Does size really matter?

[Si_Crewe]

I'll have to open by saying that, thus far, I've just been pottering around with this stuff on my own so I have no idea if what I'm thinking about is already well-understood and been discussed.

Thing is, I've got this nagging feeling that size, screen-size that is, really does matter, in a single-screen HMD at least.

For software to generate an image with perspective, it has to know what the user's POV is and have a "vanishing-point" for objects to be drawn from and is the point that you are, theoretically, looking toward as objects appear in front of you.

If you have, say, a 5.6" 16:10 display and, for the sake of argument, the vanishing point is in the centre of each half-screen then, as it turns out, the vanishing-points of each half-screen would be around 61mm apart, which means that, with an IPD of 65mm, each eye can look at the vanishing-point of the image in a fairly natural manner, as if the focus of your eyes is converging on an object in front of you.
Conversely, if you have a 7" 16:10 screen, and you're looking at the same image, the vanishing-points would now be 76mm apart and your eyes would either focus on a part of the screen that isn't the intended vanishing-point or each eye would have to look in a slightly different direction (think Marty Feldman) to focus on each intended vanishing-point.

By way of an exaggerated example, imagine if you made a HMD using a 15" screen.
You bolt it in front of a pair of lenses and the result is that you're going to to be staring at the extreme inner-edge of each half-screen and the vast majority of the image is going to be way out in your peripheral vision rather than in your direct line of sight.

I can't help wondering if Oculus went from using a 7" screen in the DK1 to a 5.7" screen in the DK2 simply because a high-quality 5.7" screen was available OR because they realised that a 5.7" screen (coincidentally, using a 5.7" 16:9 screen means that the centres of each half-screen are almost exactly 65mm apart) allowed for images to be viewed more naturally?

Course, there'd be nothing to stop somebody from using software to adjust the image so that the intended vanishing-point IS in an optimised position but I can't help thinking that viewing an image on a screen that's a different size to what was intended is likely to detract from the immersion and, possibly, lead to eye-strain or motion-sickness.

Ideally, it seems like you'd want software that would allow you to enter your screen size and your IPD so that it could generate an image where the perspective is all tuned to suit your own requirements.

[labmice00]

Yea, screen size matters. With a 7-inch screen, you cannot view ordinary SBS3D content since the image centers are too far apart, unfortunately.

If you look at content created for the DK1, then you'll see that the image centers are closer together than the ones for the DK2. Originally, Palmer planned to use 5.6 inch screens in the DK1 but had to settle with 7-inch ones out of supply issues.

[Bluedeath]

I am using VRPLAYER to wiev sbs content on my 7" hmd, i use sweetfx (i modified the setup that whitecanid uses for elite dangerous) to correct ipd for games when using tridef sbs.
HOpe this helps you

[Blinkstar]

I am using VRPLAYER to wiev sbs content on my 7" hmd, i use sweetfx (i modified the setup that whitecanid uses for elite dangerous) to correct ipd for games when using tridef sbs.
HOpe this helps you

Hey, I tried to do the exact same thing without success! Could I have a copy of your customized files?

[Bluedeath]

the general instructions are the same as any sweetfx installation (it also works on some other version by replacung the main.h and SweetFX_settings.txt on 64bit version tested succesfully with dying light)

The oculus settings are
set all the shadxers to 0 in the file SweetFX_settings.txt

in main.h chnage this: line to correct IPD (higher value means shorter IPD):

WHITECANID_OCULUSLENSOFFSET_X 0.05 -> line to correct IPD (higher value means shorter IPD i think i am using 0.058 (has been corrected sorry for the previous error)):

#define WHITECANID_DISTO_0 1.0
#define WHITECANID_DISTO_1 0.22 -> line to change the amount of barrel distortion (hiher means more distortion)
#define WHITECANID_DISTO_2 0.24
#define WHITECANID_DISTO_3 0

theese two lines are to compensate for lcd bezel (if needed otherwise do not touch them, i honestly do not rememnbere but i might have thesse values set to 0 on my system):

#define WHITECANID_PHONEOFFSET_X 0.002
#define WHITECANID_PHONEOFFSET_Y -0.001

let me know if you should need enything else

[Bluedeath]

i forgot you must set the FOV to 90~100° within game config files to achieve the best results

[Blinkstar]

the general instructions are the same as any sweetfx installation (it also works on some other version by replacung the main.h and SweetFX_settings.txt on 64bit version tested succesfully with dying light)

Thanks! I'll have a go with those settings. My main problem is that I could not get whitecanind's configuration to run AT ALL. And I have yet to get any SweetFX config working with Tridef-3D ... What configuration did you use to get it running with Tridef?

EDIT: Never mind about that last question--got it working with RadeonPro and an injector. What I'm getting now is an SBS image that is too converged, for lack of a better term--instead of two nearly identical images with a slight shift, it's more like a single image split in half, with the middle of the image missing ... Not sure which parameter could correct for this? Also--if I use it with Tridef, then I get four images, because it looks like SweetFX is already splitting the image, just not correctly ...

[brantlew]

This only matters if
1) Your left and right views are equally spaced and you cannot change the stereo center of the images or
2) Your cannot center the lenses on the stereo centers of the images

If you can do either or both those things (especially 1) then screen size is irrelevant for stereo fusion. Most HMD's at least do 2. Since the Rift uses it's own SDK and can adjust the placement of the rendered images it does both. So screen size was not chosen for purposes of stereo fusion. As an example, the DK1 and GearVR for S6 screens are nearly 2 inches different, yet both products can easily be stereo fused.

[Bluedeath]

Did you correctly setup ddd for sbs? Lower the oculus offxet x value put 0.058 (i wrote 0.58 by mistake)
Btw you should also deachivate postprocessing shaders that atr builtin the game.

[konstantin_lozev]

This is indeed an issue and the Durovis Dive plugin has a setting for 7 inch tablets that brings the center of the screen closer. I have wider than normal IPD, so I can view any SBS image on my 7" tablet with a modded plastic holder, but some people that have tried it say the two parts of the screen cannot converge for them.