Is your Rift's view tilted / slanted? Here's how you fix it — Oculus
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Is your Rift's view tilted / slanted? Here's how you fix it

ArticateArticate Posts: 7
NerveGear
I am writing this thread in response to my experience with Oculus support. Oculus support has an extremely quick first line support, however they did not have the tools to deal with this issue, and the second tier seem to go through this dance of "please provide pictures of the issue", which seems like a waste of time. I am writing this thread both to let Oculus know their routines on this issue should be improved, and to help those who anxiously await the support they want.

Fear not! Most of the time, the Rift isn't faulty!

There is a calibration tool for the IMU (Inertia Measuring Unit - it's the part that measures how the Rift is rotated, tilted etc) that I used with great success. I want to link to the guide I used, and point out some important parts about this:

1) YOU'RE DOING THIS AT YOUR OWN RISK
This is important. It seems like Oculus do want some sort of control of who uses the tool since it's not that easy to get. It would be pretty easy for the Oculus team to pack this into a nice GUI with steps of how to perform a recalibration, so since they haven't done that, it could indicate that in some cases, this might not be the right thing to do. Without the support team saying "yes, you can run this tool", you should not assume that this will fix your problem, nor be certain that this won't make things worse. At worst, it can be harmful to use this tool, so be cautious when using it, and do this at your own risk

2) This is specifically for issues where the horizon line is slanted or tilted. I think the best way to notice this is just to put on the HMD, pull up a grid view (like the universal menu). If you notice it here, it most likely is there. This rules out the surface you put it down on being slanted in itself, etc. This is never due to a slanted sensor, as the sensor knows what is up and down.

It is very important that the calibration is run when the Rift has been completely disconnected for hours and hours. Leave it alone overnight. This is because the tool calibrates the IMU at all temperatures, since temperature affects the IMU. It runs for ten minutes so it can go from cold to hot and calibrate all the steps along the way. It is also important that it is placed on the most stable surface you can find.

Follow all the steps and use this guide, you can download the tool there:
http://www.vrheads.com/how-fix-oculus-rift-calibrations-problems

This fixed my problem. I hope this can help others. Remember that this might be the right cause of action. Contact Oculus support if you are experiencing this issue, perhaps even say that you do intend to use the calibration tool, and ask if it's the right thing to do. I hope this post can make Oculus' response to this issue be more efficient, as it is such a well-known issue that there should be a standardized response.
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Comments

  • gamefan101gamefan101 Posts: 194
    Art3mis
    It would be soooo much simpler if we could just have an offset value in the config file that we could tweak with no "DO THIS AT YOUR OWN RISK" warnings, rather than risking a bricked rift!!
  • flexy123flexy123 Posts: 791
    3Jane
    edited March 2017
    Thanks for this (interesting) tip but from reading this I wouldn't want to touch this tool with a stick.
    Didn't need calibration EVER until after 1.12. The problem can not be wrong calibration, why would it all-of-a-sudden become uncalibrated, randomly at odd times. So the actual problem must be something else. AND OF COURSE it is software, not a hardware issue.
  • Scope666Scope666 Posts: 14
    NerveGear
    I have the tilted horizon issue with 1.12, and re-calibrating the IMU does not help it at all.  From my understanding the IMU is more about acceleration and tracking movements and not so much determining what level is.
  • GATOxVoSGATOxVoS Posts: 440
    Trinity
    Can any oculus dev or someone with the software knowledge just tell us what determines floor level? It'd be so much easier to fix this issue if we knew what the software was using to determine this. Same with floor height. It's not like another company is itching to get their hands on that info, especially since everyone is moving towards using the lighthouses as their tracking method of choice.

    I too have a slight tilt in floor level, but mine is tilted forward, so it feels like I'm standing on a very slight downward slope. I've noticed after moving my sensors around to different places, the slope will change directions and/or gradients (gradient, grade? I forgot xD).

    If we knew this info, I bet it would also save Oculus support a lot of trouble.
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  • cyberealitycybereality Posts: 26,156 Oculus Staff
    The floor height position is set when you calibrate the headset during the setup. It asks how tall you are, then it has you stand in place and press a button. The camera can see how high your head is, and it knows the height you entered, so it can figure out at what height the floor is at (by simply subtracting your inputted height from the visible position seen by the sensors). Also, with this same information, it can tell the position of each sensor. 

    The levelness of the floor is a little more complex. This is determined primarily by the gravity vectors from the accelerometers as well as combining information from other sensor values. An un-level floor could mean that the IMU was calibrated poorly for your location (things like room temperature can adversely affect the readings) or it could be some issue with the IMU hardware itself. There could also be a software component to it. I've heard of people reinstalling the software and it resolving the issue, but I have not seen what the actual issue is specifically.
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  • GATOxVoSGATOxVoS Posts: 440
    Trinity
    edited March 2017
    @cybereality Thank you for your reply.

