blocked marker position data in c3d file


If some markers’ position data was missed, should we fill the data manually or just leave it? If the data is filled manually, the relative position comparing with other markers may not be right, which may results in wrong results or error when study is running. Is it correct? What is the consequence if gaps exist in the c3d markers’ position data?

Thank you very much.


It is right that filling manually a gap can lead to inacurate simulation and errors. I think it all depends of the gap size. If it is very small i think you can fill it with good accuracy by extrapoling the trajectory, but of course when it becomes too wide this approach is not valid anymore.

It is important to get rid of the gaps because the trajectory data still exist but is simply {0,0,0}, and the model is kinematicaly pulled toward the ref frame origin during the gap.

The other solution is to set the weight of the marker driver to 0 during the gap, so the marker has no effect at all during this period. Read the tutorial to see of to do it.

Best regards, Sylvain.