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Dual Quaternion Skinning

Quasar
polycounter lvl 19
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Quasar polycounter lvl 19
Hey guys

I'm curious about whether any of you have any experience using dual quaternion skinning and what you think of the system. I haven't seen it in any games yet but there are many papers written on the subject and it looks like it puts our good old linear blend skinning to shame since it doesn't allow geometry collapsing. It's been around for some time now, and with its advantages, I'm wondering why it hasn't been implemented into games yet. As far as I know, it hasn't even been implemented into Maya or MAX by the developers, which I find odd considering Blender supports it. Here's a link with some info about this system for those unfamiliar.

Cheers!
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  • James Edwards
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    James Edwards polycounter lvl 18
    There's a plugin for XSI 6 that enables it. I think there's one out there for maya too, though i haven't tried it. XSI 7 will support it natively. Once the major 3d apps all support it I'm sure you'll see more games supporting it.

    Just noticed your link was the one with the maya plugin link =]
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  • MoP
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    MoP polycounter lvl 18
    We have it built into ETQW. Works fairly well especially around wrists and shoulders. Noticeably better volume is kept.

    And if I remember right, I think someone said there was a script or tweak you could do in Maya to use that. I might be mistaken though.
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  • Rick Stirling
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    Rick Stirling polycounter lvl 18
    Doesn't Crysis use a non-lienar method? Was it spherical?
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  • MoP
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    MoP polycounter lvl 18
    Crysis uses the same thing, yeah, it's just a different name for the same thing if I remember right.
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  • Joao Sapiro
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    Joao Sapiro sublime tool
    yeah this is something i was wondering how to do , my rigging is only limited to biped on max unfortunately, but would be awesome to know how to implement this, since colapsing areas are a problem when posing ( looks good in a angle, in the other weird )
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  • Rick Stirling
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    Rick Stirling polycounter lvl 18
    Last time I looked there was no available max plugin to approximate non-linear skinning in the viewport.

    Biped on it's own won't be enough to give you a non-collapsing sweetie-wrapper effect, but you can avoid that by adding more bones in series in the limbs.

    Non-linear skinning is more expensive at runtime, however you can get away with using less bones, so there is good chance that the two things cancel each other out.

    I HAVE NO EVIDENCE OF THAT, it's just my line of reasoning.
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  • CrazyButcher
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    CrazyButcher polycounter lvl 18
    rick I doubt your speculation there would work, because less bones = less matrix updates, which is "per object", while dual quaternion and so on are more costly per vertex. which you have more of.

    neither do I have tested this, but I think the reasoning works.

    the new graphics cards have more arithmetic power so that these techniques will become more and more popular with time I guess.
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  • Rick Stirling
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    Rick Stirling polycounter lvl 18
    Curses!

    So, is there any hard data out there? (I know, 'it depends')
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  • Quasar
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    Quasar polycounter lvl 19
    Thanks for the info, I didn't know there are engines using it already!

    Gwot - Yeah, I know there are plugins, what I meant was that I find it odd how it's not supported natively. Just seems like a feature you'd expect in high end programs nowadays.

    Mop - What kind of pipeline did you guys develop for using it? Did Splash Damage write plugins for max/maya to preview, or did you guys just weight the models and hoped it looked good in game?
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  • MoP
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    MoP polycounter lvl 18
    Quasar: It was added as a rendering option long after the character models were skinned and rigged. Since they were rigged with standard linear blending in mind, there's not a huge amount of noticeable improvement from using the dual quaternion set, since the meshes were designed not to collapse when deforming anyway. The most noticeable places that it helps are around the wrists when holding weapons a certain way, and a bit more volume around the shoulders.
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  • Quasar
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    Quasar polycounter lvl 19
    Ah, ok. Thanks
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  • websta
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    websta
    Extension 2 for 3ds max now has dual quaternion tool within the skin madifier.
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  • marks
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    marks greentooth
    Just the thought of quaternions ... *shudders*
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  • websta
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    websta
    Let alone dual ones....
    A hard modeler mainly, but when I have modeled a character I have always found Max skin a little clunky and sometimes a bit of a fiddle to get thing looking just right.
    Now with dual quaternion it seems I have another layer of control that so far I have had no luck with.
    Those corporate 'shoow off vids' are kindof exasporating when they show it all working fine withought a clear instruction on how.
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