PDA

View Full Version : Animating a snowman



Thomas M.
01-04-2008, 07:26 AM
Hi folks,

I wonder how to solve this. I need to animate a snowman. My biggest problem so far is how to turn the head independently from the chest. They are more or less two spheres positioned on top of each other. I can't figure out a way how i rotate the head without rotating the upper part of the chest. Right now I "solved" this issue with a weight map. So the head bones (parented to the chest bones) only effect the head, while the chest bones only displace the chest. That's great for rotating the head, but if I move the head forwards or backwards (/like looking to the ground or sky) the chest doesn't get involved, so it should be stretched in some areas to show the influence of the head movement affecting the upper body (shoulders, breast).

Without the weight maps the body gets twisted if I turn the head in it's heading.

To avoid twisting interaction I seperated the head from the chest.

Any ideas how to twisting while pushing and strechting is still enabled?

Although I'd like to know if anybody knows of a tutorial for IK fingers, while having also an IK hand.

Cheers
Thomas

THREEL
01-04-2008, 10:53 AM
Hey there Thomas,

I think if you have the weight map "fall-off" from 100% to 0% in the upper area of the chest, that should do the trick. In other words, if your entire head has a weight map of 100%, then the upper part of your chest can have the same weight map name ranging from 100% to 0% for where you want the head bone to quit influencing the upper chest.

As far as I know you can have more than one weight map influencing the same area, so your chest bone can have a weight map that covers as much of the chest as you want it to, even overlapping the upper part of the chest that is, also, influenced by the head bone.

Hope this helps!

tHREEL, but you can call me AL.

SplineGod
01-04-2008, 02:23 PM
Id use multiple bones much like you would do to twist a forearm. This will distribute the twisting in a more natural looking way and still keep the form.
Heres an example: http://www.3dtrainingonline.com/examples/bone_deform_example.zip

This is just bones with no weight maps.

evenflcw
01-04-2008, 08:21 PM
Yup. More bones is a good suggestion. Or maybe change the look and have the balls roll upon eachother!? :)

Why are you having problems with IK fingers? Do you want an ik chain from the shoulder down to each finger aswell as the hand? Use IKBoost. If you just want ik fromthe knuckles down to the fingertips for each finger just make sure you terminate the chains by activating Unaffected by IK of Descendants at the knuckles and each finger should become it's own isolated ik chain. Please explain more if you didn't get your answer yet.

SplineGod
01-04-2008, 08:27 PM
Ive never used IK on the fingers ever. Im curious also as to why you feel you need to. :)

Thomas M.
01-05-2008, 08:59 AM
Well, the hand is holding a product and it is a pain to move each bone of a finger to have the tip not penetrating the object. I never did animations, so rigging is something I'm not good at. to little experience. One of the things i do know though, is that Larry always proposes not to use weight maps. But in the end that will force one to use more bones to "stabilize" certain areas. So far there a three bones in the chest and head on top of each other like a spin. If I move an arm, it will also affect the outer parts of the chest. Bone falloff didn't seem to help. So probaly I need some ribs in this area to keep the arm from influencing these regions. I got this nice book about rigging at home (the one with the little cartton pig), but unfortunately I'm working in an other region right now.

Thanks for the tips so far. Probably someone will even come up with other ideas.

Cheers
Thomas

evenflcw
01-05-2008, 10:37 AM
You do realize that the choice to-weightmap or not-to-weightmap isn't exclusive. You can (and should) mix the two approaches to get what you want. You also don't have to create one weightmap per bone. You can assign several bones to use the same weightmap. This will allow you to isolate what bones deform what part of the mesh. Essentially masking of parts to be influenced only by a specific set of bones. In other words, atleast if you have branches for arms on that snowman (as opposed to arms made of snow united with the main body), you could try creating a single weightmap encompassng the whole arm and then just assign all arm bones this weightmap. Now the arm should be deformed exactly as before but not affect the chest.

Perhaps you could show us a glimpse of the model?

About the fingers. I remember someone posted a hand rig (I think on the old forum) where all fingers would curl around a bar (using ik and some expressions I guess).You move the bar around to to curl/uncurl the fingers. I think Pooby made it. If you want something like that perhaps try and ask him to post it again. But I'm only 70% sure it was him. :)

SplineGod
01-05-2008, 03:11 PM
Well, the hand is holding a product and it is a pain to move each bone of a finger to have the tip not penetrating the object. I never did animations, so rigging is something I'm not good at. to little experience. One of the things i do know though, is that Larry always proposes not to use weight maps. But in the end that will force one to use more bones to "stabilize" certain areas. So far there a three bones in the chest and head on top of each other like a spin. If I move an arm, it will also affect the outer parts of the chest. Bone falloff didn't seem to help. So probaly I need some ribs in this area to keep the arm from influencing these regions. I got this nice book about rigging at home (the one with the little cartton pig), but unfortunately I'm working in an other region right now.

Thanks for the tips so far. Probably someone will even come up with other ideas.

Cheers
Thomas

I never say not to use weight maps. I say to put in the basic bones and test deformations first and then decide if you need additional hold bones, weight maps etc. Adding weight maps and tuning them is a lot more tedious then adding hold bones which you can do immediately and see the results. You dont have an option to tweak weight maps in layout so going back and forth slows down the process. Since weight maps modifiy the standard bone influence it make sense to get a good understanding how bones work.
Bones also dont have to be placed into a character so that they visually look like real ribs etc. That can be oriented or placed anywhere.
Another advantage of hold bones is that you can see the results immediately and they can also be animated to help with deformations.

As far as posing fingers being tedious...welcome to the wonder world of animation. :) I can guarentee you that it will be much faster and easier to simply pose the fingers manually rather then try and setup some fancy rig which may or may not work for you. You can multiselect finger bones by right clicking on the root bone of each and then rotating them additively. After that you can fine tune how they grasp. IK wont let you individually tweak each finger bone if you have to.