8 Skinning

8.5 Resolution and Limitations

Skinning techniques do have limitations, which are common to all methodologies.

Figure 8.5: A skin mesh enveloping a single FEM body whose element resolution is lower than that of the mesh (left). When the FEM undergoes a large deformation, this disparity in resolution can cause artifacts such as crimping, as seen on the underside of the mesh in the middle image. Using an FEM model with a higher resolution can mitigate this (right).
  • The passive nature of the connection between skinned vertices and the master bodies means that it can be easy for the skin mesh to self intersect and/or fold and crease in ways that are not physically realistic. These effects are often more pronounced when mesh vertices are relatively far away from the master bodies, or in places where the mesh undergoes a concave deformation. When the master bodies include frames, these effects can sometimes be reduced by setting the frameBlending property to DUAL_QUATERNION_LINEAR instead of the default LINEAR.

  • When the master bodies include FEM models which undergo large deformations, crimping artifacts may arise if the skin mesh has a higher resolution that the FEM model (Figure 8.5). This is because each mesh vertex is connected to the coordinate frame of a single FEM element, and for reasons of computational efficiency the influence of these coordinate frames is not blended as it is for frame-based master bodies. If crimping artifacts occur, one solution may be to adjust the mesh and/or the FEM model so that their resolutions are more compatible (Figure 8.5, right).