Shoulders problem

[Admir]

Hi,
i have setup mixed system with 6 V100r1 and 8 V100r2 cameras running Arena 1.7.

Calibration went fine (using both 3 marker wand and 1 marker wand).
I have problem with skeleton. Recording of T pose went ok, height and shoulder distance is entered correct.
No matter what marker setup we have we are getting either clavicle bones stretching (i can disable adjust bone length) or bones of upper arm and clavicle detached from joint. It happens when motion is "hug" like or arms are pointing down (relax, idle pose). When reviewing recorded data, markers are in correct position but markers from skeleton cant reach them. I ll attach example images.

Thnx in advance,

Admir

[NaturalPoint - Mike]

Could you send pictures of your actor, markered, front and back to support@naturalpoint.com? I'd be willing to guess it is likely a marker placement issue.

[Admir]

Hi Mike,
sent email with photos,
Thnx for looking into it,
Admir

[NaturalPoint - Mike]

It appears you're using the 38 marker setup. If that's the case, the issue is with the top upper-arm markers. They appear to be on the shoulder enough that it is compressed towards the other upper arm markers when you raise your arms. Try lowering the upper arm markers and making them more of a triangle, as in this picture:


When measuring shoulders, the measurement should be made not from outside to outside, but from pivot point to pivot point. Put your fingers on top of the shoulder and have the arm move up and down until you find the point where you can start to feel the movement of the arm, just inside of there is where you want to measure.

[Admir]

Hi Mike, sorry i forgot to mention it, it is 38 markers setup.

How important is calibration quality for skeleton wizard ? I am getting excellent result but needed to change min/max line settings to remove ghost markers.

Thnx for help and your time,

Admir

[NaturalPoint - Mike]

It's important for any time you're tracking markers, including skeleton definition.

Min lines up is a good way to combat extra markers, however with less than 12 cameras it should be 2. Lowering the residual works, as well, even on smaller set ups, however this is highly dependent on a solid calibration to function properly without removing legitimate markers.

[Admir]

Hi Mike,
i have managed to get couple days of very good sessions. Played alot with shoulder markers positions and got new actor to fill suit more to avoid sliding.
Today i have noticed that i needed to raise residual to around ~20 to remove ghost markers appearing. Cameras havent been recalibrated from saturday, but they are immobile, on trusses and stands that noone touches or moves. Only diff was that i have recorder new skeleton today.

Anyway, all is good, will do more capturing this week and then Expression time

Thnx for your help and support,

Admir

[NaturalPoint - Mike]

Your residual is around 20? That's really, really high. I generally try to get as low as I can without loosing too many markers, and can generally get 3 to 5 for a good size volume, and as low as 1 or 2 with an expression volume. You may want to try recalibrating to ensure some cameras didn't get nudged or settle as they warm up and cool down.

[Admir]

Camera temperature could be issue, tho room has aircondition system.
Will see today how it behaves.

Admir