simtk.org

Hello,

I have been using the dolly camera tool in OpenSim 3.3 to create some movies of my model motions; I really like this feature!

So far I have been manually orienting my camera at a given time interval to how I want it to be, and saving that configuration to the list in the Camera Editor window. I can then save the resulting 'camera motion' as a .cam dolly settings file for later use. However, I'd really like to be able to programmatically set up a sequence of camera configurations over time, so that the resulting 'camera motion' is smooth and precise. I was thinking of writing some MATLAB code to print a .cam file for me that will do this.

The problem is that I do not understand what all the individual entries in the .cam file (or in the GUI window, see attached screenshot) actually means, preventing me from writing a .cam file without needing to consult the GUI as to what the entries do. (Some are easy, like 'pos' and 'dir', but others I haven't a clue.) I haven't been unable to find any documentation outlining this, so was wondering if anybody may be able to provide some insight here please?

Many thanks in advance for any help, and stay well all!

Peter Bishop.

Hi Peter,

The attributes of the camera (e.g. Clipping planes near/far, focal point, up direction etc.) are built into the camera object from vtk (the visualization package we used then). The GUI performs interpolation of these camera positions to generate the movie. You may want to lookup the info for vtkCamera online for explanation.

In version 4.0 we moved away from vtk to a new visualizer, so you may want to keep that in mind before investing time in writing your own camera interpolation code.

Hope this helps,
-Ayman

Hello Ayman,

that's perfect, thanks! Searching for 'vtkCamera' online produced all the explanation I required.

If anybody else runs into this, this website is very handy: https://vtk.org/doc/nightly/html/classvtkCamera.html

Thanks again,
Peter.

Is it possible to set a specific camera perspective (as described above) in OpenSim 4.1 without having to manually rotate the screen in the GUI?

Thanks for your help!

Ty