A Compressive Light Field Projection System (2014) | Hacker News Reader

A Compressive Light Field Projection System (2014)

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45 pointsrthomas617 comments

Viewer independent glasses free stereograpic displays all suffer from the same problem: you need a huge number of pixels (to support viewing from N angles, you need N times as many pixels).

Yep, I was thinking about a lenslet array system with NxN subpixel under each lenslet. The subpixels are view dependent by emitting light directionally using fish eye magnification of the lenslet. For 64x64 subpixel resolution (giving you around 256 view angles), you need a total of 512 megapixels for a 1080p lenslet array.

Well yes, you need to make a new type of display. It’s not a software technique to be applied to existing displays.

The point Isn't that it needs to be new but that the new thing fundamentally is far more demanding. If you have many times more pixels per frame, your GPU has to do more work, your display cable has to have more bandwidth, etc.

Unless most of the scene is static and the camera doesn't move. Then you can do partial update and the cost is proportional to the part of the scene that moves.

I want my HoloTV and I want it now!

Apple Vision Pro comes close, but still lacks in the light-field department.

(Your pupils get lazy from using it because everything is in focus all the time).

> Your pupils get lazy from using it because everything is in focus all the time

Can you explain this to me I’m always confused when people say it. From my thinking at least - I focus on close up and then far away things in VR all the time and it takes effort. The real world is also in focus all the time isn’t it, it’s our eyes that do the focusing.

that's like asking if a tree falls in a forest kind of question.

in the real world, no not everything is in focus all of the time. i'm currently sitting 38" away from the wall, my monitor is 8" from the wall. If I'm focused on the monitor, the objects hanging on the wall are not in focus.

From a snobbish videographer's point of view, it sounds like you're living in an ENG world vs a cinematic one.

> in the real world, no not everything is in focus all of the time. i'm currently sitting 38" away from the wall, my monitor is 8" from the wall. If I'm focused on the monitor, the objects hanging on the wall are not in focus.

But that is also the case in VR so I’m not sure why one would consider “everything to be in focus” which is what my question is getting at (why do people say that). If I focus on something in VR the objects behind it will also go out of focus. Unlike in cinema where a camera has to choose what is in focus, in VR our eyes choose what to focus on just like in the real world.

That's just not how I perceive imagery shot in a flat field vs shallow depth. I've spent quite a bit of time in a VR headset with live action content. It always just feels off, even the content we acquired in 3D. The 3D helps, but it's still just off. At the time I stopped working in that field, people were just starting to talk about foveal type views. However, I think they were mainly worried about what part of the screen to render in full detail to lower the rendering requirements. It sounds like with Apple's eye tracking cameras, they might actually be closer to telling at what depth you are attempting to focus.

There's no released VR system that has more than one focal depth, so I'm not sure what you're talking about, here. Whether you're looking at something near or far away in VR, your eyes don't change accommodation (focus), but they may change vergence (difference in direction between eyes). So everything is always in focus. It's easy enough to observe - look at a near object in VR and then, without moving your eyes, concentrate on a far object and note that you can still see the detail clearly.

Interesting and seemingly overlooked multi-viewer glassesless 3D display technology.

What's a 4D light field?

Imagine capturing or controlling all the light rays in a plane (or a rectangle cut out of a plane) which ideally a light field display would do. A light ray intersects the plane at a point (2 dimensions) and is traveling in some direction (another 2 dimensions.). That adds up to 4.

Huh. So it's nothing to do with spacetime. Thanks.

https://en.wikipedia.org/wiki/Light_field#The_4D_light_field

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