Hi guys!
I´ll be releasing a new version of the dual quaternion plugin after
xmas holidays. Scaling (and some other small improvements) will be
added to this new release. Not sure if I will have time to include
speed optimizations...
I agree with all of you. Dual quaternion is a new tool that is based
on a very specific mathematical solution. It helps with some of the
problems, but is not a perfect solution, and of course, these rigger´s
magic tricks will not be replaced :-)
Cheers
Fernando
On 12/18/07, Philipp Oeser <philipp.oeser(at)liga01.de> wrote:
> Totally agreed...
>
> I was just spreading the word for the rigger here (who up until now is quite
> happy with what he sees...)
> (still: what he noticed was this strange behaviour on scaling which doesnt
> seem to occur in the other implementations...)
>
>
> Bradley Gabe schrieb:
> Dual Quaternion skinning offers a different mathematical approach to solving
> for deformation, but it alone by no means is *the* solution. It's the
> proverbial procrustean bed, some things improve but at the expense of
> others. While volume is better maintained at joint centers and candy-wrapper
> twists go away, the resulting deforms still don't look natural, and in some
> cases look worse than what you get with the traditional envelope algorithm.
>
> The main issue for us as riggers has always been trying to figure out clever
> ways to isolate our rotational axes per joint in order to distribute
> different types of deforms per joint motion. Example, an elbow rig. Assuming
> a standard XSI IK chain, we bend the elbow by rotating the second arm bone
> in the z axis, and twist the forearm by rotating it in the x axis. The elbow
> bend is best if the effect is localized close to the joint center. The
> forearm twist, we would rather distribute down the length of the forearm
> towards the wrist. A dual quaternion solution doesn't isolate those two
> deforms, we will still have to do that via rigging. And while the dual
> quaternion solution will keep our forearms from losing volume as they twist,
> it's going to be debatable as to whether they look better on the elbow bend.
>
> Here's where the future actually looks bright for those of us without
> cMuscles built into our software. The more ideal solution for the
> deformation problem does not lie in an all or nothing algorithm, and
> possibly not in someone else's pre-canned muscle system. I suspect, the more
> ideal solution will be found in a conditional deformation system. One where
> we get to choose from many different types of deforms and have them
> activate, blend, and normalize based on a set of kinematic rules... When the
> forearm rotates in the z-axis, apply an 80-20 blend of dual quaternion to
> traditional envelope. When the elbow rotates in the z-axis, apply a 20-80
> blend, along with a localized push operation... Basically, we're taking all
> the jiggering away from the externals of rigging and moving them to the
> internals of the deformation system where they can be out of the way of the
> animators, and nicely multi-threaded. :-)
>
>
> On Dec 18, 2007 9:24 AM, Philipp Oeser <philipp.oeser(at)liga01.de> wrote:
> Hi,
> it really is an improvement over the "regular" envelope, thanx
> again...slowdown can be noticable but what the heck...
> One thing though:
> Scaling seems to be quite different than the "regular"envelope. Ladislav
> Kavan talks about solving this limitation in his realtime approach by
> having extra vertexshader instructions.
> Is there something like this in the current implementation?
>
> In any case: thanx!
> Philipp
>
>
>
>
> Fernando Navarro schrieb:
>
> > Hi all:
> > I have released a new envelope operator that implements dual
> > quaternion interpolation. It has been designed to replace the existing
> > envelope operator using the same inputs (deformers, weights, ...). It
> > can be used with NURBS surfaces and curves, polygonal surfaces and
> > lattices.
> > As part of the package I have written a brief explanation that will
> > help you understand the differences between the traditional and this
> > method.
> >
> > You can download it at
> http://www.highend3d.com/f/4977.html
> >
> > It's a working release but can be improved. If you have and
> > suggestion or find a bug, just drop me a line...
> >
> > Hope you enjoy it!
> > Fernando
> > ---
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> >
> >
>
>
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LIGA_01 COMPUTERFILM GmbH
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MUNICH
Landwehrstrasse
> 60-62
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fon: +49 - (0)89 - 51 555 8-88
fax: +49 - (0)89
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