1/28/2004   slide 13
Rule 3: Collinear Lines
Stay Collinear
•“Always interpret lines collinear in an image as collinear in 3D.” [Hoffman 1998 p31.]
Works by Shigeo Fukuda
Collinear lines in projection (or scene from one point of view) usually indicate collinear lines in real 3D form—and these stay collinear independent of view.

Presentation on perceptual grouping of line segments
http://astro.temple.edu/~sandeep/Pptseg.ppt#1