ICE Delta Mush

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Delta Mush ICEAuthor: Miquel Campos
updated with a compiled version by Guillaume Baratte. »Delta Mush« is a mesh deformer that fixes/softens the effect of other deformers without affecting high-res details of the mesh. It's been developed in 1997 but was made public only recently in demo videos of former Rhythm & Hues in-house software »Voodoo« where it was exclusively used. The idea behind Delta Mush is simple but clever: Local mesh detail (=per point offsets from a smoothed to the original undeformed mesh) is precomputed and stored. Then the 'to-be-fixed-deformer' is applied, directly after which the mesh is smoothed again with the same smoothing algorithm. This removes newly introduced detail which could potentially include unwanted artefacts from the deformer. Finally, the stored offsets are applied, restoring the original detail.

This works not only for envelopes, but for all kinds of deformers like cloth sims. On envelopes, it is similar to what weight smoothing does, but (at least in theory) should be able to enhance the envelope effect by adding some sliding movement along the surface of the smoothed mesh. This can't be achieved using enveloping which only does rotations around the joints.

There are two implementations for Softimage. The first one is Miquel's original ICE compounds. The precomputation is done using the »Delta_Mush_dataSet« compound in the modeling stack, with the post effect applied in the animation stack after the envelope using the »Delta_Mush« compound.

local backup: Delta_Mush_dataSet.1.1.xsicompound   Delta_Mush.1.1.xsicompound   DeltaMush_sample.scn

The following is Guillaume's C++ implementation of Miquel's version, same nodes but performing faster and allowing attenuation of the effect by a weightmap. demo video and author downloads of the C++ version. Have a look at Guillaume's vimeo page including his 2014 showreel.

local backup: Delta_Mush.xsiaddon   Softimage_DeltaMush_SourceCode.zip

Bullit
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ICE Delta Mush

Post by Bullit » 08 Sep 2014, 02:28


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rray
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Re: ICE Delta Mush

Post by rray » 08 Sep 2014, 11:29

Also http://www.fxguide.com/featured/voodoo-magic/

Looks cool. For enveloping it looks like there's no big difference to selecting all points and hitting smooth in the weight editor.. but this works for all kinds of deformations
softimage resources section updated Feb 7 2019

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rray
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Re: ICE Delta Mush

Post by rray » 08 Sep 2014, 21:36

Raffael Fraggapane@ mailing list:
Delta mush isn't a smooth di per se', it's a binding state trick.
You smooth a mesh and save the delta of points from full detail to smooth
in the bind pose, you then deform and smooth out the full mesh, and lastly
re-apply the deltas back on the deformed smooth mesh to reinstate the high
frequency detail and irregularities.


A basic implementation like that is quite simple actually, and that's why
it's kinda brilliant.
softimage resources section updated Feb 7 2019

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rray
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Re: ICE Delta Mush

Post by rray » 24 Mar 2015, 18:36

Guillaume Baratte has done a C++ conversion of the compounds and shared them (plus sourcecode!) here:

C++ Implementation of Delta Mush for Softimage 2015
softimage resources section updated Feb 7 2019