modification of surface geometry of femur and pelvis


Perhaps I need to elaborate my question again as there is no reply to the last question.

I want to change the bone geometry of the pelvis and the femoral head based on the deformation of FE model, and run modified model in AnyBody.

So, the shape of bone need to be modified in AnyBody. Here I post my last quesetion that nobody answered:

"I want to change the geometry of femur and pelvis bones in two ways:

  1. change the geometry of the femur head and the acetabulum
  2. cut off the femur head and tie a segment on the notch

All these modification should be conducted in GaitLowerExtremity and GaitFullBody model (AMMRV1.2).
I guess the .anysurf file contains these geometry information but not quite sure.
Could anyone tell me how to realize the modification?"

Please, any suggestions will be appreciated.

Thanks a lot.


Hi Jerry,

You can modifiy the bone geometry in two ways. If you already have a new CAD file in stl format you can simply include intead of the existing one (copy your file in the desired body part folder and change the name if needed in the code).
You can also export the AnySurf files as stl and modify them with the CAD editing software of your choice. Then feed them back into the model.

This is done in the body parts and therefore affects all the applications using those body parts.

More importantly you have to remenber that the bone geometry is only for visual purpose. Changing the CAD files will not change the mechanic of the model. To do so you will have to modify the joint, segment or nodes definition in the script.

Best regards, sylvain.

Hi, sylvain

Thanks a lot for your kindly reply.
I know that changing the stl file will not change the mechanics behaviour of the model. But if I change the joint surface geometry and define the joint as a contact model, I guess that will affect the mechanics behaviour of the model. (how to define a contact joint is also a problem)

BTW, I did not find a stl file for the lower extremity model. Only .anysurf file. Could you please tell me the differences between these two files?

If the GaitLowerExtremity model (AMMRV1.2) do use stl file, which part of the code include stl file.

Thank you.


Hi Jerry,

The contact can be defined using for example the AnyKinPointSurface object which allows you to do have contact between a point cloud and a parametric surface. Please look up the details in the reference manual, please note that in the bottom of the reference page for the object you can find sample files showing how to use the object.

The difference between and AnySurf file and an stl file is that the anysurf files may have different normals in each corner in contrast to the stl files which use the same normal for the entire triangle.

Please have a look in the the Seg.any files this is where these files are included into the models.

Best regards