Hi.
I can't rotate camera by horizon in iPi Studio.
I shot video from 3 cameras, and one of those was rotated little right, and horizon was rotated to 5-7 deg. And now I can't fix side rotation (or horizon rotation).

Sorry for my very bad English.

You are not supposed to make such fine camera position adjustments manually.

Did you do the calibration using a glowing marker?
Please see our tutorial video on calibration:

http://www.youtube.com/watch?v=bko8gPKhOaE

Sure, I do the calibration, but one (some times two) camera goes under the ground. At first time i do the calibration, cameras stay normal, but my Windows was crashed, and I not save my scene. Now the cameras go crazy, and only way I can set it is manualy.

OK.

After calibration, do you see a good result for relative camera position? Do the 3D points look green (you need at least 70% of green points)?

If yes, the do you define ground points after calibration? You should not rotate cameras after calibration. You should define ground points and your cameras will be aligned against the ground automatically. You need at least 3 ground points.