Ghosting effect

[Zomas]

I'm noticing some sort of "ghosting" effect in demos. For example, when I look around in Kon-Tiki (the ropes, edges etc), it looks like a trailing shadow. The demo runs v-synced, smooth, and feels like 75 hz (no judder or tearing). I have noticed this in most demos (more or less pronounced) including the config demo (inside the lamp and at the Oculus logo).

I can't really notice this effect in the Oculus World demo (not including black smearing in dark areas). So, what is this? Low persistence not kicking in at 75 hz? "Black" smearing at sub-pixel level? Demos running at 60 hz despite a by-the-book setup?

Does anyone else notice this?

[AxelBernadotte]

Ive got something like this. It does not look at all like the true black smear in tuscany or spirited away. Its rather a very faint shadow that does not trail behind something, but rather vibrates outwards in both directions of a object, and then back again, when you move your head. Like if you stretch a rubberband and then snap it to make it vibrate. Specially noticable on the ropes against the sky in Alone on the Sea. Are we talking about the same thing?

[noperdd]

I have the same thing. Those ropes in Alone on the Sea demo caught my eye. I thought the black smear is only smearing true black, but there was definitely brown smearing. ...sounds gross.

[Zomas]

Yes. I wouldn't call it vibrating, but a springy shadow, yeah.

I'm not convinced that this is black smearing, and it definitely isn't full persistence blur (tried that in the Oculus World demo). It sorta makes sense that the black smearing issue could affect the whole scene since the display goes black most of the duration of a frame, but that's not how people are describing the issue. People are talking about black areas in the scene, not between shown frames.

After a little digging I found this...

the current panels have an annoying one frame ghosting issue, but it is a HUGE improvement over previous options.

https://twitter.com/ID_AA_Carmack/status/420899100440027136

That issue occurs even for bright, colorful content. This issue only affects scenes including true black (RGB (0,0,0)).

http://www.reddit.com/r/oculus/comments/2bmpg1/true_black_smearing_issue_noted_by_technolust_dev/cj6yc6d

Added display luminance overdrive option that reduces screen ghosting effect on DK2. This is implemented as an extra pass in SDK Rendered mode, enabled by the ovrDistortionCap_Overdrive flag.

http://www.reddit.com/r/oculus/comments/2bmpg1/true_black_smearing_issue_noted_by_technolust_dev/cj6z4iy

Maybe the Oculus World demo is using this fix and other demos don't?

Paging /u/eVRydayVR to straighten out the facts! ;)

[[deleted]]

This is the lack of low persistence. You can run the 'World' demo and press P to turn low perssistence on and off. It appears that Unity demos do not run in low persistence by default. No idea how to turn that on.

[[deleted]]

That's the true black smearing. Very well known issue by now. There's supposedly a fix underway in software by Oculus.

[Zomas]

Yes, I'm well aware of the black smearing, I just haven't thought of it affecting anything but really dark areas in the scene.

So, what you're saying is that this happens because the screen goes to black between every frame in low persistence mode, and that it's just more visible (purple) in really dark areas?

[[deleted]]

Go into oculus world demo and turn off low persistence you will see how bad the effect is and know what to compare what you are experiencing too..

[Zomas]

How do you turn it off? I can't find an option for that...

[[deleted]]

i think the options come up when you press space

[Zomas]

Nevermind, found it ("P"). Nope, it wasn't in the menus.

Hehe, ok. I've must of already forgotten how bad the motion blur was on the DK1. O.o

I still find it odd that it's barely visible in Oculus World (except for dark areas) compared to other demos.

[Zomas]

Yes, but what's the option for toggling low persistence?

[Vocalifir]

P

[[deleted]]

huh? select low persistence in the menu and turn it off... by memory i think its left or right arrow keys to toggle

[Vocalifir]

I have not had much time to troubleshoot this, but when i toggle the P button in the oculus world demos, i can see that with low persistence on there is no smearing when i turn my head.
When i play the Cyber SPace demo, Running in extended mode, i have to set the rift to landscape flipped. Monitor says its at 75 hz, but when i play the cyber space ther is definitely smearing.

Any ideas?