance: A Statistical Approach to Surface Shape Estimation, Proceedings European Conference on Computer Vision, Cambridge, England, April 1996, 421-429.
- M. Singh and N. Ahuja, Estimating Light Sources, Indian Conference on Computer Vision, Graphics and Image Processing, New Delhi, India, December 1998, 76-81.