Overview of 3D Object Representation

3D Object Representation: Surfaces vs. Solids

Surfaces – Mesh

• Group of connected polygons (usually triangles)– May not be closed

Surfaces – Subdivision Surface

• Coarse mesh & subdivision rule– Define smooth surface as limit of sequence of

refinements

Zorin & SchroederSIGGRAPH99 course notes

Surfaces – Parametric Surface

• Tensor product spline patches– Careful constraints to maintain continuity

FvDFH Figure 11.44

Surfaces – Implicit Surface

• Points satisfying F(x,y,z) = 0

Bill Lorensen SIGGRAPH 99 Course #4 Notes

Solids – Voxels

• Uniform grid of volumetric samples– Acquired from CAT, MRI etc.

Solids – BSP Tree

• Binary space partition with solid cells labelled– Constructed from polygonal representations

Solids – CSG

• Hierarchy of boolean set operations (union, difference, intersect) applied to simple shapes