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Cheaper method for 3D screen

Hey everyone.  I am new to instructables but you guys have really inspired me to see what I can come up with.  By taking a few ideas I have come across on the net, around here, and a quick epiphany after watching a 3d movie, I have an idea.  (sorry for post formatting, still trying to figure this out)

I am trying to pull the parts together right now but if someone could build it first they could have the instructable.  Well, to the idea then.  Basically, using 2 ideas from Johnny Chung Lee(a grad from Carnegie Mellon University) that he has released to the public with software(found at johnnylee.net), any 2 digital projectors, and several polarized glasses received from movie theaters you can build your own 3d projection system with eye tracking to add perspective.

The two projects of johnny Lee's we are using are Wii-mote eye tracking and Projector Stitching.  Projector stitching will be used to automatically calibrate the projectors to perfectly overlap so the offset images are accurate(absolutely critical for 3d images) so we don't have to and the eye tracking would be used by software to add perspective to any live 3d environment/game(not necessary).  The polarized glasses are used both by the projectors and the user so atleast 2 pairs would have to be acquired. 

Lenses are placed in front of the projector to filter out all but the correct pole of light.  This will dim the projector slightly as light is being lossed but what you get is cheap polarized image.  I have tested this and it does work if you project light through the back of the lens(the eye side). 

The only thing that presents a problem is the projection surface.  Most surfaces scatter and remove polarization from light.  The screens at movie theaters are specially made to not do this.  I am still researching a cheap material that has this property so I can use it but if any of you find it first have at it.  I just want the instructable up so we can see what we can do with it. 

What you get with this setup is two overlapping images that can be filtered effectively between the two eyes.  This is what enables a 3d image to be sent.  Add in the eye tracking and you have a 3d image that adjusts based on the position of the users head.  This adds an amazing degree of interactivity to a 1 player game as now you have depth added to the experience and moving actually does something for the game.


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elumley6 months ago

You can get cheap polarized filters from: http://www.polarizingsheet.com

lofty7 years ago
 Nice to see someone else is doing this =)

I've done some research into this starting with tin foil which works alright but creases easily.
My final design (or so far, i might change it) is hardboard (or any other smooth surface), spray paint with primer, then matt black twice then metallic silver.

The matt black prevents any light that passes through the silver from being reflected back with a different polarization.

There are commercially available paints for silver screens but they are expensive.

www.polarization.com for filters, don't put filters too close to the projector lens as they will melt quickly and lose their ability to polarize light.

http://forum.iz3d.com a good 3D forum i'm a member of, i have one of their 22" 3D monitors too, if you buy one and need a discount code, let me know.

3D movie software from www.3dtv.at
3D drivers for games at www.iz3d.com
Both work with loads of different output setups including dual projection

Let me know how you get on, i'm interested to see what others are doing.
critterfluffy (author)  lofty7 years ago
That is good information for the board.  Right now for the filters I am trying to just use the 3d glasses you get from the RealD theaters.  If you run light through the back side(eyeball side) of the lenses the light gets filtered and you get polar light(as far as I can tell).  These glasses are Circular Polarized and they seem to work perfectly as long as the filter is big enough to filter all the light.  I am trying to keep the build as cheap as possible assuming you have the projectors.  I will definitely be looking into that screen method and those drivers are going to be invaluable.  What have you been working on?
 I used the lenses from the RealD glasses but they are too small for my projectors so I have to put them really close and they start to melt and don't cover the whole image either.
The lenses in my projectors (sony px20) are pretty big so I'm going to get some proper stuff from polarization.com

Here's a link to my 3D cinema album on facebook with a few pictures of my setup. I've not made my final screen though, that was just experimenting with ideas.

Have you got Sky TV ? If you have give them a phone call and ask them to activate the 3D demo channel for you, some of the previews like the football look pretty good but it's a shame the live football and the world cup is restricted to pubs and clubs =( They don't launch the channel for homes until autumn apparently.
critterfluffy (author)  lofty7 years ago
Sucks that it was too small.  I saw that coming though.  For the image that you did get, was the light coming off of the screen polarized?  If so, then that means this will likely work. 

Right now I am trying to scrounge a projector but if I don't by payday(end of week) then I am going to just buy the parts and build one.  Don't want to wait any longer, you know.  Wont be ideal but should work just the same.

I was thinking of gutting a LCD panel for the polarizing filter but I think I might just buy a linear foot off of that web page.  Thanks for all the links. 

Looks like you have been working on or thinking about this type of thing for a while.  Have you done anything else?  As for SKY TV.  I live in Alaska, USA.  As far as I am aware, we don't have anything cool like 3d channels here.  We barely just got on-demand and HD channels about 1-2 years ago. 
 Yeah it works great, the reason it's not very big is it was only a test and I thought it be best to try different paints on a smaller scale so I didn't waste much if it didn't work
And yes, it was polarised very well. There are pictures in that album where I projected the words "LEFT" on one projector and "RIGHT" on the other and the opposite image was blocked out perfectly by the glasses.

Buy proper filters or you'll probably have ghosting issues. And unless you have the right tools and can find a bright/uniform back light and decent lenses, I'd recommend buying projectors. If the quality of the images is different in each eye, it will mess with your head.

Check eBay?
critterfluffy (author)  lofty7 years ago
been checking, I just don't have that much money for this sort of thing right now.  I will just have to save up to buy two of them.  I am thinking that it would be a good idea to get two identical ones or two with similar lumen output or else I would get the same "mess with your head result."  I also decided to buy filters off that page you linked as well.  They have some good circular polarized filters for $25.  I read that for this type of thing dont use linear since it can cause polarization filter issues unless the head is positioned just right.  Well, it is payday so I will probably have to check out ebay again to get atleast one projector to get this project started.
 Use linear, you get more ghosting with circular polarization.

If you tilt your head on the side even whilst wearing circular polarizing glasses, you won't really be able to see the 3D effect anyway because your eyes are perpendicular to the plane of seperation and that really will feel weird.

When you watch 3D films, you adjust your head without realising so your eyes are level with the plane of seperation so if you use linear and sit up right you shouldn't have any problems.

If you do it right and make a good quality screen, you shouldn't have a problem with ghosting so either would be fine.
critterfluffy (author)  lofty7 years ago

That makes sense about using linear polarized lenses.  The problem is that means I have to get glasses using linear polarized lenses.  The reald use circular.  I guess that just means I have to make sure I have enough left after making the projector filters.  Oh well.  Just a couple extra dollars once I get enough money to get the parts.  Projectors are expensive.

Just stumbled upon this thread because I was thinking about doing something similar. Have either of you had any luck thus far?

Trying to find some cheap solutions.
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