Pose Position vs. Rest Position Problem (using Blenrig)

I’m applying Blenrig to a character, and I’ve gotten to the tweaking bone positions step. My gorilla-proportioned character is wildly different from the basic Blenrig model, so a lot of the little control bones have drifted quite dramatically from their correct positions.

The problem I’m having is that after fiddling these little bones into place in edit mode, I go back to Pose Mode and they’re still wrong, but usually in some creative new way. In Rest Position, they’re exactly where I put them in Edit Mode. In Pose Position, they jump all out of alignment. I thought perhaps I had put my model into a pose and failed to clear it, but that is not the case. If I understand correctly, if I have not yet actually posed the armature at all, Pose Position should start out identical to Rest Position, right? What’s going on here?

For example, here’s the elbow in Rest Position, with everything exactly where I put it in Edit Mode:


…and here it is in Pose Position, with all location, rotation and scale cleared:


Again, shouldn’t those two pictures theoretically be identical?

Unless I’m mistaken, it looks like there are two bones in the upper arm and you’ve only moved one of them in Edit Mode.

OR

You cleared the poses on one of the upper arm bones, but not the other.

I’ve never used BlenRig, so I’m only going by experiences with other rigging tools.

Nope, the Rest Position is identical to edit mode positions. Also, I’ve cleared everything. Select all, clear all. It’s just switching between rest and pose that does this.

You didn’t mention that you checked BOTH upper arm bones which was my point. Is that the case?

Yeah, I have cleared all transforms from all bones, and aside from bone colors, the positions in edit mode are identical to those in the first picture above. Here, maybe a .blend will make things easier. You might need to install the blenrig addon, which is here.

Well, going back and forth between Edit Mode and Pose Mode with Armature > Display > Axes turned on, all the bones in that area look to be in the same orientation in both modes.

The only difference I noted was that with bone shapes assigned, they look different in Pose Mode, but that’s just a cosmetic thing and won’t affect operation of the rig.

The arm.L and arm_twist.L bones are lined up perfectly for me. Mind you, I didn’t install BlenRig, so I was looking at the generated rig by itself. Maybe there’s a difference when BlenRig is installed.

It’s not just a cosmetic quirk, it’s actually affecting the shape of the model. Some of the misaligned bones are deform bones, so they’re squashing the arm in funny ways. Take a look:


Here it is in Pose Mode, rest position. This is fine. The bones are all aligned, they’re all identical to their positions in Edit Mode, and the model itself is in the right place. I’ve drawn a red line with the grease pencil to show where the arm is in this position.


Now I’ve just clicked Pose Position. My grease pencil line is still in the same place, but see how the arm has moved?

At this point I’ve only repaired the alignment of the bones in the arm down to the elbow. I’ve got the wrist, hands, neck, head, torso, hips, legs and feet still to go. If it’s doing this to the arm, who knows how the thing is going to look when I finally finish it! I know this is probably something simple I’ve messed up, but I just can’t figure it out. I’m tempted to switch to Rigify or just build my own rig from scratch, but I need to handle a bulky, muscular body, and Blenrig otherwise seems like the best solution for that. Does anyone know what I’ve done wrong here?

Sorry, Wanderdragon, I’m out of ideas. Having never used BlenRig, I’ve exhausted my applicable general knowledge.

Perhaps you could find out more on the BlenRig website. If your problem isn’t mentioned specifically, there’s a Contact link and you can ask the guy who designed it.

I think Rest Position overrides constraints to snap back to edit mode position. In Pose Position the constraints turn on and will move bones according to bones they are constained to.

Very small misalignments or roll settings can get magnified further down a chain of bones.

I rigged a skeleton IK/FK with 1 bone per vertabrae controlled by 2 spine control bones. Long story short… I had issues with jumping hands because of a few bones way down in the spine. There was just a little jumping around the shoulders but was hardly noticeable until I really looked hard. Actually the bones there didn’t really “jump” at all, they just moved like… a pixel.

You probably should check everything from the root up. Or you can do like I did and spend days tweaking on it top down before ending up checking everything from the root up anyway. (Not fun).

I went through the whole chain and did much snapping with 3D cursor to get all bones lined up exactly and much Ctrl-N > Active Bone to get all bone rolls exact on the money. That’s what it took to fix the jumping bones problem in my rig.

You may have better luck building your own rig from scratch but if you can troubleshoot and fix the complicated rig you have there it will greatly advance your rigging skills. You’d probably end up doing lots of the same tweaking on your own rig.

Hope this helps.

-LP

I see this often but it never seems to make a differance on my deforms. Has it made a differance on yours?. If not then just plug on with your work.

@joeblades: Yes, it has made a difference on the model’s deforms. See the illustration above with the red lines to show where the arm goes. It’s not just the position though, it’s the actual shape of the arm. It squashes laterally a bit with that odd bone dislocation.

@LarryPhillips, I think you are right. It does seem to be the result of mismatched rotations. I’ve decided that for a few reasons in addition to this rigging problem, I need to go back a few steps.

I’m going to take advantage of the rig as-is and change the model’s pose to a standard T-stance with the arms outstretched, then apply the modifier, delete the whole rig, sculpt out the few nitpicky odd mis-deformations, then re-rig it from scratch. If it’s closer to the original rig’s basic shape, I should have fewer (though of course never zero :p) problems with it. I think I made things harder than they needed to be by modeling the character in a quarterback pose to begin with. Besides, I could always use the practice, and I’m not on a deadline, so there’s no harm in starting over.