Bibliography

@Article{Masuda/Numao:1997,
  author=       { Masuda, Hiroshi and Masyuki Numao },
  year=         { 1997 },
  keywords=     { ORTHOGRAPHIC PROJECTION SOLID MODEL NON-MANIFOLD ATMS },
  institution=  { Tokyo Research Laboratory },
  title=        { A Cell-Based Approach for Generating Solid Objects from
                  Orthographic Projections },
  journal=      { Computer-Aided Design },
  volume=       { 29 },
  number=       { 3 },
  pages=        { 177-187 },
  annote=       {

This paper describes a method for converting orthographic projections into solid models using Non-Manifold Topology and ATMS ( Assumption - based Truth Maintenace System ). The paper also discusses methods to find errors ( missing or extra lines ) in the given projections. The main innovation is the use of an intermediate stage - Cellular Model, between the wireframe model and the final solid model. The wireframe is broken down into 'n' primary solids (Cells), which facilitates the final selection of the correct solid as there only 2^n possible combinations. The selection of the cells is based on solution of constraints between the cells and the projections.

NOTE - The algo doesn't consider the information whether a particular line is a hidden line or a firm line. All hidden lines are therefore to be input in a manner equivalent to that for firm lines.

LIMITATIONS - Projections consist of straight lines, circles or ellipses and solid models consist of planes, cylinders, cones, tori and spheres ( the directions of the cylinders, cones and tori are constrained to be parallel to any of the primary axes).

                                                  
                                                  - Mohan Kishore, and
                                                    Amit Nagpal 8/97 }, }