Author Topic: Two players on one screen (no splitting) ?  (Read 3929 times)

Offline Vicomte Raf

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on: February 09, 2008, 07:39:28 AM
Hi everyone !

I'm not an engineer, so I'm not sure about the feasibility of what I'm thinking right now.

Supposing you want to have two players playing on the same screen and sharing the same 3D VR experience.

Can't you combine the polarized glasses idea with the old LCD shutter glasses technology ? This way, the screen would play the images this way :

- Image 1 :
Player 1, left eye (horizontal)
Player 2, right eye (vertical)

- Image 2 :
Player 1, right eye (vertical)
Player 2, left eye (horizontal)

I know it's a bit more on the hardware side, but I'd like to know if you think this could be done.  ???

Offline brentrs

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Reply #1 on: February 09, 2008, 03:14:55 PM
Check this out:

Seems to be just about what you're talking about, with just one variation; instead of two images with one for left eye and one for right eye, why not image 1 for person 1 and image 2 for person 2?!  You lose the 3D imaging, but still have head tracking for each person. I think this would be a completely easy project, assuming that the refresh rates are good enough to fool someone's eyes.  In fact, if the refresh rates were phenomenal, I bet you could consider more that 2 people at a time on 1 screen.  sort of like this:
3 people, so 3 frames per (some time frame)

           Frame 1    Frame 2   Frame 3
person 1     on         off       off
person 2     off        on        off
person 3     off        off       on

Lather, rinse, repeat. 

Offline Vicomte Raf

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Reply #2 on: February 09, 2008, 05:45:54 PM
Thanks for the link :)

Actually, I was thinking about head tracking for my proposition too. The advantages of it being 3D (of course) and the two brains getting an image at every instant (once left eye, once right eye). The refresh rate would be lower too.

I admit it would get trickier with more than 2 players though.

There is an interesting article about a cellophane-based polarization for LCD screens there :

Offline c-cool-la-vie

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Reply #3 on: March 09, 2008, 03:17:10 PM
Hi you all,

Glad to see that we're getting closer and closer to easy and universal 3D display and 3D interaction between humans and screens.

The problem of polarized light is that when you add a polarizer, it "projects" the initial light direction onto the filter direction.

Well, it means that you can display only 2 "INDEPENDENT" pictures (orthogonal projection).

- 1st Statement : Problem of LCD screens is that the light is already polarized. Polarizers diminish the screen light by the projection factor (cos(alpha) where alpha is the angle between initial and new directions). It could work with any screen.

- 2nd Statement : If you display two independent pictures, then you can't send one to a player and another one to another player UNLESS your polarization filter turns 90 at screen frequency - 60 Hz for laptops. Make a polar filter turn is quite hard...

So you have a few options :

You can split your screen in two parts, one on top, one on bottom, for each player, then split each part in two parts, one polarized diagonal left, one diagonal right (for LCD). Each player has polarized glasses with ir lights. Each player can then see his OWN TRACKING AND HOLOGRAPHIC 3D PICTURE of 1/4 screen size (but proportions are good !). Good glasses could do a little zoom, but you need HD to make it feasible.

You can split your screen in two tracking parts. Good for panoramic images, but no holography.

One player only : you can make either a FULL SCREEN tracking image but non holographic (Desktop VR), or a HALF SCREEN en 3D holographic and tracking image