Sorry to hear (read) about CRTs not working.


Nevertheless I got an Idea:
What if you make the barriers wider than the free spaces between them?
- you should get even less (wrong) light, so darker
- the wide barriers should eliminate ALL wrong light, even if they are placed slightly wrong. --> less ghosting!
- it should be (a little) easier to adjust the screen...


@ printing: I just copied a bmp file into word and printed it aproximatly the size I wanted it to be. Precision was not important, because of adjustment of screen... but it seems exactly that makes it hard or even impossible.

I have limited success with my barrier. It seems like the first tried when i simply changed the percentage in the pagesetup/printerdriver gives best results for me so far. I have a slight luck that the 600dpi of my printer in some way matches the screen quite good (not perfect). I can get stereodept and actually very good effect but with a maximum width of appr 7 centimeters before the lines doesn't match any longer. Then i tried to make an insanely big paralax barrier in paint shop pro. I took the ordinary 1000x800 and made it appr 9 times bigger. Of course the lines in the picture were smothed out but i could fix that by increase the contrast to 100%. Then i could regulate the barrier widht very easy by changing the brightness. But: When i tried to print it out with 10% driver page setup setting the driver itself filtered that big picture so the black lines werent totally black and the space between them werent totally transparent. :/ Had to trim the barrier right again but this gave a very bad experience. My conclusion is that a (quite much) better laserprinter is needed for making barriers that suits one pixel widths.
I might give 2 pixel wide barrier a shot but is very short on time. I do think this will work really ok though.

cheers

you can try to print each barrier a little wider and reduce the distance between the lines. It would need less acuracy of the printer.
You would only have to make shure there are as many lines as Pixels on a part of the screen.

like 3 pixels black and 2 white, then 3 black again... If this picture is zoomed at the right size afterwards it could help...

Those last shots I posted were at 1200dpi with a 6"x6" print (7200px sq). I am trying to get a 2px barrier working 100% before trying 1px. I think 2px would also eliminate any issues with sub-pixels or other sub-mm inaccuracies. At 1200dpi a 2px line takes up about 40 dots (or 40 digital pixels to 2 actual-pixels). However this is still not close enough. I have narrowed it down to somewhere between 39-41px per barrier @ 1200dpi. But that is not small enough. So the bare-minimum is probably 2400dpi to get a 2px barrier, for 1 pixel it may have to be even higher. These tests are on inkjet, maybe laser would provide better results. But 300/600dpi is not accurate enough for the parallax barrier.

Also, you will need a profressional editing program most likely. I'm using Photoshop, but GIMP would probably work as well. You need to be working at actual print size and not use any scaling when printing. Also make sure you go to the printer settings, set it for "black" ink and also make sure to select "transparency film" under the paper options.

Everything done as above. lol. And as i said: The first attemt works good because the screenpixel alignment almost matches the one in the printer (or times 2 or 3... you can calculate... lol). Tested photoshop but now it's confirmed that the printers "machineresolution" is 600 dpi. A dot cannot be placed between where the "locked" pixel place is. (forgive my bad english. se if you figure out what i mean). It'll be moved either to the right or the left depending on which is closest. Tested with photoshop cs3, pagesetup 100% and driversetting 100%. No change. . However: The subpixel issue is perfectly solved rotating the screen 90°. No more colorful rainbows but now i simply have greyish "optical interference" fields. Very much easier to align now though. I have it this way now and rotated it in the ati-driver. (Yes, ati9600 in this wonderful internet surfmachine ).

cheers

Ladies and gentlemen, it works!!!

I had to print probably 10 or 15 sheets before I got the alignment just right, but I was finally able to do it. The effect isn't all that great right now (only 120 barrier lines) but the method is sound. I taped some cardboard (about 1cm thick) to the screen to get the proper parallax. There is a very specific "sweet-spot" and I cannot really move my head at all, but when it aligned perfectly the images are properly shown to each eye. Look at the color test below (taken at actual eye distance):



Right now there is still some things that need work. For one, I am getting some pretty bad sub-pixel ghosting. I think turning the monitor 90° into portrait mode is a must. Its too late tonight to start getting into that, but maybe I can try tomorrow or something. Note that the parallax barrier above is set for 2 pixel spacing. If we want to use this with the SeeReal drivers we would need the 1 pixel barrier. But at least we know now it can be done. I'm very tired and I have a headache now from all the testing, so I must go. Enjoy the video:

http://www.youtube.com/watch?v=yu92wwR1b1g

Nice work there. How did you work out the scale? did you use ther printer scaling, or application?
I assume that you are using a laser printer for printing? I think I'll have to get som proper transparancy sheets and make one myself.

