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Deformation Weighting Layers
Each GeoH object has a vertex map that says which portions of the mesh should be deformed with it, ie carried along with the GeoH object. Weighting can be used to set up transition regions, where a vertex may be affected only 60% by the one object and 40% by another (typically parent or child), for example.
For example, in a hierarchy that deforms a 3D mesh of a person, the left upper arm object affects the upper arm; the left forearm bone affects the forearm vertices, and the elbow region is affected by both. Weights are typically massaged carefully to produce sensible deformations over the range of motion.
Warning : SynthEyes versions prior to 2019 defined weight maps a bit differently.
Note : Weight maps are managed such that the weights on each vertex total to 100% (1.0). The GeoH Check Weights script can check and correct them.
The vertex maps can be set up using the following methods from the GeoH toolbar or panel (you can consult their tooltips for additional information or for reference):
the GeoH Auto-Generate Weights script,
the GeoH Surface Lasso tool,
the GeoH Thru Lasso tool,
the GeoH Paint tool,
the GeoH Airbrush tool,
the GeoH Blur Weights tool,
the GeoH Soften Now button, or
the Vtx Maps button for externally-painted image maps.
The Auto-Generate Weights script is designed to give you a quick initial set of weights for typical rigs such as people and quadrapeds. It's probably not going to be as helpful setting up maps for facial deformations and other close fine-detail work. In any
case, once you've run it, you will need to improve it, using the same following tools that you need to use whether you use auto-generation first or not.
With the two lasso tools, lassoing vertices adds them to the map for the currently- selected GeoH object; control-lassoing removes them from the map. (Note that shift- lassoing lassos them into a new GeoH object, as described previously.)
Warning: Vertex maps are necessarily forgotten if the mesh is carelessly reloaded, replaced, or edited (ie the number of vertices changes). See Replacing the Mesh and the GeoH Mesh Replace Script.
The Surface lasso takes only the vertices visible on top, whereas the Thru lasso takes vertices all the way through the mesh. Use Surface to work on a face, for example, and Thru to easily set up maps for an entire arm where both front and back side should be added in one step.
Tip: you can use "blocking planes" in the middle of a mesh to control which vertices are painted or airbrushed. For example, you could use Thru mode with a blocking plane, between an arm and the torso, to work on just the arm, not the torso.
If you've lassoed some vertices, you can generate a smooth blend region outside of them using the GeoH Soften Now button, which uses the Range control to determine the world-coordinates size of the blend region.
Tip : Soften Now is good for setting up big hierarchies. Start at the root, setting up weights for the upper arm, say, which include the lower arm and hand etc, using a big lasso. Then you can use Soften Now to soften back upwards as needed. Then carve out the weights for the child bones.
The paint tool is similar to the surface tool, except that it operates only on vertices within the radius of the brush. The radius can be controlled, as can the weight of the brush, which can be used to set up partially weighted vertices.
The airbrush tool is liking painting, but the weight accumulates steadily as you continue to airbrush a particular set of vertices. You can change the rate at which that happens using the Flow parameter.
Especially with airbrushing, you can adjust the weights by manually changing the locked joint values of the object hierarchy to move an object to a fairly extreme position. Then you can airbrush (adding and subtracting) to achieve the desired deformed shape at the extreme position. You can test it through its range of motion, adjusting as needed, before putting it back to its nominal position.
Tip: While painting or airbrushing (or smudging), you can use Hide bones and Hide handles buttons to hide the respective elements, simplifying the view and making it impossible to accidentally click those items.
You can blur the weights to smooth out transitions and eliminate small holes or peaks in the weight maps. The Blur Weights tool operates on all weight maps for the mesh, not just the map for the currently-selected object.
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