scaling

[xueqin luo]

hello everyone
I want to know if there must be a device like VICON for scaling?If my lab doesn't have such a device,only the 3D gait meter,can I use a generic model to build a personalized model,what should I do?
I will be grateful if you can answer my question.

[Dimitar Stanev]

The marker trajectories are used to extract the scaling factors applied to the generic model. If you don't have this information you can measure the segment lengths and perform manual linear scaling.

[xueqin luo]

Dear Dimitar Staney
Thank you very much for your answer.I am a student who just contacted Opensim.My tutor wants me to use this software to simulate the effect of surgery,but there is no VICON device in my lab.I have learned that there are two ways to scale,one is based on measurement scaling,another is based on manual scaling.I saw this on the official website about manual scaling,as follows:
A scale factor of 1.0 means that no scaling occurs.In the above,all of the scales representing uniform scaling(equal x,y,and z scale factors).
Note:the scale factors below were computed using a utility that computed experimental segment Lengths using a functional joint center approach.This utility is not yet part of the standard OpenSim distribution.
So I don't know how to calculate the scale factor.If you know there are other ways,can you help me?Thank you again for your reply.I am looking forward to your reply.
With best wishes.

[Brody Hicks]

So, is there a way to figure out what the original segment lengths are for a generic model so I can figure out my manual scale factors if I am going to be measuring segment lengths manually instead of having Vicon do it for me? Does the generic model .osim file explicitly state each segment's length? Thank you!
William

[Thomas Uchida]

So, is there a way to figure out what the original segment lengths are for a generic model

I provided a couple ideas in my second post to Topic 9378: viewtopicPhpbb.php?f=91&t=9378.