Wow cyber thats impressive. I wonder if we can con Iz3d into including a driver for us to home brew our screens

I am not using any scaling at all in the application. I'm letting the printer do it and it seems to work. Even though the old inkjet printer I have (hp deskjet 722c) is only 600dpi, I can get better results when printing at 2400dpi. Don't ask me how it works. I just kept printing different sheets and eyeballing the difference. You have to send it to the printer at the best quality, even if it doesn't support it. This may have to do with how Photoshop handles the printing, I'm not sure how that will work in other programs.

Anyway, here is the script I am using for the 2 pixel test barrier as shown in the above post (right-click, save-link-as):
[EDIT: I am no longer using a script, now I am using a Photoshop pattern. Keep reading...]

That is a script for PhotoshopCS3 (may work in CS2, not prior) and it generates the parallax barrier pattern. To load it up go in PS and click "File"->"Scripts"->"Browse...". The image is 6" x 6", but you can change this by altering the resolution. For the 2 pixel barrier I am using 79 horizontal dots per barrier at 2400dpi. This is on a 22" widescreen LCD monitor, depending on your printer and monitor that value may be slightly different. If you want to change the size of the printout, change the resolution in the source code listed below:



The first number is the 6" width times 2400dpi and ends up at 14400 dots. Second number is the height. Third refers to dpi, I am using 2400dpi.



For 2 pixel barrier I used 79 dots. For one pixel I imagine it would be around 40 dots. You can just edit the file in Notepad (or any text editor) and then reload the script in PhotoshopCS3. The lines will not match up if you place the film on the screen. It is made to be about 1cm off the screen for the proper parallax when viewed at ~2 feet away. Please note, you will need a lot of RAM to run that script. At the very least 2GB RAM with a good 4GB of scratch-disk for PS. If you are low on memory then your HDD may crash, so be warned. I had the scratch-disks set up the wrong at first and I saw the popup "You have 7MB left on drive C:", LOL! Be careful. I plan on fixing the script up, this is just the first version, but maybe it can be of some help.

I must have got confused with all the photoshop files I was working with. The working test (2 posts above) was done with a 3 pixel interlaced image. My mistake.

I just tried to do a 1 pixel barrier and it didn't work. It did print out, but it is not uniform. There is a doubled-up line about every 7mm. Before the jump the barriers work (for about 5 lines), but then it switches. So it looks like I will be having to buy a new printer to finish this project. If your printer supports 1200dpi+ then it may be possible, but 600dpi resolution is not enough. I also tried running the NV drivers in SeeReal mode with half horizontal resolution; it doesn't work. Technically it produces the correct output, but since the LCD uses the internal upscaling it ruins the clear-cut pixel seperation. It needs to run at native-res to work right. So there are still some technical issues to overcome, but I have confidence I can get it working with some more time.

I'm surprised nobody has mentioned this experiment from way back in 1999:

http://www.evl.uic.edu/todd/varrier/VarrierSPIE.html

They made a video wall version of it in 2005:

http://www.evl.uic.edu/core.php?mod=4&type=1&indi=275

They talk about fancy neural network driven face tracking using a visible light camera, but it seems to me that pairing this with TrackIR or Wiimote IR tracking would be a lot quicker. (And a lot easier to reproduce by the hobbyist.)

Without head tracking and the accompanying extensive software support, the method still works. It just requires viewers to sit still in the sweet spot, as people posting on this thread have already mentioned.

Anyway, the upshot of the first paper is their barrier. They got good results using lines that were 4 times the pixel spacing, and then rotating the barrier by 30 degrees from vertical. This line size might be a lot easier to deal with on typical home printers. The 3/4 opaque screen means you lose a lot of brightness and resolution, but it should at least work.

Note that the lines of images displayed using this method have to have a matching rotation and spacing, so the sample in this thread can't be used. The imagery has to be very closely tied to the barrier configuration.


Personally, I'm much more interested in experimenting with lenticular lenses, so thanks for the Lenstar link.

DM

Heres another project from 2002 that is interesting:
http://www.gametrailers.com/player/user ... 29806.html

They are using a moving parallax barrier to solve the "sweet-spot" problem, amazing stuff.

Don't ask me how they got it to sync up, I'm still trying to figure it out myself.

bump

What about building a 3D rig with these autostereoscopic 3D post cards? I found one and it kind of works. And somehow it is realy cheap! I think it works more with prism effect (voxels?) than with a real barrier...

Well maybe that is a good material to start with? If it just had the right 'size' for each line... maybe it works for some display e.g. from a mobile device. It is small enough and maybe 2 or 3 lines just do the job
I think I'll have to try it out somehow with more LCD displays...

I know that it's hard work and hard to adjust and the effect might ghost a lot, but who knows

It might work well. If the prismas are sort of 2-3 pixels wide there shouldn't be so much ghosting problem either. When converting from image you can have black barriers where both left and right data appears at the same time. That shoul decrease ghosting even more (light loss also of course).
Nice idea though.

