.
Flattening 3D objects using silhouettes
Domingo Martín, Jean-Daniel Fekete, J. C. Torres.
Computer Graphics Forum (EG'02), Vol. 21, No. 3,
2002. [BibTeX]
Observer Dependent Deformations In Illustration
Domingo Martín, S. García, J. C. Torres.
1st International Symposium on Non-Photorealistic Animation and Rendering (NPAR'00), pp. 75--82, Annecy, France, June 5-7,
2000. [BibTeX]
Pen and Ink Pictures from Gray-Scale Photographs
Author(s): Germán Arroyo, Domingo Martín.
Proceedings: EUROGRAPHICS 2003, Interactive Demos & Posters,
2003.
[BibTeX] 
Abstract:
A new method for producing pen and ink pictures from gray-scale photographs is introduced in this article. It is based on path-finding and reconstruction of strokes. First we apply filters to extract contours from photographs which are converted to strokes, then we show how to modify these strokes in the same way an artist could do it. The strokes are not pixel-based but bspline curves, which are rendered simuling different kinds of brushes and papers.
Silhouette detection in volumetric models based on a non-photorealistic illumination system
Germán Arroyo, Francisco Velasco, Domingo Martín.
Computers & Graphics, Vol. 29, No. 2, pp. 209--216, April,
2005. [BibTeX]