9.5.2

428 • CHAPTER 7
OBJECTS MENU • DEFORMERS • 429
Hints and tips
Quality rst
Using Boundary Curve Preservation always gives good results if you want to preserve the original mesh
boundaries of non-manifold objects i.e. objects that are not entirely closed. For a manifold object
(sphere, capsule, cube etc.) it makes no difference if this check is on or off since the algorithm detects
manifold objects automatically and deactivates boundary checks if they are on.
Using the Polygon Quality Preservation check is very helpful with objects that have co-planar faces
(faces with polygons in the same plane), such as cubes or planes. The result of using this option is that
the generated mesh is very well distributed and this leads to a substantially faster reduction process,
as long as no clustering-points (points that have a large number of neighboring edges) appear in the
reduction process.
Tests show that using sliver checks (Polygon Quality Preservation) gives a better mesh when applied
to objects with no co-planar faces and a major improvement in the mesh when working with co-
planar faces.
With some objects like a cone, a sphere, a circle etc., which have one or more
central points in the mesh, around which there are many edges, it is normal for
the algorithm to keep the clustering as high as possible at this point, because
the point is not generated during the process of reduction, but exists in the
base mesh.
Here is an example of sliver triangles generated as a result of the reduction (if the Polygon Quality
Preservation option is not used):
... and sliver triangles preserved when this option is on, due to their existence in the original object
mesh:
Such preservation results from the fact that the algorithm detects that collapses in the area of the
slivers will lead to other slivers and therefore postpones the reduction. As you can see, adjusting these
quality factors can inuence very strongly the way in which the reduction process proceeds.