determining segment lengths for the skeleton in Arena

[digitizer]

I am trying to improve the quality of my captures by adjusting the segment lengths of my skeleton in Arena.

Basically, after measuring my subject, the measurements seemed marginally effective in improving the quality of the take. Instead eventually I just started 'eyeballing' the lengths and that seemed to give me a little better results!


I have a few questions:

- How is it that the software wants to know both the shoulder-to-shoulder distance...then later in the wizard it wants to know the individual length of each shoulder? Is the measurement for the shoulders from the center of the sternum to the center of glenohumeral joint? If so, isn't the shoulder-to-shoulder distance going to be twice that number? Or are the 2 measurement meant to be done differenty?

- When highlighting the body segments in Arena, some segments include either a proximal or distal attachment. The shin segement appears to include the knee joint. Is the model designed to include that joint when I take my measurements? And should I include that whole joint (or just up to the center of the joint)?

- Increasing the length of a segment (for example, the upper arm) doesn't seem to modify the location of the joint between that segment and the next one down the chain (e.g., the elbow joint). I extended the upper arm to an exaggerated proportion, and the elbow joint stayed where it is. What constitutes a change in joint location and can this be achieved by modifying the skeleton?

Overall, I would be thrilled to see either a tutorial and/or some more explanation of the process of developing and fine-tuning the skeleton. I wish my kinanthropometry skills were better...so it would be time-saving to know considerably more about how Arena expects the body segments to be measured!

Maybe I might be so bold as to recommend:
* Similar to the marker placement wizard, how about a screen-by-screen prompt for each body part, describing exactly where the distance to be measured is? Center of joint to center of joint (?)...whether it is to be measured vertially or horizonally (like the torso...I originally measured it horizontally), etc, etc.
* Options for inches in all input fields


Finally, is it just me, but I noticed that the check box for the Symmetry function did not apply any effects.

Thanks for your support!

digitizer

[Jim]

Hello:

Thanks for the questions and suggestion. We are a bit shy on the documentation front and we need to address this, it is somewhat of a challenge as we are improving the software daily. Still, I will have one of the programmers form a more detailed response.

[digitizer]

Hi Jim,

Any word from those programmers yet?