Markers' mean error diverges

[orita]

Hello all,

I use OptiTrack FLEX 13 cameras and rigid bodies with 4 reflective markers on each one of the bodies.
I saw that the markers' mean error starts at 0.01 mm/marker and goes up and up as time goes by (attached 'capture1')
even when (I think) I well spreaded the markers (attached 'capture2')
It causes bad path tracking control.

how to solve that?
Is there a recommendation for minimal distance between the markers? and is it possible to use only 3 markers for each rigid body?


Thank you very much
Orit

[steven.andrews]

Hello Orit,

Thank you for reaching out to the community regarding your rigid body tracking.
If the mean marker error is slowly increasing, this could be due to loss in your overall system calibration. This would cause noisier marker data, which would likely cause an increase in the mean marker error.

You can view the system's residual in the Status Panel. If this is low right after calibration, and then higher later on, this means the calibration is degrading. This is usually due to environmental factors, such as temperature fluctuation or vibrations on the camera mounts.

You can use three markers for a rigid body, but this does not leave any redundancy and the rigid body can stop tracking if a single marker is occluded. Using 4 markers versus 3 should not cause the marker error to get worse with time.

If you continue to struggle with this, feel free to reach out to our Support team directly.

Best regards,
Steven
--
Steven Andrews
OptiTrack | Senior Customer Support Engineer
help.naturalpoint.com
support@optitrack.com

[orita]

Hello Steven,

Thank you very much for the reply.

I use 1.7.5 Motive and I can't find the control panel.
When I click the bottom right corner, a control log pops up (attached)
I dont have the Residual there.

Will appriciate your help
Orit

[steven.andrews]

Thanks Orita,

Motive 1.7.5 is quite old, and not something that was well documented. The status panel does not exist in that version, but I believe the residual may display somewhere at the bottom of Motive. If not, I am not sure where to find the information we are looking for.

Best,
Steven
--
Steven Andrews
OptiTrack | Senior Customer Support Engineer
help.naturalpoint.com
support@optitrack.com

[orita]

thanks for the response.

another question,
what is the best markers configuration?
how do I know the markers were well spreaded?
do I want maximum overlap or not overlap at all? I attached a few examples


Thank you in advance
Orit