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Question about VR performance, pixels and comparing that to a flat monitor

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    Question about VR performance, pixels and comparing that to a flat monitor

    Hi all,

    I had a quick question. Does VR take more computing resources at a given resolution then a standard flat monitor with all other setting equal? For example lets say you had a VR headset that used a single LCD screen @4k (2k allocated for each eye) and compared that performance to a 4k flat monitor. Is it reasonable to expect the performance to match? How about if you start to lower the resolution of both displays and get into a more a CPU limited scenario? Do we see VR taking more CPU resources?

    Cheers,

    Mathieas

    #2
    It is something like that. You need resources like for 4K resolution on 90 FPS. Minimum FPS should be 45 but still, clarity is not comparable with the monitor but not the whole experience because it is real 3D and monitor is not and in VR you are inside of the plane and on the monitor, your plane is inside a frame. Performances side it is like 4K on 90FPS.

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      #3
      VR needs near double the horses than the pancake version. But VR is just on another level of immersion, you are in the cockpit flying the aircraft looking out at the world through your canopy. A flat screen is a non runner imo.

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        #4
        Yep you can figure for performance in VR it will be roughly half of of the fps you get on monitor.
        Don B

        My VKB Gunfighter MK III Pro L Review
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          #5
          Agreed,
          When I first got my VR driver system, in pancake I ran 130 fps down las Vegas strip with my old I5 system settings (60 fps originally).
          Slipping over to VR with the same settings I got 60 fps.
          Eventually I settled with 45 fps (locked) as a good compromise.

          It is a very expensive gamble.
          But once VR is experienced firing on all cylinders with all your cash and soul thrown in...... there is no gamble it is just fabulous!
          The cockpit is great but the 15 feet tall trees are awesome to this chopper pilot!.
          Its all in Bud ....... cutting edge and all that sh*t.
          Been waiting 30 years for this one.

          HP pro Reverb.

          Current settings:
          Windows VR setting: IPD is 64.5mm, High image quality, 90Hz refresh rate.
          Steam: VR SS set to 100%, motionReprojectionMode set to "motionreproduction" and Locked in at 45 Hz display,
          DCS: Pixel Density 1.0, Forced IPD at 55 (perceived world size), 2 X MSAA, 0 X SSAA.
          My real IPD is 64.5mm. Prescription VROptition lenses installed.
          VR Driver system:
          I9-9900KS 5Ghz CPU. XI Hero motherboard and 2080ti graphics card, 32 gigs Ram 3200 Hz. No OC at the mo.

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            #6
            Originally posted by Mathieas View Post
            For example lets say you had a VR headset that used a single LCD screen @4k (2k allocated for each eye) and compared that performance to a 4k flat monitor. Is it reasonable to expect the performance to match?
            Doesn't work like that because VR is rendering with two cameras. Flat is one camera. It's not just number of pixels but all calculations such as occlusions, draw calls, transparency, reflections, post process... will be calculated twice. For example, reflection you see through your right eye has to be different than your left eye in order to have depth.

            Resolution will be a simple multiplier in each cases. But for VR, it will multiply 2x. So 4K VR will cost you a lot more than 4K flat monitor.

            Comment


              #7
              Thank you all for the responses.

              Taz,

              Those processes sound more like GPU tasks then CPU ones. Is it reasonable to assume these would impart further GPU limits but CPU limits would be similar? or does it really impact both about the same?

              Mathieas

              Comment


                #8
                Originally posted by Mathieas View Post
                Thank you all for the responses.

                Taz,

                Those processes sound more like GPU tasks then CPU ones. Is it reasonable to assume these would impart further GPU limits but CPU limits would be similar? or does it really impact both about the same?

                Mathieas
                It would impact GPU more but still does effect CPU as well. Draw call for example, CPU has to request that draw call to GPU because your camera position is calculated by CPU. And it now has to request twice.

                Comment


                  #9
                  Yeah, more or less take your pancake mode frames, Divide by 2, and then assume it will be 10-20% worse than that for VR frame rate, this is assuming pixels are similar.
                  New hotness: I7 9700k 4.8ghz, 32gb ddr4, 2080ti, TM Warthog. TrackIR, HP Reverb (formermly CV1)
                  Old-N-busted: i7 4720HQ ~3.5GHZ, +32GB DDR3 + Nvidia GTX980m (4GB VRAM) TM Warthog. TrackIR, Rift CV1 (yes really).

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                    #10
                    If we just would have a working dual-GPU for VR, that we could have one GPU for left eye, second GPU for right eye.
                    That would balance the VR performance nicely, but it just isn't possible so effectively. One could buy cheaply a two 1060 cards for VR and have great performance, but
                    i7-8700k, 32GB 2666Mhz DDR4, 2x 2080S SLI 8GB, Oculus Rift S.
                    i7-8700k, 16GB 2666Mhz DDR4, 1080Ti 11GB, 27" 4K, 65" HDR 4K.

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                      #11
                      Originally posted by Fri13 View Post
                      If we just would have a working dual-GPU for VR, that we could have one GPU for left eye, second GPU for right eye.
                      That would balance the VR performance nicely, but it just isn't possible so effectively. One could buy cheaply a two 1060 cards for VR and have great performance, but
                      You would still be limited by your CPU though
                      Velocity Micro PC | Asus Z97-A | i7-4790K 4.7GHz | Corsair Liquid CPU Cooler | 32GB DDR3-1600MHz Memory | EVGA RTX 2080 Ti XC | 240gb Intel 520 Series MLC SSD | 850 W Corsair PSU | Windows 10 Home | LG 32UD99-W UHD Monitor | Bose Companion 5 Speakers | CH Fighterstick | Ch Pro Throttle | CH Pro Pedals | TrackIR 5
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                        #12
                        Divide single screen frame rates by 3. That should give you a good estimate of your VR frame rates.
                        Derek "BoxxMann" Speare
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