Generating Topological Information from a "Bucket of Facets"

The STL de facto data exchange standard for Solid Freeform Fabrication represents CAD models as a collection of unordered triangular planar facets. No topological connectivity information is provided; hence the term “bucket of facets.” Such topological information can, however, be quite useful for performing model validity checking and speeding subsequent processing operations such as model slicing. This paper discusses model topology and how to derive it given a collection of unordered triangular facets which represent a valid model.