Manifold-based multiple-viewpoint CAD: a case study of mountain guide-map generation

There are kinds of picture that are drawn with multiple viewpoints. Mountain guide maps, cubism pictures and medical-diagnosis drawings are examples of such pictures. So far, however, they have been drawn intuitively by hand. Implementing a CAD system for such pictures requires clear modelling of their drawing processes. As a case study, the paper presents mountain guide-map modelling using manifolds, and the implementation of multiple-viewpoint CAD based on the model. A local land surface is designed using critical points such as peaks, pits and passes. The local surfaces are then pasted together to form the manifold representing the whole surface. Surface shapes in the overlapping areas are blended using a partition of unity. Projecting a land surface as seen from multiple viewpoints is conducted interactively using the CAD system. Then, the mountain guide map is generated automatically.