Is the IMU calibration tool still working (has it ever worked for this?) and given out by support? Otherwise, what's the current way for (trying to) solve this? Is an Oculus repair install also (trying to) re-calibrate like a complete de-install and new install of Oculus does? Is a "full setup" from within Oculus trying to recalibrate as well?
Is this a software/timing issue or are there units which are more affected by left tilt than others? Is there any metric in log files that could give an indication about how severe the tilt is?
Is there really no, even if "secret" way to add an offset somewhere to compensate for a few degrees of tilt?
I just run the IMU calibration tool and it IS level now. (I actually didn't expect this, but it did work.)
What I did, according to instructions, when I got up today my Rift was "cold", so I thought why not. Removed facial intf (because stupid vrcover triggers the sensor) Put Rift upside down in a box with a towel underneath, locked out my effing cats. Used a level and made sure Rift is level horiz/vert. Ran the tool. (Took 10 mins).
For verification I am using "Deskscene" (the horizon), and check horizon position using a simple meter on my monitor, with the Rift level. And usual visual inspection, Oculus Home etc. Before, I absolute had a noticeable tilt which I could measure using DeskScene and seeing the hoizon slant.
So the IMU calibration tool works, at least for me. If you have a tilt, contact Oculus since the tool cannot be shared. (I had some people claiming this tool isn't working anymore or not given out anymore, but I mean it solved my tilt, that's all I can say)
** How you use the tool: Your Rift must be cool, room temp, so unplug it for several hours, best over night. Remove facial intf, put Rift upside down. Not sure whether level is necessary, but possibly so. Level out the Rift. Replug Rift, run the tool. There cannot be the slightest movement, vibration or anything during the 10 minutes the tool is running. When the tool has finished, the calibrated settings are saved into the Rift and should persist.
No, it hasn't (IMHO) anything to do with the cameras. It also SHOULD not matter how you put on the HMD. I mean, the Rift has internal sensors, it should know whether it is level or not no matter what. (My cameras/sensors are in the same position ever since I have the Rift, one sensor is always higher up than the other). Since I think my latest Rift had the most-pronounced tilt, I don't think it has anything to do with sensors or anything else really. (Then again, I never measured the tilt in the previous units. It could well be they also had a slight tilt. Sometimes this is very subtle.)