validity using different softwares

[Kate Tong]

Does anyone know if I am doing 2 parts of motion capture experiments with same set up but different conditions, is it valid to compare their angular results if I am using different motion capture software? (The 3D data will all be exported to Visual3D for analysis in both cases. But one will be using the motion capture software to edit first before going to Visual3D, the other go straight to Visual3D for editing and analysis.)

[Josh Baxter]

Re: validity using different softwares

You are probably OK but why does one software package post process data and the other does not? Are these experiments performed sequentially so that markers stay on the subject or are markers removed? All motion capture systems have measurement resolutions that far surpass the amount of skin and other experimental artifacts. It would be helpful to know what you are asking and what you are trying to measure during what type of activities. Different marker sets are appropriate for different questions.

[Kate Tong]

Re: validity using different softwares

Thank you very much for your reply. The first software we used was a simpler program, so do not have editing functions. They changes 2D data to 3D data and you can identify the markers, that's pretty much it. But the other software has all the general functions of editing each individual trial on selected time frames, etc., and are visually more user friendly. But I am fine now, thank you!

[Edmund Cramp]

Re: validity using different softwares

I agree that you are probably OK - it's unlikely that an editing application would change the data in this way without alerting you to the modification. However it would be quite simple to perform a simple test with three of four targets in known locations and check that the locations do not change after processing with each method.

[Kate Tong]

Re: validity using different softwares

Thanks for consolidating the idea and your suggestion for testing. I think the new software has better editing feature and allow interpolation of time frame of a particular marker. Also the ability to delete a nonsense point and link it up better, etc, are all good features. Just the way how things can be edited I guess would result in better and more accurate guess of data where data are missing. Thus that's why I think the result can be slightly different though it can only be better. Thank you.