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Why do bones do this?
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Why do bones do this? // Archive: Tech Forum
Post by GrimMoroe // Jul 6, 2007, 5:51am
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GrimMoroe
Total Posts: 50
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I really don't understand the thought process behind the way bones create a messy junction when branching. I don't care much about how it looks but it makes weight painting to get desired results around the hands and fingers a pain. in this first example is how other apps do bone branching which makes weight painting a snap.
http://i69.photobucket.com/albums/i60/GrimMoroe/OtherBoneS.jpg
The green lines show how I built the skeleton and if you look just under that you can see the mess of bones.
http://i69.photobucket.com/albums/i60/GrimMoroe/WTH.jpg
This is not a rant I would just like to know from one of the Dev's why this approach was used....I mean is there a reason for this? |
Post by trueSpaced // Jul 6, 2007, 6:38am
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trueSpaced
Total Posts: 544
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I don't think you can have bones branching off of a joint like that... I was never able to do that. It would always do what yours is doing. Idk if it's supposed to though, anybody else know for sure?
-TrueSpaced:banana: |
Post by 3dfrog // Jul 6, 2007, 7:11am
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3dfrog
Total Posts: 1225
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For the hand I think truespaces way of handling the bone is actually better. When you click the joint and then add your next joint it adds limbs to the bone, but it is easier to weight paint and control because it actually works as one hand bone. This may not be practical for other purposes though. Maybe if there was a way to choose if you want to create a limb off a bone or create a brand new bone stemming from that joint that acts seperately. In animation master you would handle it by having your hand bone, and then create the fingers as children of the hand bone without actually having them attached to the hand bone, so you can move the hand, and the fingers move with it, but are not physically attached. If truespace could adapt something like this with the bones it would be ideal, but maybe they have other plans for the bones. |
Post by trueSpaced // Jul 6, 2007, 7:24am
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trueSpaced
Total Posts: 544
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I actually think that TrueSpace's way is better in this case because it avoids weird deformations in the hand itself. If you attached the hand to the bones in the other 3d app and tried moving the bones that are different in TrueSpace, a section of the palm of the hand would be deformed and bend weird. If you look at your hand's bone structure, it resembles the TS one more than the other one. So long story short, I agree with 3dfrog.
-TrueSpaced:banana: |
Post by GrimMoroe // Jul 6, 2007, 8:54am
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GrimMoroe
Total Posts: 50
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If you look at your hand's bone structure, it resembles the TS one more than the other one. -TrueSpaced:banana:
This statement is not correct.
So lets have a look at the bone structure in the hand and see.
http://www.pncl.co.uk/~belcher/handbone.htm
I spent the last year studying anatomy.
If you attached the hand to the bones in the other 3d app and tried moving the bones that are different in TrueSpace, a section of the palm of the hand would be deformed and bend weird. -TrueSpaced:banana:
In the other app the hand deforms perfectly so this is also incorrect.
I might add that if the first way of doing it is bad then why does every renowned animator/rigger do it that way?
The reason I don't like the way TrueSpace is doing it is because it makes it hard to cup the hand properly on a high resolution model, if your hand deforms improperly then you have set your rig up wrong.
I don't mean to come across as nasty, but I have had the privilege of learning from some of the best in the industry and what you say is inaccurate. |
Post by TomG // Jul 6, 2007, 9:00am
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TomG
Total Posts: 3397
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You can still achieve what you want though - effectively what you want is a finger bone that runs through the hand itself.
So simply do exactly that :) Start your branch right at the wrist, and add an extra bone onto the fingers that way, which runs through the main body of the hand.
HTH!
Tom |
Post by 3dfrog // Jul 6, 2007, 9:05am
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3dfrog
Total Posts: 1225
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yes that first one is more anatomically accurate, and I see what you mean about using that structure to cup the hand, I never thought of that. I guess joint limits could add enough constraints to deform the hand bones right, but I don't see a way to add those bones in truespace. But there is good news, I just recieved an email from Tom Grimes stating that sub skeletons are actually possible in truespace. Hopefully they will post that technique here soon. Maybe that will help solve that problem. |
Post by GrimMoroe // Jul 6, 2007, 10:24am
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GrimMoroe
Total Posts: 50
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You can still achieve what you want though - effectively what you want is a finger bone that runs through the hand itself.
So simply do exactly that :) Start your branch right at the wrist, and add an extra bone onto the fingers that way, which runs through the main body of the hand.
HTH!
Tom
I tried this tom and still ended up with the same results unless I am missing something. |
Post by tomasb // Jul 6, 2007, 10:44am
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tomasb
Total Posts: 261
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there are several reasons why this kind of branching was used:
1) from anathomy point of view: joint always connects 2 bones. You cannot have multiple bones going from one joint... there always need to be some space between that bones - which is in fact another bone. So you get bone with multiple joints which are attached to multiple bones...
2) UI: when you have one outgoing bone, it is much simplier to visualize limits in which joint works. You always have two bones sharing one joint and you can see it directly... With multiple bones going from one joint... there is not an easy way how to setup joint limits...
3) with tS current approach, you can get the other approach by creating small bone with multiple joints and then add bones you want... |
Post by TomG // Jul 6, 2007, 10:46am
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TomG
Total Posts: 3397
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You end up with this bone with the branches, but it is moved to the wrist, and you have an extra bone ("before" the finger) created.
So old method - click wrist joint, click base of thumb, then click down thumb; choose wrist joint, click base of index finger, click down index finger; repeat. This gives a branching bone in the main area of the hand.
New method - click wrist joint, click next to wrist joint for the thumb (still at the wrist and well before the base of the thumb), and then click base of thumb (gives extra bone running through the hand from wrist to base of thumb), click down thumb as before.
Now select wrist joint, click next to wrist for index finger, then click to base of index finger. Same thing, gives extra bone running through the hand.
See attached - left is old method, right is new, giving you the bones to curve and cup the hand.
It doesnt look the same as the other application as it is branching from the joint and we branch from the bone, but it should give you the same functionality :)
HTH!
Tom |
Post by trueSpaced // Jul 6, 2007, 1:32pm
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trueSpaced
Total Posts: 544
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Sorry GrimMoroe, I understand what you're saying now, for some reason I thought that the joint that all of the fingers connected at in the other 3d app was the palm of the hand.... Sorry for the misunderstanding.... :(
-TrueSpaced:banana: |
Post by GrimMoroe // Jul 6, 2007, 5:56pm
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GrimMoroe
Total Posts: 50
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Sorry GrimMoroe, I understand what you're saying now, for some reason I thought that the joint that all of the fingers connected at in the other 3d app was the palm of the hand.... Sorry for the misunderstanding.... :(
-TrueSpaced:banana:
No harm done. I hope I didn't come across to harsh...I didn't mean to. :)
tomasb- Thanks for the explanation.
TomG- That will work thanks. I must say though that creating a bunch of extra bones means more rotation locks and weight painting which = more work. It just seems very counter productive to me...I could be wrong because this is just my opinion. |
Post by trueSpaced // Jul 7, 2007, 12:16am
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trueSpaced
Total Posts: 544
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You weren't it's all good here too:)
-TrueSpaced:banana: |
Post by 3dfrog // Jul 7, 2007, 7:29am
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3dfrog
Total Posts: 1225
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The bone that the limbs come off on where it looks like the bone is breaking into seperate bones actually acts as one bone in animation. All you have to do with that is put a rotation lock on it and no need to vertex paint it. But you still have those hand bones. The hand bones won't be generating exactly from the wrist so it won't be as exact as the image you showed for the other app. |
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