Vive- The depth of space.

CMDR Muy Bien Gato · May 18, 2016

Welp, I've finally plunged into VR and it's simply amazing! The perception of actually "being there" is criminally understated, and I poured over reviews and previews and hands-ons since the very first Oculus announcement. This is a reaaaally cool time to be alive.

Having said that, I naturally feel inclined to nitpick about one thing. I popped into Elite for a little bit after gushing over room scale games for what felt like an eternity, and one thing felt especially off... even more-so than the shimmering, aliasing, or weird text (which isn't that weird at all in Beta 5).

I'm having a real difficult time feeling the vastness of space. While flying around, I noticed that the stars feel kinda close. This was especially noticeable when I was hunting in a RES and my target would launch his/her chaff. At a distance, the chaff seemed to almost blend in with the stars. It was almost as if the depth of space only extended to about 3km. I guess the easiest way for me to describe it is that the vastness of space feels a little "skyboxy". Again, the overall experience is breathtaking, but when you're immersed in an alternate reality, you definitely tend to notice these things.

Is this a particular trait to the Vive? Am I just crazy? Anyone with both care to chime in perhaps?

shadragon · May 18, 2016

You've heard of the "bubble" right. That's it.

But seriously, I haven't perceived the stars as being close, but they are a little fuzzy and indistinct to me. As the tech matures I suspect that will improve which should help immersion dramatically.

Darkfyre99 · May 18, 2016

Considering the ancients were convinced the "firmament" was low enough that you could climb a mountain and touch it, or build a tower or ladder to reach it, I haven't really noticed anything off about that, though I've only had my Vive less than two weeks.

Our monkey brains determine depth via parallax, and the stars are so far away that we can't pick that up. It could very well be that without a common frame of reference, like a nearby mountain or a horizon, our brains simply default extreme distances as a couple of kilometers.

Don't forget how much larger the moon and sun appear when they're near the horizon.

BigDuke6ixx · May 18, 2016

shadragon said:
You've heard of the "bubble" right. That's it.

But seriously, I haven't perceived the stars as being close, but they are a little fuzzy and indistinct to me. As the tech matures I suspect that will improve which should help immersion dramatically.

As has been explained elsewhere, ED's representation of space is based on deep sky astrophotography, whereby light levels are way beyond what the human eye can actually see. When you blow up a deep sky image to fill a VR POV you end up with fuzzy stars.

Dar|{cyde · May 18, 2016

I'm on a Rift, and never noticed this. I've heard several reports of Vive users saying that space feels like a physical backdrop at various distances, basically what you're say. I don't know what. Maybe something to do with the focus depth of the Vive? AFAIK its not set to infinity like the CV1?

Captain N · May 18, 2016

Human stereoscopic depth perception doesn't extend much past 200m, so it isn't surprising if chaff at 3km seems to blend with the stars.

I'd be more worried if you could sense the depth with things like planets, stars and far away stations, since that would mean the scale is way off.

A happy Vive owner here.

stripealipe · May 18, 2016

I've actually raised a ticket about this, as space definitely does feel properly vast in my DK2 compared to the Vive, which is disappointing.. There is simply a better sense of depth and scale in the Oculus implementation and there are plenty of people reporting this. I've opened up a ticket with FD regarding the scale, so we'll see if they come back with anything.

Skaldy · May 18, 2016

Surely this down to the distance between the two images that are presented to the eyes? If you get this wrong then it might look too close. This is just based on my simplistic understanding of stereoscopy.

CMDR Muy Bien Gato · May 19, 2016

stripealipe said:
I've actually raised a ticket about this, as space definitely does feel properly vast in my DK2 compared to the Vive, which is disappointing.. There is simply a better sense of depth and scale in the Oculus implementation and there are plenty of people reporting this. I've opened up a ticket with FD regarding the scale, so we'll see if they come back with anything.

Awesome! I might consider doing the same, if I can ever pry myself away from Space Pirate Trainer...

Heavenly-Hammer · May 19, 2016

Can't say I've noticed this.

[HJ]-RedRaven · May 20, 2016

FD's skybox is based on real-life, including a catologue of known stars, their positions and brightness (magnitude). It renders this starfield map onto your skybox when you jump between systems (and at the start of the game when you first load in).

FD must have to render the starfield onto some polygonal mesh (a rough spheroid, probably). Its certainly possible that this mesh is set only a few km away. It obviously will move with you, so there could be no chance of you noticing any parrallax motion of the stars, but subtle clues might give some pilots the impression that it is set at some distance (and not pretty much infinity as you would expect).

