Default Rig Technical questions

[C_Man]

Hi,

I have really enjoyed the ability to very quickly create characters with good topology with Makehuman with subsequent tweaks in Zbrush and 3ds Max. Thanks to all in this community for generously supplying such an excellent set of tools. So far, in my experience the default skinning of the mesh generally works well in the normal range of motion.

My questions:

1. I am looking for the overall design logic of the default rig in v1.1.1. Is there a background document that explains the logic behind the joint heirarchy and intended purpose of the various joints? For example why are there 2 bones for the upper arms (upperarm01.L + upperarm02.L) with different pivot points? The upperarm01.L appears to be located in the traditional shoulder joint location while the upperarm02.L is a bit further down the arm. The same is true for the lower arm and both the upper and lower legs. After reading the available documentation and searching the forums, I could not find any documentation of the logic behind this. This is not a complaint by the way, I am simply trying to use the rig to best advantage in animation.

2. Why are there 3 neck joints?

Thanks in advance for any help in gaining a better understanding of the intended purpose of the individual bones in the default rig.

[brkurt]

Hi,

I have really enjoyed the ability to very quickly create characters with good topology with Makehuman with subsequent tweaks in Zbrush and 3ds Max. Thanks to all in this community for generously supplying such an excellent set of tools. So far, in my experience the default skinning of the mesh generally works well in the normal range of motion.

My questions:

1. I am looking for the overall design logic of the default rig in v1.1.1. Is there a background document that explains the logic behind the joint heirarchy and intended purpose of the various joints? For example why are there 2 bones for the upper arms (upperarm01.L + upperarm02.L) with different pivot points? The upperarm01.L appears to be located in the traditional shoulder joint location while the upperarm02.L is a bit further down the arm. The same is true for the lower arm and both the upper and lower legs. After reading the available documentation and searching the forums, I could not find any documentation of the logic behind this. This is not a complaint by the way, I am simply trying to use the rig to best advantage in animation.

2. Why are there 3 neck joints?

Thanks in advance for any help in gaining a better understanding of the intended purpose of the individual bones in the default rig.

If you scroll through my posts, you'll see many of the same questions, and a few answers.

(1) Normally, if there are two upper arm bones (for example) that indicates that one of them was intended to be forward kinematic, the other inverse kinematic. That would be a solution for the muscles of the forearm. (Believe it or not, way back in 1998 a biomechanical engineer created shape keys to solve that problem, but not much came of it.) The same with quadriceps twists on the upper legs. So, my understanding is that the default rig was intended to have its own interface, where the uniqueness of the rig would be hidden from the use.

(2) As for two neck bones, I'm thinking that you are looking at an unfinished interface. Where things really get interesting is in the bones that control the facial muscles. I completely agree with the 'what' of those bones, but not the 'how'. For example, if you free transform and rotation of the eyebrow bones, apply IK to the innermost eyebrow bone, it makes for terrific poses. But then, whatever interface that was supposed to work with it doesn't.

I hope that helps; I've left lots of Blender models that you can download, and compare the default rig to the ones I've designed.

[C_Man]

Thanks for the prompt reply, brkurt. I will have a look through your posts for any more info that is available. One of the things I am working through is the best mapping of motion capture data to the MH default rig bones. It looks to me that the bone designated as 01 at the end is generally the correct one to use for upper and lower arms and legs based on joint location.

So far, I am a real fan of the facial bones in the rig. They really help in the creation of morph targets for facial motion capture. Thanks again.

[joepal]

Unfortunately, the people who designed the default rig have moved on to other projects and no longer follow these forums. So an in-depth explanation of the reasoning might be hard to get.

[C_Man]

Unfortunately, the people who designed the default rig have moved on to other projects and no longer follow these forums. So an in-depth explanation of the reasoning might be hard to get.

Thanks joepal, for letting me know. If I come up with any useful insights as I work with the rig, I will post them.

[brkurt]

Unfortunately, the people who designed the default rig have moved on to other projects and no longer follow these forums. So an in-depth explanation of the reasoning might be hard to get.

Thanks joepal, for letting me know. If I come up with any useful insights as I work with the rig, I will post them.

That's why I had to do a custom rig. However, my focus is strictly on stop-action and poses; morph targets (Maya) and shape keys (Blender) don't make it through an Open Collada export, which is the most reliable one for Marvelous Designer.

I'm told Mudbox fbx is loaded with 'proprietary gotchas', so I'm not interested in exploring that approach. The goal is a complete work flow: MH --> Blender -->MD (with a detour through ZBrush)-->Blender --> Cycles (or Yafaray, because it's so darn fast).

[C_Man]

Is there a python script or some other means of renaming the bones in the default rig no toes for export? One difficulty I am having is that many of the 137 bones in the default rig use the period "." in the name which wreaks havok in other applications. (The name of the bone is misunderstood to be the string before the period and the period is interpreted to be the start of a property or function). I really only need to replace the period with an underscore for all bones that use the period in the name. Any insights on how to automate this process would be appreciated.

Thanks

[C_Man]

I figured out a workaround for the bone naming issue by writing a search and replace script in another application (i.e, after export of the Makehuman default rig via fbx.