    I kind-of assumed the height was determined that way, but I had hoped that there were other factors that checked the positioning to give a better, more solid value for height. I fear that only using the HMD position during setup is not a steady enough constant for something such as height (such as, what if your HMD is slightly tilted when running the height setup, does this give different values for floor height than if the HMD were completely level, even if in the exact same vertical and horizontal positioning in the playspace? I can't imagine that everyone when wearing the HMD has it impeccably level each time, or maybe I'm just a clutz? lol. Also, if tilted just slightly during setup, does this then change the way the software recalculates height during gameplay, causing perhaps more jumps than if the HMD were completely level during setup?)

    As for floor-levelness, could you speak on what sensor values are being used? It is interesting to note that for my setup, as I walk around my playspace in Oculus Home, the floor levelness "can" change depending on what direction I look (not immediate, have to stare in a direction for a few seconds and then a recalc can happen) and if sensors are being occluded. ("Can" because sometimes this change is hard to replicate). Sensor placement has indeed had an effect on floor levelness in the past, at least for me.

    Random P.S. If there was any way to utilize the Rockband VR controller attachment during the sensor setup to correctly determine floor height (place it in middle of playspace, place it in 4 different positions on the floor, whatever it takes), that would be amazing. I would think having a LED or controller actually on the floor would be a much more effective way to setup floor height/floor levelness. Please correct me if I'm wrong though
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  • cyberealitycybereality Posts: 26,156 Oculus Staff
    edited March 2017
    I was kind of oversimplifying things and I did not work on the code myself. What I said is a general idea, but there is a lot of complex math that goes into it I probably don't understand. For example, having the headset slightly tilted during setup should not be any problem (it's smart enough to know the orientation of the device and account for that). 
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  • Scope666Scope666 Posts: 14
    NerveGear
    @cybereality  An interesting thing I've noticed, the IPD adjustment screen with the "+" is perfectly level... I came up with this test where you get that "+" to look perfectly level, then quickly hit the back button and use the top of the Robo Ready ad in Oculus Home as a horizon, it's definitely off by a few degrees.  (left side is lower than the right)

    This makes me think it's a software issue and not the HMD itself   (since the "+" is perfectly level, and I would imagine that screen is not using the cameras)





  • cyberealitycybereality Posts: 26,156 Oculus Staff
    Yeah, anything is possible. At this point the best thing would be to create a support ticket. This will help us track the reports coming in better, and maybe see a connection if we can get multiple people with the same issue. 
    https://support.oculus.com/
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  • Scope666Scope666 Posts: 14
    NerveGear
    Yeah, anything is possible. At this point the best thing would be to create a support ticket. This will help us track the reports coming in better, and maybe see a connection if we can get multiple people with the same issue. 
    https://support.oculus.com/

    I opened a support ticket when I first noticed the issue (the day the Rift arrived, ticket number 338629)

    I've commented in this thread and the others to try and get a sense of how many others have this problem, and give it some additional visibility.     
  • flexy123flexy123 Posts: 791
    3Jane
    edited March 2017
    I just had it bad while checking out the (otherwise fantastic!) "Mission ISS".
    I just came up with an interesting thought:

    Do people who experience the slanted floor have a non-symmetric sensor setup, with one sensor possible higher than the other? And how many sensors do you have?

    My setup is two sensors with one sensor approx 0.5-0.6ft higher up than the other. Just a shot in the dark here, but maybe there is a connection. (Darn I am dizzy now after this and the slanted floor didn't help with that either...)

    I am trying to reproduce this, maybe the ISS experience is a good way to do it.
  • kojackkojack Posts: 5,245 Volunteer Moderator
    edited March 2017
    There's only two ways in current VR to determine floor position: steam has you put the hmd on the floor, oculus has you enter a player height then stand still while the sensors do that animated sweep thingy. The steam way is probably less error prone, but oculus sensors have only 70 degrees verticle fov compared to lighthouse 120 degrees, so seeing the floor as well as reaching up like in The Climb is less likely.

    Scope666 said:
    I have the tilted horizon issue with 1.12, and re-calibrating the IMU does not help it at all.  From my understanding the IMU is more about acceleration and tracking movements and not so much determining what level is.
    An IMU has three parts: accelerometer, gyroscope and magnetometer. (and temperature sensor, so really 4).
    The accelerometer tracks acceleration. This could be due to movement (moving the controller from one place to another involves accelerating and decelerating). But gravity is also a constant acceleration of 1G (actually varies around the world due to the composition and thickness of the earth below you). When the hmd is left on a stable surface, it doesn't read 0 acceleration. It will read 1G in some direction. The direction of acceleration is used to determine the level direction.

