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AdamsImmersive
Up and Coming
August 21, 2013

Is it normal for walls to bulge toward you a bit?

For example, the face of the fireplace in Tuscany seems to have a curve, and when you walk up to a painting, it has a bit of a curve like non-HD TV screens used to have. This becomes noticeable about 10 virtual feet away--not really noticeable at greater distances.

Is that just a known side-effect of the optics, or a sign that something is amiss?

I did make two changes today, and I feel like the bulge may be more noticeable now:

- I manually set my IPD to 69mm via ruler and mirror; the calibration tool had set me to 67.

- I notched the A cups (I have good vision) one click farther away to stop them hitting my eyelashes so much. (Out of the box the Rift was at the third second-closest notch, now it's at the fourth third.) Minor loss of FOV but not too bad.

There's no other distortion--the ground doesn't warp when I turn my head, everything feels like the right scale, etc.

Normal?

    8 replies

    cybereality
    Inspiring
    August 21, 2013
    Well the demos (like Tuscany) use a barrel warp, to compensate for the optical distortion of the Rift lenses. It sounds like maybe something is off with your configuration to make the math inaccurate. Though there are a lot of variables at work, so it's difficult to be 100% perfect.
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    AdamsImmersiveAuthor
    Up and Coming
    August 21, 2013
    Thanks. Sounds like it's might be normal or not... To gauge the severity: if you walk all the way up to a brick wall in Tuscany, the bulge feels like it's about 6 inches or so. You can see the wall "come out to meet you" as you approach.

    If something's off with my setup, would it be hardware or software? (I hit Space to verify the proper 69mm IPD while in the demo.)
    — Morgan — Mac OS X ❆ Unity
    cybereality
    Inspiring
    August 22, 2013
    Normally the lines should stay straight. I was just saying that it's possible the configuration is not optimal.

    You can try different eye-cups, adjusting the closeness of the screen, setting the IPD back to default (ie 64mm), trying different demos with different warping algorithms (like HL2).

    Hope that helps.
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    Fredz
    Up and Coming
    August 22, 2013
    Maybe you could post a video taken through one lens to show the severity of the problem.
    geekmaster
    Up and Coming
    August 22, 2013
    The bulge is from too much barrel distortion. Try reducing the pre-warp correction factors.
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    AdamsImmersiveAuthor
    Up and Coming
    August 22, 2013
    "Fredz" wrote:
    Maybe you could post a video taken through one lens to show the severity of the problem.


    Good idea. But I find that a 6-inch forward bulge spread over the size of a wall is pretty noticeable in stereo vision, but very hard to spot with one eye.

    "geekmaster" wrote:
    The bulge is from too much barrel distortion. Try reducing the pre-warp correction factors.


    That's a new one to me! I'm not finding that setting in the docs or online. Is that a hidden feature of the config util, or the Tuscany demo, or is it something I would do in code in Unity, and build myself a custom version of the Tuscany demo? (Which I plan to do anyway to make a slow-accelerating and slow-mouse newbie friendly version.)

    I was wondering if (and where) you would tell software which lens-distance notch you were using.

    BTW I see this in Riftoon and other titles too--seems to be universal in Unity apps [EDIT:} but I do NOT see this effect in Source (Half-Life 2... although I'm not yet sure I have worked through all the reams of info on getting HL2 properly configured).
    — Morgan — Mac OS X ❆ Unity
    AdamsImmersiveAuthor
    Up and Coming
    August 22, 2013
    Further testing: the B cups greatly minimize the bulge--along with switching to the closest distance notch. (I don't even totally mind the B lens's reduced FOV, since it encourages me/others to turn the head instead of just the eyes--and that keeps people looking at the "good" part/middle of the image more of the time. And despite my good vision, the B cups work fine. I tend to think the B's should be the DK's stock default--along with brightness 0.)

    I'm glad, because my Rift game has a lot of large flat surfaces close to your face. Weird bulging is a distraction I'm pleased to avoid!

    EDIT: My limited brain has slowly processed the difference between changing cups vs. adjusting the distance knobs. Both change the distance from lens to eye, but the cups also affect the distance between lens and screen. The implications of which I am left to ponder... but in any case it works well for me now!
    — Morgan — Mac OS X ❆ Unity
    Knitschi
    Participant
    August 25, 2013
    I experience the same problem. But I haven't really searched for a sollution yet. I have a rather large ipd (7.2 cm) and use B cups with the screen distance maxed out so I dont see the inner borders of the screen.
    I will try to minimize the screen distance an see if it helps.
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