maya建模的問題~

[cityheart1980]

NURBS與POLYGONS差別在那??

[Itoshin]

單就視覺上來看.....NURBS是曲面構成，Polygon是多邊形構成....

[johngalliano]

NURBS(Non-uniform rational B-spline)
-a parametric (has uv) four-corner patch (quadrilateral),
-u tangent and v tangent are well defined,
-uv parametization can be uniform or non-uniform(refer to the doc),
-can be rational or non-rational (non-rational surface has its CVs weights all equal),
-can be of different degree or order (e.g cubic(degree 3, order 4), linear(degree1, order 2))
-has knot values, for reparametization, mimic spline of other basis (e.g bezier), multiplicity. (Refer to Renderman Companion pg 104-105, and Advanced Renderman pg 105-106 for details)
-can trim a nurbs surface (but better not to do it)
-need tesselation b4 rendering in maya.

Polygon
-no clear parametization
-uv (so called in maya) has to be projected onto the polygons
-can have as many sides as u want (but 4-side is usually good)
-can safely make holes on a polygon model
-need to be subdivided or smoothed b4 rendering