Determining the Position of Wrist (and others)

[CFJH]

Hello,

In my povray development I need to get the exact position of the wrist after modelling and posing a model (e.g. to apply a watch to the wist).

Currently I'm trying to parse the skeleton (seperatly exported do a .bvh-file). I'm using the "default" skeleton. My problem is, that the model doesn't match to the skeleton after modelling (changing the height and other properties).

How does the modelling change/modify the skeleton, how can I re-implement this in a script outside makehuman ?
Hoe can i determine the exact position/orientation of wrist, neck, ankle (...) ?

[joepal]

My suggestion is to not go via the skeleton.

The base mesh (actually also the proxies) has fixed vertex indices. That is, you can know that vertex 3898 is placed on the inside of right arm's wrist.

On the wrist, you can pick a bunch of vertices on the circumference, calculate the mean position and from that conclude where the lower arm bone's tail is.

This will work irregardless of what skeleton or pose you use.

A slightly more advanced way is to go for the joint cubes. These are hidden geometry which should coincide with the head/tail of all bones in the default rig. If you look in the base mesh's source (https://raw.githubusercontent.com/makeh ... s/base.obj), you can see that there is for example a "joint-r-elbow" group. The mean of the positions of the vertices in this group is the elbow joint. However, this requires that you imported the mesh including helpers, which might be cumbersome for other reasons.

As a side note, Blender has a python function for figuring out where a posed bone is. A PoseBone's properties "head" and "tail" are always the world location of the start and end of a bone. But I have no clue if you have a similar function available somewhere in your pipeline.