It'd be interesting to know from FD what the actual sky-box dimensions are.

Captain N · May 20, 2016

Are you sure your IPD and FOV are set correctly, anyway? Correct IPD is very important for good sense of scale and a too high FOV can make things look small.

Skaldy · May 20, 2016

Captain N said:
Are you sure your IPD and FOV are set correctly, anyway? Correct IPD is very important for good sense of scale and a too high FOV can make things look small.

Where can you set IPD? On the Vive there is a adjusting , but it only changes the distance of the lens.

I found IPDAmount in Settings.xml. But it is set to 0.001, not sure what that means?

Captain N · May 20, 2016

Not sure what you're asking here. The adjusting (on the lower right of the device) is for setting the IPD.

CMDR Muy Bien Gato · May 20, 2016

Changing the IPD doesn't change anything.

Basically, it boils down to this. When I load up the space environment in Tilt Brush, I get a feeling of vastness when I stare off into the stars. It just FEELS limitless. However, in ED, I feel as though I'm enclosed in a sphere where the distance of the stars is comparable to looking up at my ceiling. I know they are technically light years away, but my brain tells me otherwise. It's definitely not an easy thing to catch, but if you load up any other space experiences you'll notice the difference.

Load up Irrational Exuberance (it's free) and compare it to that.

dogbite · May 21, 2016

UK Rifter noted the same lack of depth with his VIVE vs Oculus Utube video https://www.youtube.com/watch?v=agrc2OmAEYg

pipper · May 21, 2016

I toyed around with the Vive SDK and noticed that the function IVRSystem::GetProjectionRaw() returns ever so slighty different values for the left and the right eye, resulting in slightly different FOV for both eyes.
( other people noticeed the same: see https://steamcommunity.com/app/358720/discussions/0/535150948617380074/ )
If you take a screenshot of both eyes (the Mirror window has an option for that) and then overlay both images in such a way that objects at infinity match up, you'll notice that one eye shows a slightly (1-2 pixels)
'enlarged' version of the sky. This leads to the stars in the left and right eye being shifted away from each other. This in turn introduces a hint for our brain that the sky is closer than it should be (at infinity, the left and right eye
must match for the skybox) and maybe this is what is causing the weird observation that people made here.

I'd suggest FD to check how they're producing the projection matrices and make sure, the left one is basically just a horizontally mirrored version of the right and does not produce different FOV for the eyes.

BigDuke6ixx · May 21, 2016

pipper said:
I toyed around with the Vive SDK and noticed that the function IVRSystem::GetProjectionRaw() returns ever so slighty different values for the left and the right eye, resulting in slightly different FOV for both eyes.
( other people noticeed the same: see https://steamcommunity.com/app/358720/discussions/0/535150948617380074/ )
If you take a screenshot of both eyes (the Mirror window has an option for that) and then overlay both images in such a way that objects at infinity match up, you'll notice that one eye shows a slightly (1-2 pixels)
'enlarged' version of the sky. This leads to the stars in the left and right eye being shifted away from each other. This in turn introduces a hint for our brain that the sky is closer than it should be (at infinity, the left and right eye
must match for the skybox) and maybe this is what is causing the weird observation that people made here.

I'd suggest FD to check how they're producing the projection matrices and make sure, the left one is basically just a horizontally mirrored version of the right and does not produce different FOV for the eyes.

If true, there would be no 3D.

pipper · May 21, 2016

The projection matrix has little to do with the IPD, implemented by a horizontal shift of the view matrix. The IPD is correctly represented by the SteamVR SDK via GetEyeToHeadTransform().
To give an example, currently the SDK reports the following values

Left eye:
left: -1.3922
right: 1.2518
top: -1.46824
bottom: 1.4697

resulting in a horizontal FoV of 105.69 deg, vertical FoV of 111.51deg

Right eye:
left: -1.2477
right: 1.4031
top: -1.4797
bottom: 1.4632

horizontal FoV: 105.81deg, vertical FoV: 111.59deg

While the difference it FoV is little, it is nevertheless there, along with a slight shift of the projection. What I expected to see is
that the right and left eye projection are a mere mirror of each other, for instance:

Left eye:
left: -1.3922
right: 1.2518
top: -1.46824
bottom: 1.4697

left: -1.2518
right: 1.3922
top: -1.46824
bottom: 1.4697