Free Harmonic Deformer for Maya

[matt estela]

(crosspost from another list)

Last week, Toolchefs released a free harmonic deformer for Maya.

Here is the link if you want to have a look:
https://www.toolchefs.com/?portfolio=harmonic-deformer

[Steve Davy]

What's the advantage of this over Maya's wrap deformer?

Is it faster, maybe? Certainly the wrap deformer ain't speedy.

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From: ma...@tokeru.com
Date: Thu, 23 Apr 2015 08:01:03 +1000
Subject: [maya_he3d] Free Harmonic Deformer for Maya
To: maya...@googlegroups.com

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[matt estela]

Skipping to the end of the pixar paper this is based on:

"We have shown that harmonic coordinates offer an effective character articulation method that improves on previous methods in several ways. First, harmonic coordinates are non-negative, and their influence falls off with distance as measured within the cage, leading to intuitive behavior even in strongly concave situations. Second, harmonic deformations offer greater topological freedom in crafting control cages. Specifically, arbitrary linear cell complexes can be used where necessary to more precisely control the interior nature of the deformation."

So its more like using a FFD lattice than a wrap, but you can make the base shape in a fairly arbitrary shape rather than just a box, its fast, and the results are predictable.

[Simon Yuen]

Actually, its quite a bit more than FFD.  Its "like" FFD but there are a few things that makes this Harmonic give better results.  FFD just has a linear interpolation on how the driven mesh follows the FFD cage, so if your cage is not preserving volume lets say, its very easy for the underlying mesh to shear or loose volume.  Harmonic is not linear and is not a simple direct 1 to 1 drive of the underlying mesh.  So even if your cage is not deforming super nicely or pulls to more extreme, the underlying mesh does not easily shear or loose volume.  That is where the expensive calculation comes in.  Also the weight distribution of driver point to driven mesh is very different from FFD.  Quite a bit more complicated.

[Steve Davy]

In practical terms I'm still none the wiser! I think it would behoove Tool Chefs to offer a side by side comparison of their tool with other methods, or at least offer a more complex example. Just from their simple example demo, I don't see anything that would make me want to bother installing this.

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Date: Fri, 24 Apr 2015 10:43:09 -0700
From: syuen...@gmail.com
To: maya...@googlegroups.com
Subject: Re: [maya_he3d] Free Harmonic Deformer for Maya

Actually, its quite a bit more than FFD.  Its "like" FFD but there are a few things that makes this Harmonic give better results.  FFD just has a linear interpolation on how the driven mesh follows the FFD cage, so if your cage is not preserving volume lets say, its very easy for the underlying mesh to shear or loose volume.  Harmonic is not linear and is not a simple direct 1 to 1 drive of the underlying mesh.  So even if your cage is not deforming super nicely or pulls to more extreme, the underlying mesh does not easily shear or loose volume.  That is where the expensive calculation comes in.  Also the weight distribution of driver point to driven mesh is very different from FFD.  Quite a bit more complicated.

[matt estela]

Heh, totally SImon, the results look much nicer, and there's fancy maths stuff going on under the hood, I was more focusing on what the most analogous existing deformer is for an end user.

Steve, a good use case would be where you'd normally think twice about using a wrap. Upressing a cloth sim for example; sim with lo rez, model up a high-rez version, and harmonic deform the high to follow the low. Similar for driving a high res character mesh with a fast low res rig. 

[Steve Davy]

As a mostly matheist, I appreciate the dumbing down! ;)

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From: ma...@tokeru.com
Date: Sat, 25 Apr 2015 09:21:43 +1000

Subject: Re: [maya_he3d] Free Harmonic Deformer for Maya

To: maya...@googlegroups.com