First I want to say that I'm very motivated to improve this part of the application
1) what inertial parameters (i.e., segment mass) do you use to estimate total body center of mass location for the "human model"? Dampster? De Leva? Etc..
I thought I had put a comment inside the XML to document the source but apparently I must have forgotten… Unfortunately at the moment I can't find the exact reference I used for the coefficients. It might have been from a book annex.
Please point to popular models that are used in your field and we'll build the corresponding tools. I want the user to be able to pick between several models anyway.
2) I might have missed something but...why I cannot modify the size (i.e., segments length) of the "profile" model?
Yeah the profile model is a bit restrictive. I actually considered replacing it for last release. It was created based on a specific scenario where it was not used to draw over a person segments but to act as a quick reference diagram on the side. The person would move the segments a bit to make a canonical pose as a note. I don't think this scenario is in use anymore.
3) could it be possibile in the future having a center of mass for the "profile" model too
Yes if we have the coefficients based on the existing segments. Post them and we'll build the tool.
I'm thinking at computing lumbar compression force and moment during deadlift/squat through inverse dynamics and it requires center of mass location as well as trunk angles
I started to update the format for last release, and plan to update it again to make it easier to display computed measures.
My goal would be to be able to display ratios, additions of two segments length, etc. There is a ton of these standard metrics that can be done based on anatomical landmarks and are referenced throughout the literature.
I'm still at the design phase for the framework to make these computations possible. My thinking so far is to add a concept of variables and operators and the tool would declaratively describe a resulting variable by using an algebraic expression tree. This would replace the "computed point" concept and be way more powerful.
There are also several primitives that are missing at the moment, like the possibility to get the angle between two non-intersecting segments, and get the center of a best-fit circle from a few points.
Please send how you perform the measure manually and any bibliographical references we can use. This will greatly help this design phase.
4) would it be even possible in the future to have a tool or add-on (a kind of GUI to friendly create a xml file) to build our own model by specifying body segments to use along with the relevant inertial parameters, joint angles and so on?
It has been a dream of mine but it would be a very big undertaking. For the initial skeleton structure it might be possible to use another application or a Kinovea key frame and convert/import the set of segments into a tool, but that won't help with variables and behavior. So it is going to be a manual process for the time being.