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View Full Version : Bones and Skelegons - Looking for answers



MiniFireDragon
06-24-2004, 07:18 AM
I posted the following message in Tips and Tricks and got 2 people to respond, so maybe I am posting at the wrong spot, here it is again:

I want to try and get all the questions I have about bones and skelegons into one place. These are for version 8.

1: When you draw skelegons in Lightwave Modeler, then rotate them, the skelegon also rotates on it's bank. Does this effect the way the bone operates in Layout?


2: What direction is best for rotating?? Heading? Pitch? Bank?

For instance, an arm, pivoting on the elbow. Do u want to use pitch or heading to rotate it? I know that "twisting" is best for the bank.

From CommonGrafx:
As layouts system using pitch for muscle flex and the like, it is said that pitch would be the optimal axis to rotate things on when you want to make use of these tools


3: That blue dot in Lightwave 8 represents the bank direction. I assume it is pointing in the 0 direction. What direction should it be facing if I am going to use it for questions #2? I ask because the only place it really matters is when you are using local coordinates for the parent and local/parent for the child, correct?.


4: Do you want to use bones in Local, Parent or World Coordinates?


5: Weight Maps - though they aren't all the time needed, when they are is it best to just do a length? Like an arm and not break the arm into up/lo arm, hand. Or is it more for how the model reacts to the bones??


Additional notes beyond the initial questions:

CommonGrafx:
It is always a good idea to prebend joints slightly to help the IK solver know which way the joint is to bend.


Also, for the moderator, is it possible to make this a sticky??

bloontz
06-24-2004, 08:42 AM
I think you will find that those answers aren't etched in stone, especially #5. Timothy Albee's book Lightwave 3D 7 Character Animation does a decent job of explaining his ideas on the subject and should shed some light on the matters for you.

MiniFireDragon
06-24-2004, 08:55 AM
I am not looking for etched in stone, I am looking for other peoples "hey this is what I do".

bloontz
06-24-2004, 10:17 AM
Okay, but I still recommend that book.

My opinions

1. Yes the skelegon rotation via the bank handles will dictate how the bones are initially converted in layout but you can change that in layout after the fact.

2. You generally want to avoid situations where you have gimble lock, when a rotation axis becomes aligned with another essentially eliminating an axis of rotation. As pointed out by Uncommongraphics the fact that Layouts bone deformation corrections work along a specific axis makes the orientation important.

3. I suppose that depends on which direction the deformation will occur.

4. I would generally use parent with a character, that way if you rotate say, a knee the ankle will still have it's rotation handles alligned with the ankle.

5. If you set up the bones carefully you can get away with a minimum of weight maps or none at all. Often you can just use enough to isolate areas where the deformation is bleeding into an adjacent area. For instance if moving an arm deforms the chest using a single weight map for the entire arm can help correct that.

ursa
06-24-2004, 12:19 PM
you'll also want your limb rotations to use the pitch channel, cause this is the only channel that works with muscle bulging and joint compensation features.

UnCommonGrafx
06-24-2004, 01:49 PM
Like I've said, Minidragon,
This is a thing that is passionate, has many players and everyone of them is RIGHT for their own reasons. When it doesn't work, it's because they've now learned they are not so right.

What's my point? Tag on to this thread for a Rigging Ride!
A fun jaunt into the minds of LWRiggers @ Spinquads.
http://tinyurl.com/2ztgm

Thought you'd wanna tag on...