ABSTRACT
The Wire Frame algorithm described in the previous chapter was based on the concepts of algebraic topology and rigorous definitions of the geometric entities
We now extend the Wire Frame algorithm to polyhedral objects described by a set of two dimensional projections such as might be seen on an engineering drawing. The projection process may introduce another level of ambiguity into reconstruction problems and increases the possibility of there being many objects with the same set of projections. The Projections algorithm presented here can work with very little information, for example, only two projections, and find all possible objects matching the data. However, it is seen that the number of solutions may be very large and that it may be reasonable to provide more information in the form of three or more projections, by labeling corresponding features in divers views, and by providing depth information. The Projections algorithm is able to make use of this extra information and can also accept other forms of advice, such as whether given points are inside material.