    The gyroscope measures angular acceleration, which is acceleration and deceleration of turning. But it has no reference point, it doesn't understand how the hmd is facing in world space. It only understands changes in facing. You still need the accelerometer to determine gravity direction.

    But gravity can only tell you pitch (looking up and down) and roll (tilting side to side). You can't tell yaw (turning around while looking level) from an accelerometer. If you know the initial direction (like the direction you face when starting a game), then the gyroscope can track changes from that. But these values will drift over time (so your front will slowly become wrong).

    The magnetometer tries to correct that. It measures magnetic fields and used those to determine which way you are facing. A bit like a compass. It's not accurate enough to use for much, but it can help counteract drift.

    The IMU is read hundreds of times per second, far more often than the frame rate of the rift. This lets us do things like timewarp, which uses multiple IMU reads per frame.


    That's the hmd (and how the DK1 worked). Now for sensors (DK2 and CV1).
    The sensors are webcams. They look at the pattern of IR lights on the HMD and calculate where the HMD is relative to the camera, and which way it's facing (also relative to the camera). The sensors have no ability to track their own position or tilt. Instead they look at the HMD and compare how they think the HMD is tilted to how the HMD's accelerometer says it's really tilted:
    sensor: "I see the HMD is tilted 20 degrees to the left"
    hmd: "I'm tilted 5 degrees to the left"
    sensor: "oh, that means I must be tilted 15 degrees to the right!"


    Then sensor fusion happens. This combines the high speed IMU values (like 500 times per second, but can drift) with the slow speed (60 times per second) values from the sensor. The sensor values can't drift, but are too slow to use on their own. Mixing both, we get stable tracking without drift.

    The touch controllers also have IMUs and do sensor tracking with sensor fusion. If you cover up a touch controller (hide it from the sensors), it will continue to work fine for a second or so, the IMU can track movement for about that long before it becomes too inaccurate (accumulated errors). Then the touch will stop moving in the game, but it will continue to rotate, because rotation is easier to track with IMUs than position. You'll get drift again, like a DK1 hmd. It will return to normal when the sensors can see the touch again.


  • Scope666Scope666 Posts: 14
    NerveGear
    Perhaps there are bugs in 1.12's "fusion" code as a LOT of people have this issue, and it's almost always the left side lower.  I've done the IMU calibration numerous times and the slant always remains exactly the same.  The really odd one is before my Rift arrived, I noticed the slant in the menus of Robo Recall using Revive, and that's a completely different headset.  That leads me to believe it's a code problem and not the HMD itself.
  • kojackkojack Posts: 5,245 Volunteer Moderator
    Hmm, if revive is doing it too (which means different hmd and tracking system), then yeah, that sounds like a software issue.


  • foresterrforesterr Posts: 22
    Brain Burst
    I think this tool won't work anymore with current version of Oculus software installed.

    Support also won't send it anymore:
    We are no longer distributing the IMU calibration tool as it is no longer an effective solution since we released the display optimization a while back.
  • Adiel79Adiel79 Posts: 4
    NerveGear
    Hi all,

    I have a question for people in the know. 

    I bought my CV1 from Amazon. It shipped from the US to my country in the Mediterranean.

    I've had many issues with my system, including this one, and this one -

    https://forums.oculus.com/community/discussion/51600/sudden-tracking-problem-all-games-unplayable-loosing-hope

    Could it be that my headset is calibrated for the US and is having issues due to the temps in my region or something of the sort?

  • cyberealitycybereality Posts: 26,156 Oculus Staff
    Yes, the way the internal IMU sensors are calibrated can be affected by the location, for example weather conditions like the temperature, etc. We have a recalibration tool that can help resolve this in some cases, but it's not a silver bullet. But it's worth contacting support to see if it will help.
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  • armoosaviarmoosavi Posts: 1
    NerveGear
    Owned a Rift for a few weeks, and just got this issue yesterday. I tried the IMU tool multiple times to no avail, and like Scope 666 noticed that the IPD adjustment screen with the "+" is perfectly level every time I try and recalibrate the device, suggesting it is a software issue.

    One thing I did notice is that it's always reported that the tilt is to the left. I looked at my Rift, laid upside down, and noticed it tilting right (i.e. to the left of the device if it were right-way up). I then realised that this is because the HMD's cable is on the left side.

    Before yesterday, whenever my Rift was not in use, I would pack it away. Yesterday was the first time I left it out, and I think it's at least partially something to do with the weight of the cable tilting the device left, and that affecting it when you subsequently turn it on.

