Observational Models of Graphite Pencil Materials
Author(s): Mario Costa Sousa, John W. Buchanan.
Article: Computer Graphics Forum, Vol. 19, No. 1, pp. 27--49, March,
2000.
[BibTeX] 
Abstract:
This paper presents models for graphite pencil, drawing paper, blenders, and kneaded eraser that produce realistic looking pencil marks, textures, and tones. Our models are based on an observation of how lead pencils interact with drawing paper, and on the absorptive and dispersive properties of blenders and erasers interacting with lead material deposited over drawing paper. The models consider parameters such as the particle composition of the lead, the texture of the paper, the position and shape of the pencil materials, and the pressure applied to them. We demonstrate the capabilities of our approach with a variety of images
and compare them to digitized pencil drawings. We also present image-based rendering results implementing traditional graphite pencil tone rendering methods.