Vertex Association (better Skin)

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Old 02 February 2013   #1
Vertex Association (better Skin)

I'm trying to think of a way to better associate vertex with bones.

In my mind a user would want to find the closest vert to the center of each bone and then grow outward like max does when you have a vert selected and you hit "grow". But at the same time take into account the normals and verts that may be closer in distance to other bones.

Here is a theory:
1. Find a vert closest to each bone.
2. From that vert count the length of each edge to corresponding vert outward to the next verts assigning them to the next closest object but also take into account if the vert is being used already by another bone.

I've attached a scene for testing.
An a screen shot for what I'm after.

Not saying the method is the best method, but I'd love to get anyone is who interested and figure out a better method for a tool we can all use and build upon.

Maybe some sort of heat map like maya, but for max.
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John A. Martini
Old 02 February 2013   #2
i don't want to disappoint you, but your concept is kinda old-fashioned. in modern rigs a skin bone usually doesn't have a size, and in some cases its position might be also abstract.
for example...
the twist forearm skin bone. it's constrained by orientation to two controls and might use the third one as an up vector. its size doesn't really make sense. its position might be anywhere but in-between forearm and hand joints.
how much information do you have from this bone to make 'auto-skin'?
Old 02 February 2013   #3
I see what you are saying.

I just wanted to get a brainstorming thread going to possibly come up with a method for generating a better 'base' skin than the one that is currently being generated.

How does the heat map methods work? Is that the next generation 'say' for generating a base skin?
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John A. Martini
Old 02 February 2013   #4
I'm not sure if there's any parallels because this is more of a skin weight tool than what you're asking about but this plugin's relax feature seems to take really lousy weighting and do a great job auto-fixing it.

Anyway, I'd imagine using this together with heatmap would make character skinning a pretty painless process.
Old 02 February 2013   #5
good idea about brainstorming this Joker, But I am one of those who does not think that the skinning process we have now is that bad :P ( I am gonna get hate for this ) could be better ? yes, but at least max offers A LOT of tools for us to transfer skinning between models that have been modified or scaled or had bones moved ! I honestly just wish we had a weight hammer and better painting tools for it.
Felipe Nogueira aka: PePeTD
Technical Artist/Character TD
Old 02 February 2013   #6
Thanks for the input Felipe. All in all I do not believe the skinning is that bad either. Just the initial skinning that is created when the skin modifier is added along with all it's bones. I wish that base skinning would be more intelligent. As for painting tools, I'd love to hear more in depth of what kinds of painting tools would you like to see for max?
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John A. Martini
Old 02 February 2013   #7
I'm sure you've seen this but just in case :-

I do agree that skinning could be more intelligent. Hands and fingers are always dull to do, bone envelopes inside one finger affecting the next finger could surely be avoided in the 21st century....
Renderfarm hire available @
Old 02 February 2013   #8
Thanks Andrew,
I've seen that and tried that. It works alright for the most part.
It does calculations just base on distance to the center of each bone and then weights accordingly. It's a great tool, but I think there is a another step up from that.
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John A. Martini
Old 02 February 2013   #9
Sorry for the delay John. I think Max's painting weights tool could have a better pressure sensitivity when skinning a character. I also find that the blending is very arbitrary the same goes for the *Smoothing* in Maya. It is not hard to create an algorithm that properly smooths verts it doesn't need to be perfect it just needs to do a better job than what we have, I just find it funny that to this day you can blend or smooth your verts and have them end up worst then the starting point with completely arbitrary weights to what you had before.

Besides those points I do not have a problem with skinning as I said before I learned to work around these issues and they do not really affect my skinning workflow. I do no think there is a real solution to this problem John, characters can range from a variety of shapes and forms that while a solution would work for one character it would not work for another.

@hotknife ever tried skinning the fingers 100% to the wrist and then going finger by finger adding the proper weights? Finger are the easiest to skin IMO. the biggest problem i have are with things like straps.
Felipe Nogueira aka: PePeTD
Technical Artist/Character TD
Old 02 February 2013   #10
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