Open model in OpenSim 3.3

[Alexandra Yurova]

Hi,

how one can convert Opensim model from 4.1 or 4.3 version to 3.3?

Thanks,
Alexandra

[Thomas Uchida]

OpenSim doesn't provide this functionality. "OpenSim 4.0 version model files are not compatible with 3.3 or earlier versions. Do not save a 3.3 version model in 4.0 if you want to be able to also use it in 3.3. OpenSim models from versions 2.4 to 3.3 should open without issue in 4.0 (with the potential changes noted below)." (https://simtk-confluence.stanford.edu:8 ... penSim+4.0)

[Rahmatullah Safdar]

Hi Thomas

I hope my inquiry finds you well and in good health.

I have been trying to post a question on the forum and I am unable do so. Every time I click on post, it logs me out.

My simple question was : Is it possible to load files/models of 3.2 version OpenSim in 4.4 version?
Can we go back and forth between these versions of OpenSim with same files/models?

The way we can run file of one version of MATLAB in another, is it possible to do in OpenSim?

I saw that your answer was "No" in 2012, just want to confirm if it is still a " No " in 2023?

I look forward to your kind response.

Best,
Rahmat
PhD Biomedical Engineering
Wichita State University

[Thomas Uchida]

The original question on this thread was

how one can convert Opensim model from 4.1 or 4.3 version to 3.3?

OpenSim is not backwards compatible in general. Models saved in 4.0 or higher cannot be opened in 3.3. To answer your questions:

My simple question was : Is it possible to load files/models of 3.2 version OpenSim in 4.4 version?

Yes, this is possible. Older models can be opened in OpenSim 4.4. However, old models are updated to the latest format when opened; if you save a model in 4.4, you will not be able to open it again in 3.2.

Can we go back and forth between these versions of OpenSim with same files/models?

If you need a model in 3.2, you can open it in 4.4 but do not save it (or save a backup copy for use in 3.2). The functionality of OpenSim 4.4 should be a superset of the functionality of OpenSim 3.2, so you could consider updating your post-processing scripts if that is the reason for using 3.2.