one camera losing calibration

[jgomezb52]

Hi,
I've been suffering a special problem. We are using an Optitrack system with 6 cameras VR100:R2 with wide lens, 2 USB Opti-Hubs (3 cameras per hub), and 2 and 1 active USB extensions per hub. The software is Tracking Tools 2.3.0. The problem is that after calibrating the system, I test that all cameras detect properly one reflector. Just after the calibration, all cameras are tracking the reflector properly, with the yellow cross on the center of the "white" ball. But one of the cameras (number 4 that is also the last in the hub order) has the yellow cross a little bit displaced from the center. This situation remains steady after changing the position of the reflector in the room. At the next day and without any modification (except to turn on the computer) all cameras detect the reflector correctly except camera number 4 that do not detect the right position of the reflector even when the reflector is shown on the camera screen. Instead on the yellow cross there is a yellow rhombus displaced from the reflector. I could think that the camera has move (because gravity) but the displacement indicates that the camera should be rised up to give that position so I think it lose the calibration somehow.
Can somebody help me with that?

[NaturalPoint - Mike]

Hello -

Calibration data is not stored on the camera, so it's not an issue of a camera "losing calibration" so to speak. Movement does seem to be the most likely option here. Have you tried recalibrating the system?

[jgomezb52]

Every morning during the last two weeks that camera (or the software that process the images of that camera) do not recognize any point as part of the rigid body, so I calibrated the system again every time. This last time it seems to be almost right (still is not on the center of the reflector but close to it). Anyway, I'll test it again in one week and then I could say if it is working OK or not. On the other hand, the big problem now is that after a while Tracking Tools software stops to handle one of the two hubs we have. Do you know why it can be? If I turn off the program and restart it again then it works, but that is something I cannot do during my measurements (since we use that data for tracking the position of one loudspeaker respect the listener).

[DonBurroni]

I think the sync between the hubs is not working, u may have a faulty hub,

try unplug and re-sync the hubs, do you get a lot of software crashes?

[DonBurroni]

ps try with just ONE hub and see if it is more stable

[jgomezb52]

With only one hub will be impossible just because where the cameras are (too much distance between). I'll check the sync, maybe the wire has some problem. Thanks for the idea. On the other hand I could change the hub since we have another system around.
And yes, the software crashes very often. I've just updated the software Tracking Tools for version 2.3.3 let see then.

[NaturalPoint - Mike]

When tracking tools stops recognizing a hub, does the hub itself disappear from the asset manager or do the cameras plugged into the hub re-number themselves?

[jgomezb52]

When I start Tracking Tools everything seems to work fine. After a long while (around an hour or two), one of the hubs (always the same hub) seems to be lost since the cameras connected to it appears at the center of the perspective view (like before doing the ground plane setup) but keeping their numbering. In the project Explorer in the Devices section the hub disappears. Furthermore, sometimes it just does not appear when starting Tracking Tools so I need to restart the software. In other cases, the hubs are in the Devices section but in the camera preview it read Sync:Software in red when usually is Sync:Hardware (in white). I changed the USB connections so the hubs were at different USB controllers but nothing change.
Actually, the hub that disappears is the hub that give the sync signal to the other. I also release a little the sync wire since it was too tightened (this and the update has improved the first problem but not the second one).

[NaturalPoint - Mike]

If you switch the two hubs so that the one with the issue is second and the one without the issue is first, does it still exhibit the issue?

[jgomezb52]

I switched the hubs and it seems to be better, at least it keeps working for longer time (but sometimes the software does not recognize both hubs but the cameras are there). However, if I connect whatever device to the electrical network, the Tracking Tools loses the cameras (all of them shift to the origin)so I think that the hubs have some problems with that. Probably a power stabilizer could fix that. On the other hand, I realized that the first problem, that the tracking does not recognize the reflector in the image as part of the rigid body, still appears after some time when the computer is restarted but I just fix it calibrating every time the system if I detect this issue.