    I tried weighing down the left side of the Rift with a Touch controller while re-running the IMU with this in mind, but that didn't resolve the issue either. Still, I don't think it's a coincidence that all these reports have the tilt being to the left to various degrees (the extent of the tilt changed for me from time to time in the past 24 hours).

    Does anyone else feel like I'm on to something here? 
  • phillabustphillabust Posts: 4
    NerveGear
    just got my rift this week. everything worked fine the first night, didn't play the second night. the third night went to play again and the whole world was tilted to the left.. to the east. when i turn around it is relatively tilted to my right. (still to the east) i was really hoping to have some VR experiences, but with the world tilted to the side... i'd rather not risk VR sickness. it's a noticable amount of tilt, feels close to 10 degrees or more.
  • simo1000rrsimo1000rr Posts: 33
    Brain Burst
    to the post above , im going on my third year of the Oculus Rift and i still my rift is tilted to the left side about 5 or so degree. it has been reported by too many oculus owners and they all reported that its tilted to the left " all of them " , The oculus guys either knows what happened and they dont want to say it or the have no clue what is going on either way that goes to tell you and everyone else not to even get close to their products anymore . its the way how they treat their costumer is so F***** arrogant that i had enough . 
    my next VR device for sure wont be an oculus . im crossing my finger with the Samsung odyssey release next month.
  • Cuda_UKCuda_UK Posts: 1
    NerveGear
    Got my Rift CV1 yesterday and i believe it was on the tilt to the left from the very start...i also can't believe this is a well known issue (that never cropped up in tons of reviews i saw) and has been for a long while it seems!? WHEN is this going to be fixed Oculus?? 
  • GuiguitoGuiguito Posts: 1
    NerveGear
    I also have this issue on a brand new Oculus. That would be great to get a solution on this. Oculus what are you doing about it ? it is really disturbing and clearly helps motion sickness.
  • deftwaredeftware Posts: 79
    Hiro Protagonist
    I just got a Rift and the horizon was level yesterday all day. It was level the first-half of today, now it's not. A little to the left like everybody else. Clearly this is a software issue if someone pointed out that playing Robo Recall via Revive on a non-Rift also had a slight leftward tilt.
  • Lupuz78Lupuz78 Posts: 4
    NerveGear
    edited January 2018
    Just got rift. And mine is also tilted to the left from the start (maybe about 5 degrees, more or less). If I had known about this before and known how long this has persisted as a common issue without a fix, I would have not bought Rift (and would have bought a WMR set instead). This needs to be fixed fast! I'm getting a bit dizzy when using Oculus because of this (and I'm not a newbie with VR - I develop VR software at my work). There absolutely needs to be some tool/ini-file whatever that allows you to make minor adjustments to the level manually.

    Edit: I will give Oculus one more chance and will get replacement unit from the store.
  • FerretsnarfFerretsnarf Posts: 1
    NerveGear
    I also just got my rift (two days ago).  As with everyone else, it suddenly has a tilt to the left.  It's enough to be unusable without quite a bit of discomfort.
  • Lupuz78Lupuz78 Posts: 4
    NerveGear
    Some update: I tested this a lot and tried to make a new camera setup with different positions for cameras. But the same problem persists. Interesting was that as I turned around 180 degrees the scene remained tilted to the same direction (right this time), but then slowly it started tilting to the left, so that when I looked in one direction, it always started to tilt left from that position. In effect, looking fast in different directions, the whole world seemed to wobble like the deck of a boat, slowly making me motion sick.
  • elbofforelboffor Posts: 2,572 Valuable Player
    Ive recently got this a lot more prominent than before.
    Gonna have to reach out to support again i think
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  • YoLolo69YoLolo69 Posts: 1,111
    Wintermute
    @Luputz78 This is based on temperatures, that's probably why you see it changed slowly. Rift have an array which compensate gyroscope errors due current temperatures of the headset. When I used the calibration tools months ago, I needed to start the program when the headset was cool and on flat surface, and the test last until temperatures raise a certain amount after a certain time. The tool fill an array of those compensation value to try to stay flat whatever temp it reach. Saying that, after this calibration I still have a few degree tilt to the left but learned to live with (it's pretty light).

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  • simo1000rrsimo1000rr Posts: 33
    Brain Burst
    edited February 2018
    Guys rest assure that they will not even bother with you , its been like that since the oculus release and they didnt bother . lets see if they will even comment here , they comment on every other topic in the Forum but they look at this topic and they turn their head the other way and continue walking :wink:
  • Lupuz78Lupuz78 Posts: 4
    NerveGear
    Yeah. Got a replacement unit. I highly doubt this is a hardware problem with Oculus headsets. So I doubt the "calibration tool" won't help at all. It's an identical problem with a different headset altogether and it really does get worse after a while when playing (hmd gets hotter?). Man this is annoying...
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