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    #31
    Originally posted by Tom Sarkanen View Post
    It may have passed some people by as it was not called out prominently in the 4.15 release notes, but with 4.15 LOD calculations were changed, not to allow LOD based on distance, but to allow LOD "screen sizes" larger than 1.
    The current calculations use a "screen size" metric that amounts to the screen-space diameter of the projected bounding sphere of the object. In this way, we get camera-angle and screen resolution-independent LOD calculations and *also* handle large/nearby objects.
    How should the LOD be handled in VR? One issue I have with screen size is that for every eye the object might have a different screen size, so the left eye can see a different LOD than the right eye, and that looks very wrong.
    Easy to use UMG Mini Map on the UE4 Marketplace.
    Forum thread: https://forums.unrealengine.com/show...-Plug-and-Play

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      #32
      As I understand it, in VR the screen size is calculated once (although I cant remember whether it is the left or right eye, I dont suppose it matters). Otherwise you get horrible sickening effects where objects end up with two LODs at the same time.
      Tom Sarkanen | Unreal Engine Developer | Epic Games UK

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        #33
        Originally posted by Tom Sarkanen View Post
        As I understand it, in VR the screen size is calculated once (although I cant remember whether it is the left or right eye, I dont suppose it matters). Otherwise you get horrible sickening effects where objects end up with two LODs at the same time.
        I am seeing exactly these horrible sickening effects, so for some reason it is not working correctly. Are you sure it should only calculate LODs once, even with Instanced Stereo Rendering disabled?
        Easy to use UMG Mini Map on the UE4 Marketplace.
        Forum thread: https://forums.unrealengine.com/show...-Plug-and-Play

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          #34
          Ah, this may be my bad - there was discussion of this internally pre-GDC as a fix was made for the VR Editor. I'm just trying to trace whether these changes got merged back over. Suffice to say, in 4.15 there is a bug where per-eye you can end up with different LODs being calculated.
          Tom Sarkanen | Unreal Engine Developer | Epic Games UK

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            #35
            Thanks!
            Easy to use UMG Mini Map on the UE4 Marketplace.
            Forum thread: https://forums.unrealengine.com/show...-Plug-and-Play

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              #36
              Hmm, on tracing this I found that we were seeing this artifact only when we were using a different FOV for each eye (this was for a crazy internal hack). Could you submit a bug report to the AnswerHub if you are just getting this issue in a regular VR project?
              Tom Sarkanen | Unreal Engine Developer | Epic Games UK

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                #37
                Originally posted by Tom Sarkanen View Post
                Hmm, on tracing this I found that we were seeing this artifact only when we were using a different FOV for each eye (this was for a crazy internal hack). Could you submit a bug report to the AnswerHub if you are just getting this issue in a regular VR project?
                Hm, strange. Already hoped you could just point me to the fix and I could easily merge it.

                I've created a bug report now: https://answers.unrealengine.com/que...ods-in-vr.html

                Also uploaded a repro project there.
                Last edited by John Alcatraz; 04-03-2017, 05:08 PM.
                Easy to use UMG Mini Map on the UE4 Marketplace.
                Forum thread: https://forums.unrealengine.com/show...-Plug-and-Play

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                  #38
                  Found it!

                  The fix is ready to go into Main this week from the Dev-VR branch. Hopefully it should hit by Friday.
                  Tom Sarkanen | Unreal Engine Developer | Epic Games UK

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                    #39
                    Originally posted by Tom Sarkanen View Post
                    Found it!

                    The fix is ready to go into Main this week from the Dev-VR branch. Hopefully it should hit by Friday.
                    Awesome, thanks!

                    I hope its possible to easily merge it back into 4.15.
                    Easy to use UMG Mini Map on the UE4 Marketplace.
                    Forum thread: https://forums.unrealengine.com/show...-Plug-and-Play

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                      #40
                      Nice work folks, this certainly curbs my issue and prevents a nasty shader setup.

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                        #41
                        Originally posted by Tom Sarkanen View Post
                        The fix is ready to go into Main this week from the Dev-VR branch.
                        For anyone reading through this, I have tested the fix and it does in fact fix the issue, but only with static meshes unfortunately. I actually never saw this issue with static meshes in my game, since I just don't really have any static meshes with LODs. Where I am seeing this issue is with foliage, that's where LODs are most important.

                        Foliage are not static meshes, they are HISMCs, and HISMCs have their own LOD calculation that was not touched by this fix

                        So HISMCs still show different LODs per eye. What I'm often seeing is that left eye shows a mesh, and right eye shows the billboard of the foliage, which is extremely visible since the difference is so huge. This was entered as https://issues.unrealengine.com/issue/UE-43763 I think, its not public though, if anyone could make it public that would be nice.
                        Easy to use UMG Mini Map on the UE4 Marketplace.
                        Forum thread: https://forums.unrealengine.com/show...-Plug-and-Play

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                          #42
                          Still request this feature.. we are doing some multi screen projects, and the LODs on adjacent screens are different for one object since they are always not the same screen size on different screens... Or could anyone give me some direction which part of the code I should look into? Thanks very much!!

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                            #43
                            Originally posted by Tom Sarkanen View Post
                            As I understand it, in VR the screen size is calculated once (although I cant remember whether it is the left or right eye, I dont suppose it matters). Otherwise you get horrible sickening effects where objects end up with two LODs at the same time.
                            I'm running HP Reverb, which has the highest resolution on the market currently, and even if I put everything in lod group HighDetail, it still looks super jaggy, so I have to run with LODs off, which is terrible for performance in a datasmith imported CAD scene.

                            Am I missing something has VR technology moved forward faster than Unreal has had time to catch up?

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