Digital representation schemes for 3d curves

Digital representation of three dimensional curves is considered. Two dimensional representation schemes are rst reviewed, then methods applicable to curves in three and higher dimensional spaces are described. Desirable properties of curve representation schemes are identiied 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 identiied requirements and should be preferred.