Body segments scaling

Submitted by sinisa_s on Fri, 08/14/2009 - 05:19

LifeMOD

Dear all,

I would like to create a human model (1790mm in height) and with specified lengths of leg’s segments. For this purpose I used GeBOD library and generated body measurement table (model height 1790mm). After that I edited joint center location table. The lengths of the leg’s segment I calculated as:

Length of the lower leg = Right knee – right ankle (in joint center location table)

Length of the upper leg = right hip – right knee (in joint center location table).

So,I inserted following values for ankle hip ankle, knee fields in dialog box: 3.74015, 21.06299

35.62992. I.e. I would like to create a model whose lengths of the lower leg and upper leg segments are 17.3228346in and 14.5669291in.

After I changed joint center locations for legs I created human body and training joints. But, when I measured the distance between hip and knee joint and knee and ankle joint, the distances of leg segments are not as I specified them in the joint center location table. They are actually: 18.38 and 12.4 inches.

Please,

Can you tell me did I misunderstand the length of body segments or something about joint center table? Do you represent segment length as a distance between two belonging joints or something else? How can I create a human model in which the height of the human model and the lengths of the leg’s segments will be set according to my measures?

Best regards,

Sinisa

Hi Sinisa,As you have found,

Submitted by ebrackbill on Fri, 08/14/2009 - 12:32.

Hi Sinisa,

As you have found, the joint center table is not used to exactly size the model. Becuase LifeMOD uses one of three databases to build models (GeBOD in your case, or Natick or PeopleSize), the values from the table, and from the GeBOD parameters,get passed through a statistical model before the human model is ultimately created. So the values that you entered will be changed in the final model built.

If you want to create a model with exact segment lengths to correspond exactly to a set of measurements, you can use the joint move tool. This is accessible on the LifeMOD Display Toolbox; in the "Move Tools" dropdown box, select "Reposition/Align Joints." This way you can tweak the position of the joint centers to modify the model. There is also an additional option available in the most recent LifeMOD release (LifeMOD 2008.01) such that when you use the joint move tool, all distal segments get moved as well. To do this:

1) Bring up the joint move panel, and move your desired joint to its new location.

2) Press F3, or go to View>Command Window. This will bring up the command window. Look for the command that was just executed from the joint move; it should be something like:

LM General Jmove direction='tra_d' joint=.World.Isaac_Left_Knee increment=10

3) This is the command will need modified slightly. So put the joint back (ie. if you just moved it down by 10mm, move it back up) and then in command window enter the same command with "include_distal_parts=yes" appended to it. So for the previous example, you would enter:

LM General Jmove direction='tra_d' joint=.World.Isaac_Left_Knee increment=10 include_distal_parts=yes

4) Now the joint to move to the position you want it in, and the lower leg and foot (or whatever happens to be the distal segments) will move along with it.

Hopefully this answers your question, good luck with your modeling!

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Body segments scaling

Hi Sinisa,As you have found,