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SSR HDRP & VR

Discussion in 'High Definition Render Pipeline' started by olavrv, Jan 11, 2021.

  1. olavrv

    olavrv

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    SSR in our project, takes around 1ms, and when in VR it takes 3-4ms. In my naive mind, it should take around twice as much in VR, it it takes 3-4 times as much.

    Anyone?
     
    olavrv, Jan 11, 2021
    #1

  2. fabien-unity

    fabien-unity

    Unity Technologies

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    Hi,

    Can you give more details about the resolution used in both cases ?

    What really matters is the total amount of pixels rendered but VR devices are configured to display a very large resolution by default (both SteamVR and Oculus will pre-apply super-sampling resolution with about 150% increase from actual display resolution and often end up with a total resolution equivalent to 4K or more if you account for both eyes).

    Fabien
     
    fabien-unity, Jan 11, 2021
    #2

  3. olavrv

    olavrv

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    @fabien-unity We use standard setup with Unity XR and Oculus integration packages, without adjusting anything related to resolution.

    I understand your point with 1.5 x higher resolution and raymarching in framebuffer...
     
    olavrv, Jan 11, 2021
    #3

  4. fabien-unity

    fabien-unity

    Unity Technologies

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    Ok what I mean to ask is :
    • without VR, what resolution are you using?
    • with VR, what resolution are you using ?

    For Oculus, can you check your settings here for the resolution ?

    upload_2021-1-11_10-52-48.png
     
    fabien-unity, Jan 11, 2021
    #4

  5. olavrv

    olavrv

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    For the Oculus Rift S this settings looks a little bit different:

    Screenshot Oculus Home.jpg
     
    olavrv, Jan 11, 2021
    #5

  6. fabien-unity

    fabien-unity

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    Ok, I think this setting will end up returning a resolution of 1648x1776 per eye (you can confirm by querying the display resolution from Unity or by using RenderDoc, or by using the Oculus debug tool).

    Quick math on this :
    1648x1776 x 2 = about 5.85 MP
    versus
    1920x1080 (non-VR standard HD resolution) = 2.07 MP

    With these values, we can expect the VR render times to be almost 3 times more, entirely due to the increased resolution.
    This could explain the perf numbers you're seeing.

    Does that match your setup ?
     
    fabien-unity, Jan 11, 2021
    #6

  7. olavrv

    olavrv

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    Yes, it matches our setup. So this all makes sense, nice to understand and know. Thank you very much for quick response, and taking the time!
     
    olavrv, Jan 11, 2021
    #7

  8. fabien-unity

    fabien-unity

    Unity Technologies

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    You're welcome :)
    It can be tricky.
    I'll look into making this information more broadly available !
     
    fabien-unity, Jan 11, 2021
    #8
    olavrv likes this.