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View Full Version : When to "not" freeze transforms?


b.Schulz
04-07-2003, 06:09 PM
In the case of blendshapes and modeling....when are you not suppossed to freeze transforms? I sometimes like zero'n things out whenever possible but I don't want to run into problems down the line if I freeze transforms on say blendshapes or other parts of the model. Definitly don't like double transforms. :scream: Curious.

ilasolomon
04-08-2003, 11:13 PM
. align all your blendshapes with the original mesh.
. freeze transforms of them all
. move aside the blendshapes wherever u want.

b.Schulz
04-08-2003, 11:32 PM
which is basically just like duplicating the head for example...then just moving it away? right? What about when modeling geometry in sections.....or when you group things?

Thanks!

ilasolomon
04-08-2003, 11:45 PM
ok, you want the original mesh be freezed transforms?
the possibility depends on the situation.
any actual examlpe?

b.Schulz
04-09-2003, 12:35 AM
no real example.....but say that I'm modeling a characters arms sep. from the body...then I will later attatch. Can I move the arms into position, then freeze transforms on them, even though later I'm going to do re-attatch it to the body. I'm gonna freeze transforms on the entire mesh anyways once its completely modeled right? What about random pieces of geometry that are say attatched to bones by parenting. ie....a button or something? Sorry.....I have no actual examples...just curious as to if there are any kinda known situations where you do not want to freeze transforms because it will mess things up.

-dc-
04-09-2003, 06:58 AM
You don't freeze transforms when you do the following:

model blendShapes
create IK handles
lock channels
channels have incoming/outgoing connections to/from other objects/expressions/etc


When modeling for rigging, keep in mind that an ideal model will be zeroed out with the feet centered at the ground plane. Generally, there should be no empty nodes in the scene, no history and no negative scaling. The only thing not frozen in the scene will be the blendShapes, but they are hidden, won't be bound, and are therefore not accountable for anything.

Regards,

Joe

:wavey:

b.Schulz
04-09-2003, 05:33 PM
Thanks!! :bounce: :D

b.Schulz
04-16-2003, 07:40 AM
What about Joints....say I put all my bones in place where I want them, and they are rotating correctly...then would I want to freeze Transforms on them?? Or do I never want to freeze transforms on them?

MDuffy
04-16-2003, 09:07 PM
The best way to judge whether you should freeze transforms or not is to know what freezing does, and know if something needs to be frozen or not.

You only really need to freeze transforms on objects that A) need to be animated, and you want their base pose to be zeroed out, B) you need to do a calculation off of the channels of an object and you want those values zeroed out at a given point to make the calculation easier, or C) you need to set the zero position of a node so you avoid gimbal lock when it is animated.

If you are parenting geometry to a bone and you won't be animating that geometry directly, then there's no reason to freeze it. There's no reason to freeze transforms on morph targets (and if you do it will probably break them). Often your various groups in the rig don't need to be frozen.

When you freeze a transform, it simply adjusts the rotate/scale pivot location and zeroes out the channels. When you freeze something with a shape node (mesh, spline, nurbs, etc) then the new position is baked into the geometry itself; all your vertex positions will be updated. This is what causes blendshapes to break when you freeze them. When you freeze a bone, it adjusts the rotation values in the joint orient field. You can't always freeze out the transforms in a joint.

In general, I avoid freezing geometry during the setup process. If I have to animate the geometry then I parent it to something else and animate that parent. This makes it easier to switch out geometry at a later date too. I freeze out control splines so that their base pose is zeroed out. I freeze out bones if I'm animating them directly or I'm constraining them to a zeroed out control. Sometimes I avoid freezing stuff by aligning a parent transform node in the "frozen" direction, and then when the child is parented under the parent and facing the same direction, its channels are naturally zeroed out without having to have anything baked in.


Hope this helps,
Michael Duffy
mduffy@ionet.net

b.Schulz
04-16-2003, 09:59 PM
Thanks....that does help. So really I only need to freeze transforms on like joints that I want to keep their position but I want to make it the base position, or zero'd position. It makes sense now.

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