Right arm of my character distorts.

Support Animation and Rigging
1

Heya.

I’ve been practising blender for over a year now, and I’ve gotten quite far into it (with a lot of spare time spent:cool:). I am using version 2.78a. Here is how my character looks when rendered:

Megumi1.jpg1366×730 206 KB

I don’t know why this happens, but underneath her right sleeve, whenever I rotate her arm clockwise, the arm distorts, but her left arm arm doesn’t. I can provide a couple more images to showcase the problem at hand.

Here is the right arm without rotating her arm (sleeveless):

Megumi2.jpg1366×729 307 KB

Here is the right arm when I rotate it clockwise (again, sleeveless):

Megumi3.jpg1366×730 302 KB

I have tried:
(1) Reordered the modifiers. Reordering either does nothing or makes it worse.
(2) Recalculated bones by “active bones” or “z+global axis”. Makes it worse by twisting the entire model!
(3) Checked if the vertex groups and weight paint for both arms is correct. They are identical since I used mirror modifier.

It’s strange how one arm animates fine (I tested her left arm by pasting the pose with a button) and the other doesn’t despite I’ve used mirror modifier. The mirror modifier isn’t the thing affecting it because when I remove it, I’m left with half the model which isn’t what I want. Pretty sure nobody would want half a character model.

Another strange thing is both of her legs animate really well and have no problems despite I used mirror mod on her legs too. Only the eyes are not mirrored because I used lattice cages for eye tracking which works really well. The arms and legs are part of one object by the way.

I hope I can fix her right arm so I can carry on with my character’s actions. Right now, I am in the middle of making a jump action. I’ve been able to make her wave with her left arm, so good job it wasn’t with her right arm waving!

People may be wondering “Isn’t the sleeve covering her right arm?” yes, but the sleeve also distorts a bit, because its taking influence off it distorting, so I need to fix her right arm. Thats the problem I need help fixing.

I have uploaded a short video of this character over on youtube if you want to see her.

2

Moved from “General Forums > Latest News” to “Support > Animation and Rigging”

Please post in the correct sub-forum.

3

Where is your blend file to look at? Please post one in here. http://pasteall.org/blend/

4

Hi.

My apologies for posting this in the wrong forum list. I haven’t used the forum for months hence the mistake. I’m guessing if I ever have anymore problems like this I have to post it under “Animation and Rigging”?

5

Um, sure alright, I’ll send a copy in here in a bit. Please read carefully the following points.

(1) I know theres a 99% chance you won’t do this, but please don’t steal my work. People say its very unprofessional to pass other peoples work as your own. This took me over 50 hours to make.
(2) I have read the blend file stays for about 5 months. Is anybody else able to download it in that time limit? I just want to upload it for you to debug whats wrong (unless somebody else would like to try fixing it).
(3) In the blend file, there are separate objects. Its best to hide the sleeves, then rotate her right arm by the blue circle clockwise and that is where the problem is.
(4) I have the bones on 2 layers, so you will need to go to the armature tab -> skeleton drop down -> toggle last bone layer.

6

One thing you may want to do (prior to uploading) is to simplify your rig to the point where all that’s left is the misbehaving part. By doing this, you isolate the part where you actually need the help (so we don’t get distracted by unrelated issues). It also reduces file size and prevents people from re-appropriating your work (if that’s a concern you have). And as an additional bonus, I often find that when I go through this process of isolating the problem, I frequently discover on my own the one thing that was causing the error (of course, if that happens, please still share the solution you found since other people may run into similar problems on their rigs).

7

I have simplified the model by making a blend copy and in that copy I have removed the collision and cloth physics, since that takes up a lot of memory. I have tried lowering the poly count by removing subsurf modifier, but it doesn’t lower the filesize for some reason, so I left that modifier in. The blend file is 2611K (about 2.5MB), so I believe that’s up loadable. Only thing is some blender users may not have strong PCs, because I have quite strong specs on my PC. I recently updated the graphics card and PSU to really strong ones.

Ok, I’ll upload it now.

8

Subsurf won’t change filesize, just RAM usage.

And when I say “isolate”, I mean in a big way… like deleting everything in the mesh and rig except for the arm.

9

The main reason I need the whole model there is because whenever I try any solution to fix her right arm the rest of the model breaks. I mentioned in my 1st post z+global axis breaks the rest of the model. I need to make sure any solution we find doesn’t break the rest of the model. In other words, the solution needs to prevent the whole model breaking as well.

10

Hi again.

I think we found a solution to the problem. Special thanks goes to “stilltrying” for finding the answer. They debugged what was wrong with my model, so I will paste what they said was wrong.

"Let me first state I don’t like this type of rig (of using mirror modifier). The reason is this style introduces what is called IK snap in weird places so you never get it right. It is when the mesh just jumps in your animation. UGH! I personally don’t rig a mirror mesh. Just me, but I’ve done a tone of these and it just gets your bone roll all messed up and the animators yelling at you.

But I can tell you spent a lot of time just trying to get this to work.
So… Here we go. I’m only going to do the right arm. You can fix the other one which also as issues.

  1. First of all hide everything but the body and the armature.
  2. Get rig of your basis shape key for now.
  3. Apply Mirror: (you don’t have to, but I find it really helps to get things organized).
  4. Turn off sub surf for now.
  5. Just quickly add a neutral color so your wire will stand out better.
  6. Make all vertices neutralcolor
  7. Turn wire frame on to see your topology.
  8. On armature turn on all your bones.
  9. Ok,on your forearm, you have 5 segments.
  10. On your topology on your mesh you have only four edge loops supporting your segments and they are not on your segments. So as your segments turn it doesn’t have enough topology to twist. Easy fix add a few more edge loops. I just added three. If I need more I’ll add it.

Ok lets first look at your bone roll. Z points the way x rotates on a positive axis. When people mirror bones, this gets all messed up. If you do this for yourself, not a big deal. You just do the opposite of what you do on the other side. Your rig will come back fast.

  1. So turn on your axis. Switch your view to normal. This will help if you use the widget. I usually switch to octoganal view on the bone and then switch back to test.
  2. You have your x axis up the way your elbow bends. Good.
  3. Your hand bone should align the same way. Into edit mode, select hand ik. r bone select forearm control N to active bone.
  4. Same with hand.r bone.
  5. OK. Let’s see what happened now. To pose. Do they twist hand open about 90 degrees.
  6. Click on your mesh and look at the topology. This shows you how the arm did the old twist.

Well there you go. Not bad without weight painting. Ok now you can work on the hand, and your weight painting and then on to your other arm which needs some attention here you go. I think this is what you want. If not let me know."

In other words, the main problem was I used mirror modifier which caused IK snaps, hence the arm twisting problem. So I will need to get rid of the mirror mod then reflect the topology of my character and connect the vertices correctly. Other problems was My edge loops on my character’s arms were not on the bone segments, so I will need to adjust the edge loops so the arms would twist properly. I will also need to fix the bone roll with “active bone”.

I will say this topic is pretty much resolved since we have a working solution, its just down to me following the procedure. I might come back here in case I discover something which might make it easier. or need further help.

Its strange how I need to get rid of the mirror mod since most Blender artists on youtube suggest using it!