Problem with RVK

Hi !

Until now, I only used RVK for facial animation.

I’m trying to create standalone characters doing simple tasks, for the Crosswalk project, and I have som problems.

I have found a lot of posts here, but always relating to facial animation.

I have set RVK for each part of the body that need to move: arm, forearm, head, legs… I have about 30 Keys.

The problem is that the groups ov vertices not only move as they were supposed to do, but each group is highly deformed during the movement.

When the character is looking down, the head inflates like a balloon !

Same problem when bending tha arm: the harm is deformed.

Rotating a hand, the hand inflates !

Is it possible to avoid these deformations ?

Any idea?

Tested under 2.36a and 2.37. on P4-2Ghz 1.5GB. Video cart Ati Radeon 9000.

Thanks in advance.

Philippe.

Hi Roubal! It’s not clear to me - are you using an armature too? Did you use an armature to pose? Had a problem with a test a while ago with poses still being stored even after the armature was deleted. Had to B box select in NLA and delete before continuing. Another problem I encountered was found by switching to Weight paint. While I had selected vertex groups to move - for some reason their sphere of influence was greater than intended, and also lead to weird results. Hope that helps…

I had similar problems too. Distortion with my RVKs and bone movements.

I fixed them by aligning the bones. Go to Object Mode. Select the bones and use the Ctrl+Shift+A combination. Then apply DEFORMATION.

It sounds like your X-Y-Z axis are not uniform or aligned correctly. press the “Draw Axis” button,and you may see what I mean.

Hi !

Thanks.

No, Im not using armatures. Only RVK.

I have not slept at all this night, thinking about this problem and some others.

I thought that it is not the good way to use RVK.

RVK works well for small displacements as used in facial animation.

My goal is to animate a character only with vertice displacement.

I wanted to create a ready to animate “universal character” with all possible movements already programmed in RVK.

Now, I think that I should use AVK instead of RVK. Maybe the RVK are not able to interpolate between 2 positions if the change is important and the distance too.

AVK should work, but I 'll have to manage differently, applying only the needed movement for each character, in a definite order and timing.

It is not as handy as RVK is, but should work better.

I also noticed something strange : RVK keys do not work after the key 30…

Did you see this trouble ?

Philippe.

You’re better off with an armature. It’s easy to goof-up the RVK and their additive properties…

Also, there is a limit on the number of RVKs you can apply in Blender (sad, but true…)

RVKs are for:

  • things like facial animation, where the movement is a bit more complex than bone animation can handle
  • fixing wierd deformations at strategic spots when using an armature

Also, and I don’t mean this cruelly, there’s no such thing as a universal rig. You can have a library of base rigs from which to start new characters, but each character will require careful tweaking (of vertex groups and RVKs) before it is ready for use…

Hope this helps

Hi !

Thanks !

Well, I use RVK, because they allow to create standalone characters, without armature or anythig else…

It is cool for an open project… send the character file, and the project manager has no more thing to do than putting it at its place !

Philippe.

It would be cool if armatures can be driven by sliders, like RVKs are, though. Just a thought…

For what I know, armatures can be driven by sliders. it is the NLA editor, but I’m not used to it…

One more thing to learn, but it is available.

For my own, I like Ipos.

Philippe.

I take the exact opposite approach. I don’t trust RVKs one bit. If necessary, I would even go so far as having one bone per vertex for facial animation at certain points. I reckon I could get away with 8 bones for the mouth, 4 for the eye brows, 2 for each eye (for the lids) and maybe 1 for the nose if I need flared nostrils.

Considering I have about 15 bones per hand, 17 for the face is not that bad.

I just like the fact I can grab a bone, move it, set an IPO and if it’s wrong, reset the bone or just delete it. All the time, I am aware of which vertices do what. It’s also much easier to animate rotational vertex changes like eyelids with bones.

I know armature posing is almost impossible in 2.37 due to performance but if you get one of the 2.38 builds from blender.org, you will see how much it has improved. They even fixed the weight painting under 2.37.

I definitely wouldn’t use RVK for the limbs because the rotations easily cause abnormal deformations. That’s what a hierarchical bone structure is for so that by moving the parent, the children follow suit exactly as expected.

AVK is even worse because you’d have to set keys for every single different pose.

Bones are so flexible because you set IPOs on them and create an action out of one or more of these. You can have as many actions as you like and then mix them all in the NLA.

Hi Osxrules !

I often use hooks, instead of bones, they are easy to use, but I noticed that they had a weird behaviour when parented to an other object moved by an Ipo : sometimes they follow with a one frame delay, or move only one step each two frames … I just remember the same thing using a bone though ! %|

The only reason that push me to use AVK and RVK is that it allows standalone characters without armature. Those characters are easy to share and use without any settings, in an open project. :wink:

Philippe.

Hi !

I have made a lot of experiments today, and here is the result.

I hope that you will find on these page some informations that could change your point of view on RVK and AVK.

http://3d-synthesis.com/example_no_particles.html

Tell me what you think about my approach of these tools, and feel free to add any suggestions.

Philippe.