Parallel Algorithms for the Interpretation of Line Drawings

This paper describes the design and the analysis of parallel algorithms for the interpretation of planar or perspective projections of scenes constructed by some generating grammar (trihedral scenes, Manhattan world, Origami scenes, Pottery world). The motivation is that parallel techniques are more and more studied in Arti cial Intelligence and Computer Vision as parallel machines improve their performances and parallel models have been successfully proposed for biological systems, so that it is possible to attempt a methodological identi cation between algorithms which are easily parallelizable and biologically plausible algorithms. It is found that the labeling problem (Hu man, 1970; Clowes, 1970) is e ciently solvable in parallel when it is polynomially tractable. The realizability problem, which is usually solved by linear programming methods, is hard to parallelize in the general case, while it is parallelizable when the vanishing points are known. All the results point to the importance of heavily exploiting geometrical regularities to devise biologically plausible visual algorithms.