Character Jiggle

[aforetaste]

I recorded a session of mocap several months ago with our 8 camera Optitrack system. We got great recordings with very clean data (no foot jitter/shaking and other skeletal wobbles).

Now, three months later, we can't seem to get that sort of clean recordings anymore. The skeletons feet seem to jiggle and often the upper torso and/or upper arms might twitch here and there.
We've shut off the studio's AC unit (for any jitter to the cameras that that might cause). We've used the NaturalPoint training videos to set up the cameras and to learn/integrate good calibration.

What are we missing?

We have an 8 camera set up. 18' x 18' room (with 8 foot ceilings). The cameras are firmly mounted to walls. The bottom cameras are set up to record in a portrait format. We calibrate before every recording, trying to capture the full volume without going outside of it. We get excellent results during calibration (with a few goods now and then).
We're using the latest version of Arena on a Vista machine (dual core).

As an aside: we are getting more "rogue" markers in our captures as well. They seem to float about here and there and come and go as they please. This may or may not be connected to our twitching problem.

Any thoughts or suggestions would be helpful!

[VincentG]

How far below the upper cameras, are the lower cameras located?

Made any changes to the setup, between now, and the previous good results?

How many data points, are you using, when running the calibration?

Can you send to support, copies of your calibration file, wanding pt2 file, skeleton, and data pt2 files capture (t-pose)

[aforetaste]

Thanks Vincent for the help!

The lower cameras are 29" lower than the upper cameras.

We hadn't changed any part of the setup since the good recordings. Since then, having had some poor recordings we turned the lower cameras to the portrait setting... with no luck.

Data points when calibrating? We're using the default 100

I'll be glad to email all the files I can to help.
Thanks again!

[aforetaste]

Hmmm... I'm not finding an email address where I can attach the requested files.
On the support page it doesn't appear to allow any attachments when contacting support.
How shall I go about this, Vincent?

[VincentG]

NaturalPoint Technical Support
Support at NaturalPoint.com

[aforetaste]

As for one thing that DID change, I just remembered,... we did reinstall our copy of Vista on the machine that runs Arena.

[aforetaste]

Okay, I've had a modicum of success!
I used to have no idea that the T-square floor calibration set the Z axis. I'd set it any old way on the floor.

Then, once i did figure that out, I started to have it point toward one of the sets of cameras. If I do this, and stand perfectly still (in a T-stance) I see no problems. But when I move just a little bit, the different body parts (for me it was especially the upper body) start to jiggle.

When I recalibrate back to a blank wall (between two sets of cameras) I don't get the jitter when I do small movement.

To Recap: when calibrating the cameras (specifially the floor/ground plane) make sure to position the T-square (the Z axis) between cameras rather than directly towards them. Worked for us a bit!

[kitesflyer]

I have a 6 camera setup from optitrack,after an excellent calibration (for all 6 cams)I am getting a fairly jittery data,can anybody suggest any way to get rid of this jitter as it is making my work flow really slow.Is there any filter available inside of Arena that can reduce this or do I need to avail of the filters available in Motion builder,if yes then which one?.I need to reach a solution really quick as it is posing a great problem to my pipeline.

[DonBurroni]

try changing the camera processing mode, to Precision Greyscale
hope that helps,

maybe your cameras are too low also, it sounds like you are reaching the volume limits.

[Seth Steiling]

Hi kitesflyer001,

Please don't duplicate your posts across the forums. We read all new forum posts, so this is not necessary to get our attention.

Can you describe your setup? Dimensions of the camera setup area (including height), size of the capture volume you've aimed for, orientation of the cameras (portrait vs. landscape--and keep in mind, when the camera case is portrait, the imager is actually landscape) what you're capturing, etc.

What lenses are you using?

Also, perhaps most important, under the Point Cloud tab on the right side of ARENA, make sure "Min Line" is set to 2, not 3. This is very important, for 6, 8, and often 12 camera setups.