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Surface Approximation 1243
Renderer, Displaced Surface:
Method=Spatial and Curvature Edge=10.0
Distance=10.0 Angle=4.0 Merge=(Unavai lable)
Advanced Parameters > Minimum=0,
Maximum=3
Keyboard shortcut: ALT+2
High—Selects a high-quality surface
approximation.Thesearethedefaultvalues:
View ports, Base Surface:
Method=Sp atial and Curvature Edge=5.0
Distance=15.0 Ang le=10.0 Merge=0.0 Advanced
Parameters > Minimum=0, Maximum=3
Renderer, Base Surface:
Method=Sp atial and Curvature Edge=5.0
Distance=5.0 Angle=3.0 Merge=0.0 1 Advanced
Parameters > Minimum=0, Maximum=4
Renderer, Displaced Surface:
Method=Sp atial and Curvature Edge=5.0
Distance=5.0 Angle=2.0 Merge=(Unavai lable)
Advanced Parameters > Minimum=0,
Maximum=4
Keyboard shortcut: ALT+3
Note: The keyboard shortcuts for surface
approximation presets don’t require that the
K eyboard Shortcut Override Toggle be on. You
can change the surface approximation of NURBS
objects by selecting them in a viewport, and then
using ALT+1, ALT+2,orALT+3.Thisworksfor
sub-objectsaswell,butthesurfacesub-object’s
Lock to Top Level toggle must be turned off.
Tessellation Method group
The controls in this group affect the display of the
NURBS surface in viewports if you have chosen
Viewports above, or by the renderer if you have
chosen Renderer above. You can choose between
five algorithms. Each approximates NURBS
surfaces by tessellating them in a different way.
Generally spe aking, if the preset values you have
chosen give good results, you don’t need to adjust
thecontrolsonthisrollout. Adjustthemifyou
encounte r problems with the preset alternative.
Tips
• Viewpor t Tessellation: The tessellation method
creates the m esh. If you modify the NURBS
object with
Mesh S elect (page 1–710) ,choose
the method that gives the result you need. If
you use modifiers heavily, Spatial or Parametric
might be b etter than Curvature, because of
their regular tessellation. Curvature-dependent
tessellation can cause problems with some
modifiers.
• Renderer Tessellation: Spatial and Curvature
usually obtains the most accu rate rendering.
Curvaturecanbethemoreefficientchoice
when you render an imated surfaces.
Lock t o Top Lev el —(for sub-object surfaces only)
When on, the surface sub-object uses the same
surface approximation settings as the top-level
NURBS model, and other controls on this rollout
are disabled. When turned off, you can set t he
sub-object approximation to differ from the
top-level model. Default=on.
Regular—Generatesafixedtessellationacrossthe
surface based on U Steps by V Steps. Increasing
these parameters increases accuracy at a cost of
speed, and vice versa, but in general this can be the
quickest and least accurate way to approximate a
NURBS surface. Very low values for U and V Steps
using the Regular metho d usually doesn’t provide
good results. Model complexity increases slowly
as U and V Steps values increase.