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Calibration Issue
https://forum.ipisoft.com/viewtopic.php?f=6&t=8995		 Page 1 of 1
Author:  Pitr [ Sat Mar 15, 2014 6:00 am ]
Post subject:  Calibration Issue
Hello everybody!

I'm new to iPi software and i'm trying to calibrate a multi-camera scene in Mocap Studio.
I've made a video with iPi Recorder and three Logitec webcams (same model for all webcams).
the problem is that, after adjusting cameras position, when i click the "Calibrate" button, the square that should be drawn on the marker, appears a bit shifted down, so the calibration is incorrect.
There's an attached image that shows the issue.
Hope you guys can help me.

Thanks in advance!

Attachments:
img.jpg
img.jpg [ 142.46 KiB | Viewed 14438 times ]
Author:  vmaslov [ Sat Mar 15, 2014 12:55 pm ]
Post subject:  Re: Calibration Issue
Maybe it's caused by incorrectly defined FOV of the cameras. Image looks a bit stretched in vertical direction.
In the screenshot, I see that you've set to automatically determine the FOV, but this might not work for some reason.
What is your cameras model? What resolution you recorded at?
You may send us your calibration video for in-depth analysis.
Author:  Pitr [ Sun Mar 16, 2014 12:09 pm ]
Post subject:  Re: Calibration Issue
I used 3 Logitech c270 webcams, the resolution is 1280 * 720
You mean the .ipivideo file right? and how am i supposed to send the file to you?
Author:  Pitr [ Sun Mar 16, 2014 12:54 pm ]
Post subject:  Re: Calibration Issue
I've also seen the technical specifications of the webcams and the FOV is 60 degrees
i set the FOV to 60 and i also misured the distances between webcams and the height of each webcam from the floor, then i adjusted cameras position in Mocap, basing on them, but nothing changed
Author:  vmaslov [ Sun Mar 16, 2014 1:05 pm ]
Post subject:  Re: Calibration Issue
I recommend you to use 640x480@30Hz video mode supported by your cameras. Also, our software may not handle properly videos with aspect ratio different from 4:3, because it's uncommon for the cameras mostly used (PS Eye and Kinect-like depth sensors).
Higher resolution does not provide much increase in accuracy with full-body mocap, but produces much more data. Besides, according to the specs, 640x480 mode provides the best frame rate for your camera. And high stable frame rate is of a great importance for optical mocap.
I saw 60 degrees FOV in the specs, too. But I suppose it's suitable only for wide modes (16:9), so you'd better still use automatic detection in our software.

Yes, I mean iPiVideo file. You can zip it and upload to some file-sharing service like Google Drive, Drop Box etc. Or, if you use uTorrent, you can try direct sharing, look here:
http://wiki.ipisoft.com/Huge_Files_Sharing_Using_uTorrent. The measured heights of the cameras are also welcome.
Author:  Pitr [ Tue Mar 18, 2014 5:58 am ]
Post subject:  Re: Calibration Issue
No matter, i already solved it!
i tried to record the video at 640x480@30Hz, as you suggested, and that solved the problem

Thank you very much!!
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