VR scene inspection - rendering artifacts on geometry only occluded for one eye with viewport denoising #76003

System Information
Operating system: Windows-10-10.0.18362-SP0 64 Bits
Graphics card: GeForce RTX 2080 with Max-Q Design/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 442.19

Blender Version
Broken: version: 2.83 (sub 13), branch: master, commit date: 2020-04-20 02:11, hash: 23bb42a06e
Worked: -

Short description of error
Trying out the new VR scene inspection feature, I noticed the following rendering artifact:

There is a faint duplicate of objects in the foreground visible to the right and to the left (depending on which eye) in front of other objects if Eevee viewport denoising is enabled.

Basically what seems to happen, is that the part of the scene that is occluded by an object in the foreground from the perspective of one eye but is visible from the other eye, is not rendered (or denoised) the same way as the rest of the scene. This goes for both eyes. This partly occluded area looks somewhat different, more pixelated, maybe a bit darker and surface reflections look different.

On a side note, the BlenderXR implementation from Marui plugin doesn't have this problem.

Exact steps for others to reproduce the error

Activate the VR inspection addon.
Start VR session on any scene.
Renderer should be Eevee, with viewport denoising turned on.
Look at an object in the foreground, while having some other objects behind it, further away.

Added subscriber: @ZsoltStefan

Here's how it looks like. To the left of the lamppost is this weirdly rendered area.

Added subscriber: @iss

@ZsoltStefan is this reproducible without VR headset? I don't have one and I am really not aware of this is possible without one.

@iss The bug can only be seen in the VR session, so you'd need a way to emulate a VR headset. An internet search led me here: https://docs.microsoft.com/en-us/windows/mixed-reality/using-the-windows-mixed-reality-simulator , this might work.

Added subscriber: @JulianEisel

Would consider this a low-priority issue. After all it's a visual only glitch, and a very small amount of users will ever run into it I think. This might also be hard to debug I'm afraid.

Changed status from 'Needs Triage' to: 'Confirmed'

Added subscriber: @ankitm

Added subscriber: @fclem

@JulianEisel Is that because you render both eye with the same GPUViewport? Thus having only one history target that is constantly being swapped for each eye. If so I would recommend duplicating the GPUViewport to avoid this but I see that it would increase VRAM consumption quite a bit.

Added subscriber: @MadMinstrel

Look, it's not helpful to call this just a visual glitch. Unlike on a monitor, in a VR session, visual glitches cause considerable discomfort, especially when it's a discrepancy between eyes.

I've been playing around with the experimental XR-actions build, and this bug is still present.

With Viewport Denoising turned on, objects in the foreground cast a ghost on the background. As @MadMinstrel wrote, "just a visual glitch" is a big thing in VR, as your whole viewfield in VR is basically a HUGE 3D viewport.

Changed status from 'Confirmed' to: 'Resolved'

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VR scene inspection - rendering artifacts on geometry only occluded for one eye with viewport denoising #76003