building a volumetric display

[thevesel]

This is the kind of volumetric display I'm talking about:

http://I.imgur.com/wP4UjrQ.jpg

 

Videos give a better idea and are cooler:

 

[VIDEO]

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[VIDEO]

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From the various articles I've found on the internet I now have a basic idea how to build a real volumetric display. I will link to relevant sites below.

But I cannot find info on what hardware to use to achieve 3d RGB volumes, only binary monochrome, even though some of the old products and projects I've found can do color or at least grayscale.

 

This is one of those projects I just know I have to do. I agree with one of the creators of such displays that there is no commercial and real world use for this kind of technology because of the way content for it has to be created and our mostly "paralyzed" and "single location" way of viewing visual content. This is probably a good explanation why the commercial volumetric displays like "Perspecta" which I've linked to below never became a commercial success and was discontinued and Sony's 360 degrees holographic display prototype from 2012 (second video) isn't a product yet, and maybe why "3d TVs" aren't selling so well.

But on the other hand as a 3d artist who has created video mapping content as well as a tinkerer who has two 3d printers I just have to build one.

 

The reason I posted here for help is because to do the kind of volumetric display I want to build I need to run a projector or display at few thousand Hz refresh rate (more on that below) and I've only found one "projector" which can do 4000 Hz at 1 bit monochrome even though I've found two such displays built almost a decade ago doing RGB or grayscale. I can't find any info on the internet what kind of screen or projector can do that and that's something only someone knowing how these technologies work can tell. This is why I'm posting here.

 

Now about how the volumetric displays I'm talking about work. It's called "swept volume volumetric display". if you want a 24 Hz refresh rate of a volume (a 3d frame), you can rotate a 2d screen 24 * 180 times. That's over 4000 frames per second.

180 is the number of "slices" (2d displays) the volumetric display has. Its one for each 1 degrees. 180 because 180 degree rotation of a 2d display is needed to create a 360 degree volume:

http://I.imgur.com/PhLUyrj.gif

 

Finding out how to control a 900 RPM motor is easy, displaying 4000 frames each seconds... not so much..

http://www.ti.com/tool/dlplightcrafter

http://masters.robbi...ic-display.html

 

Perspecta's specs (released back in 2005):

In it a "high speed projector" projects 198 768x768 pixel "slices" at 24 Hz on a rotating screen (rotating at 730 rpm).

The projector is a "5kHz MEMS-based". [link1] [link2]

"The slices are projected at approximately 6000 images/ s by a group of three Digital Micromirror Devices, microelectromechanical systems- (MEMS-) based spatial light modulators (Texas Instrument, Inc. Plano, Texas)." [link]

 

http://I.imgur.com/ptuLQ7C.jpg

 

http://fp.optics.ari...oSense_2002.pdf

http://www.virtualwo...ID=22&Picture=1

http://informationdi...alityStory.aspx

http://www.eetimes.c...?doc_id=1144077

http://www.macs.hw.a.../Volumetric.pdf

http://users.eecs.no...ion_Capable.pdf

 

I don't know anything about "MEMs", but the ones I found on TI's website are only fast enough (4000 Hz) for binary 1bit frames and with 8 bit they fall down to 120 Hz. However, from the videos I've seen I'm sure I'm wrong or there are better options. Here is the data I found:

"The Light Crafter", the only "highspeed" projector mentioned in one of the above builds: http://www.ti.com/tool/dlplightcrafter

 

http://I.imgur.com/LRpezNZ.png

http://I.imgur.com/LRpezNZ.png

And the link to the full manual in pdf: http://www.ti.com/li...6e/dlpu006e.pdf

 

While the top-down swept volume display ( http://gl.ict.usc.ed...arch/3ddisplay/) is monochrome, the Perspecta is RGB. Definitely not 8 bit, but not 1 bit either (7 colors with a group of 3). I don't understand what they used, even if they used a group of 3 of those. Any ideas?

And the video starting at 1:19 shows grayscale holograms, not binary BW (1 bit).

 

Perspecta was released in 2005 and the grayscale one was presented way back in 2007 in Siiggraph. Even then more than monochrome was possible.

Any suggestions what can be used or modified to work today?

 

There are two ways: projection based, or rotating a display itself. Both would work for me. I think Sony's prototype uses a rotating display instead.

 

if going the projection-based road, there are two ways, the 45 degree angled diffuser and the vertical one like in Perspecta.

1) http://I.imgur.com/2ITO7ta.gif

 

2) http://I.imgur.com/ygnHtb1.gif

 

These are all rough illustrations just to give an idea.

 

The plan I had when I first got the idea of building this was a snow globe or crystal ball looking device (pretty similar to Perspecta) displaying animated 3d scenes.

Back then I didn't even know it was possible and that such devices had already been built.

 

I have also thought of doing this with LED matrices (LED cubes) and transparent LED screens stacked on top of each other. While I'd prefer something without moving parts, both don't seem like a good option as the first one is pretty low resolution and not too transparent with all the wires and transparent LED screens didn't seem transparent ebough to stack them on top of each other and too expensive.

[david.elsbury]

Er ok? Whooosh.... :)

[IRW]

Er ok? Whooosh.... :)

 

Glad it's not just me thinking that!

:blink:

 

I think in summary, our OP is looking for a small projector that has a refresh rate of a few thousand hertz or more

The reason I posted here for help is because to do the kind of volumetric display I want to build I need to run a projector or display at few thousand Hz refresh rate (more on that below) and I've only found one "projector" which can do 4000 Hz at 1 bit monochrome even though I've found two such displays built almost a decade ago doing RGB or grayscale. I can't find any info on the internet what kind of screen or projector can do that and that's something only someone knowing how these technologies work can tell. This is why I'm posting here.

 

At least the OP is giving us some background information on the request, unlike many others...!

[thevesel]

I think in summary, our OP is looking for a small projector that has a refresh rate of a few thousand hertz or more

Yes :) Well almost, the one I linked to is not a real projector for example, it's called an "evaluation module" used by developers. And like I said if there are displays with such refresh rates, those could work too though, I would prefer projections to keep the spherical look.

I'm sure if I would just post that I need to achieve a 4000Hz or 1300Hz refresh rate everyone would ask why I would need such a thing and I'd need to post all that info anyway.

 

A group of 3 8-bit or lower grayscale projections could work too, one for Red, Green and Blue. I've tried contacting the developers of the old builds which seem to do that in their videos without luck yet.

 

If you think this is not the best place to ask this, then please suggest me a better place. The video projector forums I've checked don't talk about the technology inside those stuff, how to get them separately or how to hack and mod them.

[richardash1981]

OP could try DIY audio's projector section http://www.diyaudio.com/forums/diy-projectors/

[thevesel]

No luck there. I think after looking up some their threads that the forum is mainly about building a home projector by putting a lamp behind and lcd screen or something. Not like that's easy or anything but very specific and not requiring the technical knowledge for answering a question like mine.