Calibration >2 depth sensors with board
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Author:  Manoroc [ Mon Apr 18, 2016 11:40 am ]
Post subject:  Calibration >2 depth sensors with board


I have 3 KinectV1. Calibration 2 KinectV1 with board works great, perfect quality, but for 3 KinectV1 it is unavailable (only calibration with light marker). Calibration 3 KinectV1 with Maglite's flashlight (or PS Move) - the quality is very bad, I have 5-6 times to redo the calibration for medium-good quality.

Do you plan function of calibration >2 depth sensors with board?

Or can three sensors calibrated in pairs with board, and then somehow merge the data in a scene file with 3 sensors? As I understand it, in the XML scene file I can change parameters of each sensor manually.

Thank you in advance for answers.

Author:  vmaslov [ Tue Apr 19, 2016 2:42 am ]
Post subject:  Re: Calibration >2 depth sensors with board


We do not plan to extend board method for larger numbers of depth sensors. Actually, in our tests flashlight method has better accuracy when done properly.

Maybe you have problems with light marker detection in your videos due to bright lighting or occlusion. If you share some of your bad calibration videos, I could probably provide you specific recommendations on improving the calibration technique.

Author:  Manoroc [ Tue Apr 19, 2016 8:19 am ]
Post subject:  Re: Calibration >2 depth sensors with board

Hello, vmaslov.

Thank you for answer!

I think that the main problem is that I can't change settings on my Kinect (in the "Properties" tab). I can't turn off the "Auto White Balance" (which spoils the video quality), because all the buttons do not work (except "Elevation angle"). I don't know why. I just press a button, but it don't seem pressed. I have this problem in iPi Recorder 2 and iPi Recorder 3. Reinstalling drivers for Kinect did not change anything.

Can you please have any advice?

Author:  vmaslov [ Tue Apr 19, 2016 9:52 am ]
Post subject:  Re: Calibration >2 depth sensors with board

If you've got Kinect for XBOX 360 - it does not allow to set any props besides elevation angle. Only Kinect for Windows does.
Do you have any errors in iPi Recorder log after trying to change values of Kinect props? To view the log press button at the top-right of the program window.
Could you provide screenshots with Properties panel and calibration problems?
To improve marker recognition, try to dim lighting during recording and choose different settings for marker size before running calibration in Mocap Studio.

Author:  Manoroc [ Tue Apr 19, 2016 10:55 am ]
Post subject:  Re: Calibration >2 depth sensors with board

I have "Kinect for XBOX 360", but in iPi Recorder it displayed as "Kinect for Windows" (other Kinects displayed as "Kinect for XBOX"), and it have "Properties" like that:

In log it says "Can't get value of property 'Auto White Balance'... The feature is not supported by this version of the hardware". But I think "Auto White Balance" is yet work, because...

Light problems are simple - in completely dark room this Kinect see nothing (even marker), but other Kinects see marker. In not completely dark room this Kinect see light room, but other Kinects see dark room. So I need to record calibration in a bright room, but it spoils the quality of calibration. Also, when I put on camera sunglasses (just for test) - video first become dark and then become bright again.

Unfortunately, I deleted the videos, but this Kinect exactly have the problem with the automatic white balance (especially in dark room). Do you think that the problem might be in the device?

Author:  vmaslov [ Wed Apr 20, 2016 12:52 am ]
Post subject:  Re: Calibration >2 depth sensors with board

Definitely there is something with this specific device. We distinguish between Windows and XBOX devices by their vendor and product IDs reported to the OS.
For some reason, this sensor reports the same VID&PID as Kinect for Windows. Maybe, it has updated firmware version, which does not support controlling color camera settings though.

I think adjusting picture according to environment lighting has more connection with Auto Gain setting rather than with Auto White Balance. Anyway, you have no control on this :(

Author:  Manoroc [ Wed Apr 20, 2016 4:12 am ]
Post subject:  Re: Calibration >2 depth sensors with board

Well, I will try to do anything with the firmware (or something like that). On the other hand, 25-30$ for a "new" Kinect - not too expensive for me, and medium quality calibration - also gives the normal quality for some movements.

Thank you very much for the advice! ;)

Author:  Greenlaw [ Wed Apr 20, 2016 2:28 pm ]
Post subject:  Re: Calibration >2 depth sensors with board

I'm usually working with two sensors but when I use three sensors, I've run into some problems with using the light method too. In my case, it has entirely to do with the brightness of the room during daylight hours. In fact, I even have problems with board calibration during the day if I don't cover some of the windows in the room. (It's been less of an issue with Kinect One though.)

What I usually do is record in the evening when I have better control over room lighting. Turning off all lights except for one overhead seems to work best, and I've even considered putting that light on a dimmer for recording calibration video.

I don't know if that will help you but you might give it a try.


Author:  Manoroc [ Wed Apr 20, 2016 10:30 pm ]
Post subject:  Re: Calibration >2 depth sensors with board

Thanks, Greenlaw, for the advice!

These methods gave me at least some result before. However, I have replaced the problematic sensor on the other (exchanged with my neighbor), and the problems become much less. ;) Still, it was more a technical problem with only that Kinect than with software.

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