<r>Dear Daniel,<br/> <br/> VTK has some converters to import different file formats including STL. You'll need to check kitware's site to find how these are packaged or if they're available in a product that you can download and use directly. Here's a faq page from kitware related to the issue:<br/>...

Dear Daniel,

Can you please send me the details of how you reproduced the problem in OpenSim 1.0 with our own model and data files so that I can investigate?

Thanks,
-Ayman

<t>Dear Fabio,<br/> <br/> 1) It is possible to run a forward simulation to predict movement given a set of muscle excitations. In addition to the muscle excitations, you need to specify the initial states of the model, which include not only the joint angles, but also the muscle activations and fibe...

<t>>>I am wondering if I can output the plot to save as a file?<br/> <br/> We understand the value of the feature to save and restore plots as is, and we're working on implementing it. In the meantime users can do the following in OpenSim 1.0:<br/> <br/> - Export the plot to an image (png, postscrip...

The inverse kinematics solution minimizes a weighted sum of squared errors using IPOPT, a non-linear optimizer.

What algorithm is used for solving the inverse kinematics problem in OpenSim?

<t><br/> As of OpenSim 1.0, the only model modifications available from the GUI are changes to muscles.<br/> <br/> The GUI is not yet in place to let you add degrees of freedom (coordinates) and adjust their properties, or the properties of any other model components other than muscles. <br/> <br/> ...

On the weights tab of the IK tool you can disable whatever markers that you do not want to track.

Force data is imported through the motion file input for IK and is carried over to IK output motion for later usage.

Hope that helps,
-Ayman

What changes can be made to OpenSim models in the GUI? Is it possible to build a model from scratch?

As of version 1.0, OpenSim does not read C3D files directly. Users need to preprocess these files to put their data in the file formats that OpenSim supports:

.mot SIMM motion files
.trc Motion capture files