9

1086 Chapter 9: Surface Modeling
Moving and rotating CVs to change a surface (selected CVs are
displayed in red)
Each CV also has a weight, which you can use
toadjusttheCV’seffectonthecurveorsurface.
Increasing the weight pulls the sur face toward the
CV. Decreasing the weight relaxes the surface away
from the CV.
Above: Weights=0.0
Below: Weights=40.0
Changing a spherical surface by decreasing or increasing the
weight of four CVs (selected CVs are at the left, in red)
Weight s c a n b e a u seful way to " tune" t h e
appearance of a NURBS curve or sur face.
The weight value of a CV is rational (as in a
"rational number"). That is, it is relative to other
CVs in the c u rve or surface. Chang ing the weight
of all CVs at once has no effect, because it doesn’t
change the ratio between weights.
Points,PointCurves,andPointSurfaces
PointcurvesandpointsurfacesaresimilartoCV
curves and sur faces, but the points that control