Modelling for Animation |
| In addition to making sure that the face has the correct flow of edges to allow for realistic animation, there are other areas where animation needs to be considered during the modelling process.
By taking into account how the model will deform, it is possible to adjust the placement of vertices and hence edges to allow for a more believable shape as the character is animated.
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Step 1 |
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Here is a simple example of how the position of the edge loops can affect the
deformation of a mesh. Each cylinder is the same, using a couple of bones and a skin
modifier, however one of the cylinders has been adjusted, as you can see in the viewport
images. The edges have been moved in the direction of the deformation. So in this case, the
top of the cylinder has had the edges moved apart in the area that would bend together
while the bottom edges of the cylinder are moved together as they will stretch apart when
the mesh bends. |
Step 2 |
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With the cylinders bent, you can see how adjusting the vertices affects the
deformation. The one that was left as straight cross-sections, now tends to bend and cut
into itself, while the other cylinder which was modelled with the bending action in mind
has not yet started to fold in on itself. Of course the most likely area on a human
character were something exactly like this would be used is on the elbows and knees. |
Step 3 |
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With a meshsmooth applied you can more clearly see what difference adjusting the
cross-sections can have when the mesh is deformed. While this technique is unlikely to do
away with the need to still re-shape the deforming mesh (i.e. using a morph deformer based on
bone rotation), it does provide a better starting point. |
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| Nothing is perfect and this technique is no exception. Were problems can arise is when
there is a conflict between modelling for animation and modelling for overall shape and
form. At times, in order to get the model looking right, vertices and edges many need to be
moved closer together. However this area may also be a spot that will bend in, hence
needing the vertices and edges to be moved further apart. When this happens the best that
one can do is make a compromise, which generally leans more towards a correct shape as there
are other techniques that can be used to "fix" deformation problems. |
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