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acoleman
New Participant
January 20, 2015

What exactly does changing IPD do?

Does changing the IPD simply change how far apart the virtual cameras are in Unity?

I haven't been able to find anywhere that states exactly what the Oculus Rift does with the IPD value.

Do they take into account the fact that the user's eyes won't be looking directly through the center of the lens?

Do they use the IPD value to attempt to correct the refraction that looking through the sides of the lenses would cause?

Or is the Oculus Rift not that complex?

Basically, does IPD simply change the distance between virtual cameras or does it do more than that?

I want to be able to change the IPD in real time, and I think I found a way to do that. But I'm not sure if there's anything else Oculus does that I'm not taking into account.

Any help is appreciated. Thank you!
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    6 replies

    cybereality
    Inspiring
    January 20, 2015
    Yes, it should change the distance between the cameras.

    It also measures the eye relief (depth of the eye) which affects the distortion and field of view.

    It's recommended you accept the values from the profile and not try to mess with this manually.

    The only instance were it could be OK is if you were making a growing/shrinking game (like Alice in Wonderland or whatever). Then it may make sense to do this. Otherwise you may be making more trouble for your users if they adjust the values to uncomfortable levels.
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    acolemanAuthor
    New Participant
    January 21, 2015
    Thanks for the reply.

    Does it take into account the fact that the person is not looking through the center of the lens?
    cybereality
    Inspiring
    January 21, 2015
    Yes, I think that is accounted for (but please don't quote me on that).
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    brantlew
    Participant
    January 21, 2015
    Yes and no. Changing the IPD may change the boundaries of the eye renders to adjust for asymmetrical FOV. But it does not change the center of the rendering with respect to the lens. The optics handles that instead. If you offset your eye from the center the lenses will "magically" keep the rendering centered for you.
    acolemanAuthor
    New Participant
    January 22, 2015
    What do you mean by "magically" corrects for it?
    brantlew
    Participant
    January 23, 2015
    "acoleman" wrote:
    What do you mean by "magically" corrects for it?


    It's a property of collimating lenses. Light from the center pixel radiates outward toward the lens, but once those rays traverse the lens they are all traveling in parallel. So no matter where your eye is positioned the center pixel will look like it's straight in front of you. It appears to move right along with your eye. Magic. :)

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