God Rays compare CV1 and DK2

[voidxno]

Have tried to make a controlled comparison video between god rays on CV1 and DK2:

https://www.youtube.com/watch?v=xasaoRXF5rU

Kind of a follow-up to the problems I tried to illustrate in this forum thread (Two and a Half problems with my CV1). Wanted to create a neutral method for god rays that can be repeated in the future on other VR headsets (read: CV2/Vive2).

My feelings on god rays and more is written in linked thread. When I notice them, they do not help with immersion. But lots of other improvements with CV1 B) And god rays will depend on scene shown in CV1.

Back to purpose of this post. Wanted to check and compare god rays on CV1 and DK2. Hadn't used my DK2 since I fired up CV1. Also create a better and consistent method. One that can be repeated in the future. Result is in video above.

My CV1 is not like yours, why?:

Before I go on. Many will probably wonder why their experience differ from this video. More or less rays. Not a pro, but this is how I see the situation after experimenting a lot.

First I though I could create a video result on YouTube that could be compared against other headsets. Nope. YouTube's recode of video, brightness/calibration on monitor viewed. Everything has an effect on how the subtle god rays effect in video is observed on the other side of the internet.

Also. The effect observed when using your own eyes inside headset is different from filming through one lens. Try to close one eye, and the god rays effect will probably be somewhat less. Using both it looks like you combine the effect in your brain. In addition we have the individual perception of how annoying the god rays are.

But the relative difference between CV1 and DK2 is not in doubt in this video (spoiler: DK2 wins). Both have been filmed under identical circumstances with same equipment. So the 360 video used in comparison can be used to either illustrate, or in a controlled setting compare two results.

One caveat. It might be possible to a certain degree to compare raw video result from filming with 100% same exposure settings. For anyone interested there is a download link further down with 12sec raw cuts from my iPhone SE recordings.

Material - 360 Video:

Last time I tried to illustrate god rays was a hassle. This time I tried to turn it around. Instead of holding CV1 headset and iPhone together and moving it all around. I made a 360 video with Blender that moves for me. Hence, I could keep the headset static on table. Concentrating on filming with my iPhone. More about technique and settings further down.

The 360 video created for this compare logic can be viewed here:
VRRayTest Video RightEye 360 (YouTube)

To really use same method as my video, use Whirligig Player with these 4K mp4 files:
VRRayTest_Videos_12aug2016.zip (Google Drive)

The scene I created in Blender is an attempt to create a somewhat identical color palette as the interface screen in Oculus Video app. Not too extreme scenario. Although it is a scenario to purposefully make god rays happen.

Technique:

Here are the basics on how I went about creating the recordings from CV1/DK2 lenses.

I taped my headset on the end of my table. So it was somewhat secure, with Oculus camera sensor able to see headset.

Got hold of the 4K right eye view mp4 file for my 360 video. Created a 20x loop edition. Started playing it in headset using the Whirligig Player. Using YouTube or Oculus Video app gave performance or resolution issues.

Prepared my iPhone SE with the FiLMiC Pro app. Locked everything I could: 1080p60, stabilization off, focus-lock, ISO550, 1/60s, EV0.00, 5000K, 0TINT. Used 1080p50 and 1/50s on DK2, gave less flicker.

Put a blanket over my head, and partly headset, to keep light out. Position iPhone, start filming. Get one whole 58sec loop of 360 video recorded.

A somewhat difficult part of filming is getting the right position for iPhone. Would have liked to have it horizontal/landscape. Not enough space, hence the strange angle. Also, it is tricky to get the iPhone camera lens in correct sweet spot for showing rays. My tip is to overexpose with ISO700 and 1/30s. Find the sweet spot for rays, adjust exposure and record.

Rendered the resulting comparison video to 30fps on purpose. It eliminated a lot of flicker and rolling effect from recorded material (i.e., 90/75/60/50/Hz/fps).

Material - Extras:

For those interested in raw video results from my iPhone SE. Here are 12sec raw cuts from CV1 and DK2 (first circle movement):
GodRaysCV1vsDK2_raw_Samples_12aug2016.zip (Google Drive)

As told above. Really had problems to get brightness correct when viewing on monitors. In addition, YouTube recode looks to darken videos somewhat under certain conditions. Or my limited colorspace/gamma skills got lost in translation 😉 Anyway. The video I uploaded to YouTube has had a 5% brightness adjustment beforehand. So to make everything transparent, and also giving a much better playback comparison video. Here are mp4 downloads of both the 5% and original video:
GodRaysCV1vsDK2_upload_Video_12aug2016.zip (Google Drive)

Thoughts:

We see all this focus on benchmarks for GPU performance tuned to VR headsets. Would really like if more time was given to the optical properties of different VR headsets. Be it god rays, resolution, lowest text readability, resolution sheet on center and edge view. A neutral comparison of those properties would sway me a lot between a future CV2/Vive2.

Equipment / Software:

Oculus Rift CV1 & DK2, Win 8.1 x64, NVidia 980 Ti (361.91), Oculus Runtime 1.5.0.

[benplace]

tl;dr There are no God rays with DK2, the Fresnel lenses in CV1 creates the effect...

[Anonymous]

Nice writeup, and I agree with you from your previous post,
"This is my biggest gripe with the whole situation. It is not prevalent in most cases. But when it's there, it's jarring as <beep>, and destroys the immersion."

