Hello guys,

My first post here :)

We've been trying unsucessfully to calibrate a 6 PS Eye configuration, but we've been stumbling into various issues and we really don't know what's happening because when we tryied the setup with 3 cameras (before we bought the other 3 and the iPiSoft license) everything worked flawlessly.

While calibrating I noticed that the red square that tracks light keeps tracking random dots while there's no light sources on screen, and sometimes when there's a light source it doesn't follow it, also the square keeps blinking red and green.

We tried many light sources, PS Move, Candle because our flashlight wasn't working properly.

After reading a little more we tried another got with at least 3 cameras always showing the light, still didn't work

After calibrating everything we got ALL our cameras in a wrong position (we did a set up for the cameras before shooting and saved the xml), loaded the XML before calibration, after calibration all the camera positions were wrong (including some that were fliped upside down!) And the green dots and red dots were ALL outside the space were they should've been (inside all 6 cameras volume)

Well, we tried shooting many times but every time we got the same problem.

After Calibration with the cameras in the position iPi Soft rearanged:
http://i.imgur.com/dp23Shv.jpg

After Calibration with the position the cameras should've been:
http://i.imgur.com/GhgwQ4J.jpg


Please help us with this issue!


Thanks!

Hi
As I understand, you have the initial approximation of the camera positions done manually. For it to be taken into account, you should uncheck the Auto detect camera postions checkbox. Auto detection works good for 3-4 cameras, but often leads to bad results with more cameras, and needs to be disabled.

Hello

Thanks for the quick answer!

Yeah, we had it turned on for a couple of tests but then I tried turning it off and we kept getting some bugs, I'll try it again just to be on the safe side. I have a question:

Should I always have the lights turned on and then set the camera to darken? And how is the best lighting condition? We were capturing in a very bright room and then as the night approached it starter to get more dark, we tried also dimming the lights from the windows (as they were too strong).

I don't know if lighting is a major player during the calibration phase, could you help me with that?

Thanks!

For calibration, average lighting should be fine. The important thing is that the tracking marker (usually a small Maglite in candle mode) is the brightest point in frame. This is one of the reasons you need to avoid reflective surfaces in the background and floor. Darkening the room should not be necessary unless the brightness of the room affects iPi Mocap Studio's ability to see the marker clearly. Darkening the video within the software to make the tracker marker brighter can certainly help calibration.

For motion capture, you should shoot in a well-lit environment because iPi with PS3 Eye needs to see everything clearly (shape and colors) to make sense of the motion. In general, Mocap Studio is pretty forgiving but you can help improve tracking quality by following a few 'common sense' rules. For example, avoid harsh directional lighting that casts dark shadows on the performer and background--this can confuse volume creation and tracking. If possible, use diffuse light sources, like soft boxes. Shooting outdoors on an overcast day or very early in the morning works too. If the room has several windows, you can use the light from outdoors to diffuse room lighting but you may want to use translucent blinds or curtains to hide reflections on the glass. Also, be sure to wear appropriate clothing--the details are in the Wiki.

G.

_________________
Greenlaw
Artist/Partner - Little Green Dog | My Demo Reels (2013,) (2015,) (2017,) and (2019)

Watch a one minute excerpt on Vimeo now!

Thanks for all this help guys, you are awesome! I have just one more question.

Last time we did tests we recorded using 3 PS Eye, the thing is is that it was very simple for all 3 cameras to be recording the light at the same time, while on the new setup with 6 cameras it's almost impossible to have all 6 cameras recording the light at the same time (be it for body occlusion or our volume space). Our problem with this was that when the light was out of the camera iPi started to record the brightest point of light that was in the scene, and we kept getting red dots while calibrating, instead of the green flow we should've been receiving (and that we got while trying the 3 camera setup).

What's the best way to capture the light? I've read on the wiki that the rule of thumb is to always have 3 cameras getting the light so should I get 1 camera and make sure the light is always appearing there (like a central camera), make sure the same 3 cameras are recording the light ALWAYS or any 3 of the 6 cameras from the setup in a given time is fine?


You guys are very helpfull, thank you all!

I've been able to calibrate with 6 cameras but our cameras are all quite high (5 of them are fixed to the ceiling). This way we can always use the same calibration file. At some point I had tremendous trouble getting a successful calibration with all of the cameras, though. I had an idea which I didn't have to try but maybe it can help somebody else. Since it is easier to calibrate 3-4 cameras, why don't you try that. For example, calibrate cameras #1..#4 first, then cameras #3...#6. Finally combine the results to one calibration file using a text editor. I don't know if the overlap is necessary but at least that way you could be more confident that the idea worked (locations for #3-#4 should be the same in both calibrations).

Note that I have not tried this, and I also have no knowledge about v2. If the calibration file is binary nowadays or something else has changed considerably from v1, this idea cannot work even in theory.

Any 3 cameras. More exactly, you should have enough green points for each combination of 3 of 6 cameras. To ensure good visibility of the marker to as many cameras as possible, take these tips:

• Always hold the marker in the straght arm, away from your body
• When approaching a boundary of the capture area, positon the marker inside the capture area

Nice idea! Though, I'm not sure that coordinate systems for both camera sets will match. But it's worth trying if direct 6 cameras calibration fails anyway.
Sure an intersection is needed between two camera sets to combine them later.
Scene file (the result of the calibration) is still in XML format.

I was wondering, for a future build, if would it make sense to add dual PS3 Eye calibration? What I mean is the user could hold two Maglites wide apart while performing the calibration pattern. This would increase the chances that at least one tracker is visible to the cameras all the time, and averaging the combined tracking data might increase overall accuracy. I realize the tricky part might be in distinguishing each tracker marker but after a short range of movement, identification should become obvious.

Or maybe that's complicating things too much. Just thinking out loud. :)

G.

_________________
Greenlaw
Artist/Partner - Little Green Dog | My Demo Reels (2013,) (2015,) (2017,) and (2019)

Watch a one minute excerpt on Vimeo now!

Hey Guys!

I'm here capturing more stuff with the tips you guys gave me!

This is our setup:

http://360.io/AnqDMb

This is what we're getting as a result on one camera:

http://i.imgur.com/N7XTaOn.jpg

But when we try to view everything, it's all broken:

http://i.imgur.com/A0xGj6I.jpg

It's a circular 6 PS Eye setup with 2 cameras higher (2,25m), it's better then it was but still not enough.

Any tips?

Just as a small idea, I tape my mag light to a pole and then calibrate. That way it keeps my body out of shots at all times.
It has also helped me having a person watch me do the tracking in Ipi, I will generally hit a ground point and ask my assistant if he can see the light in all the cameras. If he says yes, I move on.

Hope this helps

Oli