Thank you very much, Thomas,
that's what I needed to understand.
ThomasL wrote:One can hope that it is possible to do most of the deformation with bones alone. E.g., the pose above could be improved with a deltoid bone stretching to the upper arm. In T-pose this leads to problems when the arm bends down, but if the arm is already down in rest pose a deltoid should work better.
I think considerations like these are in the vicinity of the
scalar rigging¹ issue I mentioned, and afai see any solution meant to maintain interoperability with industry standard animation systems has to deal with that; and of course esp those with the stricter constraint of COLLADA / X3D (hanim) "encodability".
The two usual ways to deal with that
- "synthetic" bones, like the "deltoid bone" you propose
- and "event" based morph correction, like e.g. made available by (esp. bone-)driving blender's shape-keys,
none of them being overly attractive.
The other way is what animorph did - using a proprietary pose system at the price of giving up interoperability; esp with IK-solutions.
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Summing up - there is an issue.
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But this
ThomasL wrote:This will affect all rigs to some extent, due to the need for non-trivial roll angles.
(
emphasis mine)
to me appears a sort of
brute force refactoring - I don't need a crystal ball to predict that this will trigger changes to the mesh itself, which may have side-effects which may trigger further changes and... - you get the idea.
I've followed the makehuman development sporadically for quite some time now and I sometimes had had some doubts if the project would get to a point which justifies reconsidering vertical ranges of production for professional usage.
That point imo appears now in reach - excellent job by you and your team, btw!
Thus I'd like to reiterate my idea about a sort-of "dual" solution - only minor fixes within current conceptual bandwidth not risking made milestones and conceptual innovations only by means of the "extra" paradigm I tried to sketch in the aforementioned thread.
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The other thing I'd like to suggest is a sort of adaption of the concept of "effective theories" in science:
Regardless of how a certain final pose state will be achieved - there is e.g. sth like a (however weighted, however posed) lower leg, and that certain leg has a (however parttitioned) surface and a certain volume.
viewtopic.php?p=19599#p19599Solkar wrote:I'm wondering if, because of the very simple form of the backside of the human leg from just underneath buttock to just above ankles, one could try surface fitting that with a low-order polynomial and work with a bit of diff'geo and measure to get a correct volume-preserving morph.
Those real constraints given, one can try and deduce whatever model-specific realization of those constraints.
That way one could get a collection of model-independent assets which would survive even the most crude refactoring needs, or am I mistaken?
Best regards, S.
¹I'n not "married" to that phrase, but I wanted to coin one.