This workflow guides you on how to refine and enhance your render skin after running muscle and tissue simulations. There is no single way to deform your render skin with the simulated tissue. Some useful suggestions and nodes to consider:

1. Use a File Cache SOP to cache your simulation to disk. To reduce disk space usage, you can optionally do some or all of the following before caching:

   • Use a Convert Tets SOP to delete any tetrahedra and only keep the surface polygons of the muscle and tissue.

     • OR Blast everything except the tissue_outer_surface primitive group if you only want to deform the final skin with the tissue.

   • Use a Group Delete SOP to delete any unneccessary groups.

   • Use an Attribute Delete SOP to delete any attributes not needed downstream. Note that the Otis Muscle and Tissue Configure SOP already deletes a number of attributes, so if there are specific attributes you'd like to keep, you might have to specify them on that node first.

2. Create a mask attribute on your render mesh to control which areas get deformed by the simulation. One of the many ways to do this is demonstrated in the Test Geometry: Otto Muscle and Tissue Simulation or the Otis Muscle and Tissue Simulation deform_skin subnet.

3. Use a Skin Deform SOP with the render skin animation as the first input, and the simmed tissue outer surface as the second input, to deform the former with the latter.

   • Regions that aren’t affected by the sim, such as the head, hands, and feet, can be excluded from the deformation with an attribute, as suggested in the previous step. The regions outside that mask attribute will maintain their incoming animation.

   • Ensure both inputs have a tpose attribute. Note that if the tpose attribute was deleted before simulation/caching, it will have to be copied over or recreated.

   • Set the Reference Frame to your start frame.

   • Turn on Skin Sliding to allow quasistatic skin sliding which gives simulation-like results.

4. If you want to procedurally add wrinkles to the deforming skin, use a Wrinkle Deformer SOP.

   • Use attributes to control the wrinkling behaviour in different regions.

   • Note that the size of the wrinkles is limited by the resolution of the render skin.

   • See Wrinkle deformer –> How to for tips on how to control the look of your wrinkles.

5. The Delta Mush SOP is useful for fixing distortions in the skin mesh.

6. The new Shot Sculpt SOP is an easy way to manually sculpt fixes over specific frames.

   • You can use a Delta Mush SOP or Wrinkle Deformer SOP as a Blendshape Target to paint regions which blendshape to those targets and control which frames the blendshapes are applied to.

   • If there are regions of your skin that have exploded points, such as limbs interpenetrating, you can use a Delta Mush SOP or Smooth SOP as a Blendshape Target rather than the Smooth brush in the Shot Sculpt SOP. This can be more stable over multiple frames where the points are changing their relative positions alot from frame to frame.

   • The Shot Sculpt Pane should be used in conjunction with the Shot Sculpt SOP.