9.5.2

408 • CHAPTER 7
OBJECTS MENU • DEFORMERS • 409
Restricting bones using polygon selections or vertex maps
In the previous section we used the Limit Range option to restrict the inuence of bones. Bones can
also be restricted using polygon selections or vertex maps (or Claude Bonnet maps if you are using
the MOCCA module); in fact you can use polygon selections and vertex maps to restrict the effect of
any type of deformation object.
In the previous section we were able to restrict the bones in a leg quite effectively using radii. However,
most conventional life-forms have at least two legs — as you can see in the picture below, the radii on
the left leg spill over onto the right leg, causing problems when the legs are animated.
You can solve this problem by dening either a polygon selection or a vertex map for each leg. There is
no need to dene a restriction for each part of the leg — it is sufcient to restrict each leg as a whole.
For our example, a polygon selection per leg is adequate, since the points in the HyperNURBS cage
are spread out. If, on the other hand, you are using an object with a high point density, vertex maps
are the better option in order to obtain a smooth transition at the edges of bones. In any case, the
procedure for both methods is identical, i.e. the following applies to vertex maps as well as polygon
selections.
The polygon selection will restrict each leg as a whole. This means that we still need to use limited radii
(see above) to further restrict each bone, e.g. so that the foot bone of the left leg will only inuence
the foot region of the left leg.
We can use our HyperNURBS leg from the previous section. The bones already use the limited radii
that we require. Use the Mirror command (Structure > Mirror) to mirror the leg to create a second leg.
Now, select all the polygons of the leg which contains the bones and choose Selection > Set Selection
from the main menu. Name the selection ‘left leg’.