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Reversed Stereoscopic for the Daydream?

Discussion in 'Daydream' started by Freaking-Pingo, Feb 15, 2017.

  1. Freaking-Pingo

    Freaking-Pingo

    Joined:
    Aug 1, 2012
    Posts:
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    Hi Daydreamers,

    Could someone explain to me why the stereoscopic view of the Daydream appears to be different than how our eyes naturally see things? I would expect object visible to the right eye to appear more to the left, and objects to the left eye appear more to the right, similar to the explanation given below. I feel like I am missing something fundamental. I have been searching on google on various VR screenshots and some of the seem to follow my explanation while in other cases it don't. Could someone elaborate on this? Maybe point me towards some resources that explains this?

    How we perceive objects in real-life.


    Example from the Daydream. I would expect the right eye's box to appear more closer to the left border while the left eye's box should appear further away from the border.


    An illustration that I believe explains how I expected it to be perceived
     
  2. joejo

    joejo

    Unity Technologies

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    May 26, 2016
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    Just to clarify, is this in editor or on device?
     
  3. TimurB

    TimurB

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    Oct 12, 2016
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    Judging by settings icon size it is from editor.
     
    Last edited: Feb 16, 2017
  4. Claytonious

    Claytonious

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    @Freaking-Pingo , I think you have it backward. You said:

    But if you look at your own "How we perceive objects in real-life", that's the opposite of what's happening. Substitute the distant house for your cube. The same thing is happening to the house in your image and the cube in Daydream, ja?
     
  5. TimurB

    TimurB

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    You should substitute hand with the cube not house. Distant house on the pictures remains stationary.
    https://en.wikipedia.org/wiki/Parallax
     
  6. Jodon

    Jodon

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    Sep 12, 2010
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    Hello,

    I'm fairly certain the eye transforms are reversed. I've filed a bug. If you search on Google Play for Cardboard apps, you will notice that the screenshots (built with an SDK before Unity integration was available) all mimic what you would expect in the real-world.

    Case 881874

    Edit: Actually on certain apps mimic what you would expect. Most are cross-eyed (like Unity). Check out my forum post for more details: Are Eye-Transforms Backwards?


     
    Last edited: Feb 16, 2017
  7. Freaking-Pingo

    Freaking-Pingo

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    If I am not mistaken, both the house and the finger would move to the left, but because the finger is much closer than the house, the finger is moved much further than the house.
     
  8. Freaking-Pingo

    Freaking-Pingo

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    My screenshot is from the editor, but the same occurs in the Daydream app. I even tried out the "Fantastic Beasts and where to find them" app, and there it occurs as well, using the magic suit case as a reference.
     
  9. Captain-Awesome

    Captain-Awesome

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    Jul 29, 2014
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    That is weird. Just tested right now, with my game on my phone, and with my finger in real life. And the results were different just like you said.

    I wonder if it was a mistake, or if it's a workaround to some other more serious problem they wanted to solve.
     
  10. Freaking-Pingo

    Freaking-Pingo

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    It is a good question. I am wondering what sort of implications this will have on the perception of depth, if any.
     
  11. bgolus

    bgolus

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    Dec 7, 2012
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    You're assuming the cameras' projections are the symetric for both eyes, just offset positionally, but this isn't the case. Most VR devices actually use asymmetric projections such that the left and right extents of the projection are at different angles, also sometimes tops and bottoms too.

    You can see this by putting an object directly in front of the camera, but very far away such that the effects of the stereoscopic offset aren't a factor, and you'll find the object will be slightly to the left of the expected center of the left screen, and slightly right of the center of the right screen. You'll also find if you measure their physical distance apart on the phone's display it'll be approximately 60mm. That's no accident, that's the average adult IPD, or the distance between the center of one pupil to the other.

    Basically the problem with Daydream phones, and especially the Pixel, is that average width being 60mm, or ~2.36 inches means you need to have a screen that is ~4.62 inches wide to have a symmetric projection, however the Pixel's 5" screen is only 4 inches wide, so the left and right are slightly cutoff. Even the Pixel XL's 5.5" screen is only 4.4 inches wide. This is all working like it should though.
     
  12. Freaking-Pingo

    Freaking-Pingo

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    But aren't the asymmetrical rendering opposite of how one would expect?

    Lets imagine this: If we take this mans point of view and we were to draw the "Sagittal" plane inside the Daydream, painted the letter "L" on the LEFT side and a "R" on the RIGHT side:

    • In real life: This man would observe the "L" on the LEFT side and the "R" on the RIGHT side:
    • Using Daydream: This man would observe the "L" on the RIGHT side and the "R" on the LEFT side.
     
  13. bgolus

    bgolus

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    You're misunderstanding what I mean.

    Here's a crummy doodle I did on my iPad to try to help explain.
    IMG_0030.PNG

    If you look at your original image you can see the right eye is seeing more of the side of the box than the left eye, as it should. You're just getting hung up on the box's positioning inside the display, which as I was trying to explain, isn't actually what's important. What's important is the physical relation of those pixels to your eyes.
     
    Freaking-Pingo likes this.
  14. legendaryxpictxter

    legendaryxpictxter

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    Nov 14, 2017
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    It is about the cameras/lenses.
    I discovered this issue because I shoot Cross Eye 3D with normal lenses but my friends can not see cross eye 3D.
    So I ordered Google Cardboard $5 from Ebay.
    Google Cardboard does not distort my video however!
    Because the two videos are so close to my face the correct video has to correspond with the correct eyeball.
    This means I have to switch my videos from cross eye view to parallel.
    BTW, you can not move the house or the finger because it is to late now that the virtual photos have been taken but! you can switch the 'camera placement', simply by switching the sides of the photos.
    Or perhaps even using google cardboard, you will then see the 3D effect perfect with Cross Eye viewing.
    Same with the lower example, the cube is actually resting in space 'behind' the numbers.

    I am going to copy paste some information from just one producer of this 3D VR type camera here that may help shed light on bolus's post.

    EMR Lab says,
    If you want to use this camera with the OSVR then we recommend you order the OSVR replacement lenses which provide the necessary lens corrections to work with the HD3D-lite.
    This camera works with the Sony HMZ, Skyzone SJ-H01, OSVR, Cinemizer, Dominator HD, Fatshark V3, 3D TVs and many more SBS capable displays.
    We can't show you the amazing quality of the camera online without compressing the video, EMR Laboratories, Inc.