Digital representation schemes for 3D curves

Digital representation of three-dimensional (3-D) curves is considered. Two-dimensional representation schemes are first reviewed, then methods applicable to curves in three and higher dimensional spaces are described. Desirable properties of curve representation schemes are identified and used as a basis for qualitative and quantitative comparison of the various methods that have been suggested. Conclusions concerning the selection of a digital 3-D curve representation scheme for shape analysis and coding are drawn. It is shown that grid intersect quantization is a poor choice for curve representation in 3-D space and that cube quantization, that leads to 6-connected chain codes, meets all the identified requirements and should be preferred.