The "fuzziness" created by the fresnell lenses, have another very undesired effect for me, I feel like my eyesight had suddenly deteriorated when wearing the CV1. This is not something I felt when I was using DK1, I could clearly see SDE, and the poor quality plus the latency but this is different.

It's not something I would return the product for, but it certainly scares me to use it for extended play sessions, like wearing someone else's prescription glasses. Ps. I don't wear glasses in life, and I was checked to have excellent eyesight fairly recently.

Unfortunately as you are finding it to be, most assessments of all these headsets fall into the subjective territory, and it would be nice to have a standardised objective tests on these matters.

[voidxno]

@benplace: Yup. Correct. Not the main purpose of my post though. tl;dr is a fair statement, be careful though, has been known to cause ts;dr in some cases 😉

@manu: Thanks. And I really hope Oculus reduce/eliminate god rays with CV2. If possible, depending on lens choice. Your deterioration problem sounds annoying. Wonder why you experienced it differently on DK2? Is it the fresnel lenses themselves, or some other property of CV1? I know the DK2 has a focus plane at about 1.3 meters (Oculus Source). Lots of references of DK1 being at infinity. When it comes to CV1 I cannot find an absolute answer. Many statements of identical to DK2 vs infinity. The FixIt's CV1 teardown step13 is the closest I've seen that proves infinity. Maybe focusing 1.3m vs infinity over a long time is part of the problem. Although, you do say you didn't have problems with DK1. Not easy. Opticians should really start to specialize in VR. Maybe the future is individual custom made lenses on VR headsets for each persons vision characteristics.

[inovator]

I don't get the godrays I have played chronos adrift, different space games, etc doesn't effect me in the least. I think there are alot of picky members.

[clayton4115]

inovator said:

I don't get the godrays I have played chronos adrift, different space games, etc doesn't effect me in the least. I think there are alot of picky members.

there are no picky members, it is quite obvious if you look. 

[Anonymous]

@voidxno: Unfortunately I've not used a DK2, to do a direct comparison. As you say it could be some other reason for the discomfort I experience than the fresnel lenses, can't rule it out. However I feel it's because of a clarity issue, and my eyes tire very easily when I'm using it.

Could be that the increased resolution of the CV1 causing my eyes to go out of the way to try to focus on the fine details because the image quality exceeded some threshold, in which case I would see the same issue in other headsets as well. I've not tried PSVR or VIVE yet.

I'm sure they have their best people working on issues such as this, hope they get the needed feedback to make the correct compromises. We don't want an Emperor's new clothes situation either.

When the headsets hit 4K there may not be a need for these types of lenses, if they used the lenses in order to minimise SDE/pixelation and correct the incoming image quality. But if they needed them due to screen size/ FOV and space to fit in a headset, that may be more difficult. I'm uncertain what the tradeoffs and the gains were when they chose these lenses.

I'm sure I'm oversimplifying the situation or even completely off the mark, but it's like having a low quality monitor and seeing how poor the quality is, which doesn't cause discomfort as opposed to wearing corrective lenses to fix the poor monitor quality. (I'm exaggerating to make a point, not comparing)

But in either case, the first point remains (god rays), breaks immersion at a certain level to see the virtual air around you behave like slightly mirky water, where every point light source emits these rays and makes their path visible.


I'm happy with my Rift and this is just feedback to make it better.

[voidxno]

@inovator: I accept and respect that for some the god rays is a non-issue. Kinda wish I was in that category myself. But having used the DK2 for a long time, then going CV1, it is an immersion killer for me in some cases.

@manu: Ironic but good theory about the increased resolution. Not used the DK1 myself, but the SDE must have been even more pronounced there. Hope you get the opportunity to try other VR headsets to narrow down the source of the issue.

The lens choices in future headsets will be interesting (ref 4K/SDE and so on). I'm sure many characteristics where weighted before CV1 got to where it is. Also understand why CV1 has non-removable/sealed lenses (dust/weight/construction). But I would loved having them removable like DK2. Have a good seal and dust-warranty voided if you remove then. Then we could have 3rd-party all-in-one solutions with prescription built into fresnel/not lenses. Depending on each persons preferences and eyesight.

There is actually a lot of clothes on the CV1 Emperor, but some punishment is in order for indecent exposure of rays B) Many probably reads my post as an all-out attack on Oculus. It is intended as a neutral visualization of facts. Leaving material and method for future comparisons. Mixed in with my own egocentric experience of the effect. And if it pushes Oculus a small minute amount to somewhat reduce/eliminate god rays on CV2. I would be very very happy 🙂

[whitehexagon]

I'm wondering if this issue is what is driving the sale of DK2's.  They seem to be getting snapped up on ebay at high prices still.  Is it even possible to use the nice DK2 lenses with the CV1? 

I wonder if there is a planned 'non fresnel lense' upgrade path for the CV1 to avoid the god ray issue.  Anyway I feel like I'm getting used to the issue and focussing more on content, and I'm sure developers will start to avoid scenes where the issue is more obvious, although I guess there is not much can be done about the slight blurriness.   I could picture some convex curved display panels per eye in the future, which would probably eliminate the need for lenses all together!?  And aggreed with OP about detailing more of these technical optical specs.  Although I'm still glad I went with the Rift 🙂 

[voidxno]

EDIT(25aug2016): Duplicate post of my reply on 13aug in thread. Hmmmm. This forum works in mysterious ways. Sorry about that.