Hi gyuys, i just found MTBS and this great DIY project,

i long since wantet to convert a (cheap) LCD Foto display to an parallax barrier S3D Display for my stereo pics.
i can contribute this link:
http://george.ph.utexas.edu/~schreck/schreck/cologram/
which descibes an DIY Autostereoscopic Parallax Barrier Display (no monitor invloved).

thanks for the link. It seems to be of good quality, but I don't have time to read it all now.
It seems like the author is capable of speaking German:
von [..] bis and so on

edit:
didn't we try with laser printers?


that explains why (at least I) haven't got anything. The other thing is of course, that I didn't even try to be precise

Suppose I would have 2 identical LCD displays, would it be possible to use the second display as a barrier ?
This would most probably give a good alignment (and one can change the barrier at any time, dunno whatfor, but hey

Just strip the second display, keeping the LCD, the front polarizer and driver electronics) and fix it onto the first LCD.
You will, ofcourse, need a videocard that has two outputs (the first will display the stereo image, the second will display the barrier)

I guess you could also create a perfect aligned barrier using light sensitive foil/film; fix the film on the display and expose the film with a .bmp with the disired pattern on screen
Haven't found this kind of film though, it should be sensitive to all three colors used in the LCD for sharp edges.

I think the second lcd would be ok over a small area in the centre but as the angle gets greater the further to the edge you go the barrier lines must be in different positions and of different width to show the stereo image correctly which would be out of the pixel range of an lcd. Using a barrier lcd of much higher res and pixel density would have more success i think.

Found this paper that also stacks two LCDs: www.evl.uic.edu/aej/papers/vr07.pdf . Nice stuff to read

They also use head trackers for multiple viewers (dynamic barrier generation, denpending on the positions of the viewers).
Alignment does not seem to be the problem, but barrier resolution is somewhat limited due to the color filter on the barrier LCD.

hey is anyone still working on this? it seems really interesting. think ill try a test.

I tried. It seems like my monitor dpi size as well as the laserprinter dpi size almost matches which gives me a "proper" effect. It only works for a few cm's before the pixels don't match any longer though. Not keen on getting another printer or increase the pixelsize so i gave up on it. It's absolutely possible but if you want autostereoscopy on pixelbase you're going to need a very good laserprinter. The foil i was using is foil for laserprinters and seems to keep the shape without problem (during printout the sheet passes through a heating drum in the laserprinter for hardening the toner purpose).
The sheets i used was "Corporate express: Overhead transparencies: A4: 608 83 29". This foil seemed to keep the shape through the laserprinter and gives no problems.

cheers

Do a google for lenticular screens. It seems there are many companies out there who sell lenticualr sheets of all shapes and sizes and custom jobs. Would be cool if you can find a matching one and just stick it over your lcd. Instant autostereo using interlaced driver.

problems:
- highly acurate barrier (plastic might stretch when heated up)
- acurate positioning
- color and positioning of subpixels (for LCD)
- blurryness of CRT (but they can be rezised well Unfortunatly they have a curved scren
- maybe a barrier for a very low resolution works. A 1280 LCD could be driven at 640 e.g.

I wish best luck

What's interesting about the RGBRGBRGB aspect of LCD monitors could actually be used to it's advantage I think. If using head tracking you can determine where the ray locations from each eye hit the screen, as well as the projected width of the vertical strip on the monitor, you could calculate all of the Red Green and Blue sub pixels that fall within that projection.

Then all you would have to do is create an array of groups of sub pixels for each eye, and map the color values to those sub pixels using linear interpolation.

So say for example you know the first pixel of the right eye is going to see a group like this:

|RGBRG|

You now have a rough equation for the color at that location: 2*R+B+2*G
Break that up into components and set it equal to the determined visible color at that location (probably the first color for the right eye)

2*Rscreen = Rimage or Rimage/2
etc..

Additional weighting of brightness values could be calculated as well, and the algorithm could be fairly well optimized because you only have to solve the weighting once for the columns then you can apply it to all the pixels in that column.

The color distorted output image should then look correct for each eye, and you've taken advantage of the higher horizontal resolution.

Any thoughts?

Very helpful lenticular info.

http://www-isl.kaist.ac.kr/Papers/IC/ic117.pdf

i realy enjoyed reading this thread:

And i might have an idea that I want to try:

I want to use this 7 Inch screen with a resolution of 800x480 pixel.
http://www.geekstuff4u.com/accessories/ ... splay.html

Here are some specs: Display size: 6" × 3.6" (15.25cm × 9.15cm) = 133.28 PPI with a side ratio of 4 : 2.4

I calculated that it has approx. 30 lpi.

Now I thougt about buying a lense with 30 lpi and putting it on the screen.
Could i use the iZ3D driver on Interlaced mode or the stereo photo maker on interlaced output to see some pictures?

Could it work?

Theoretically yes. Practically... let's see.
It's all about how well the lenticular lense matches the display. Please come back with results if you go for it. I'm curious.

does anybody know a small display with a small resolution of 320x240 with a sice of 7" or simillar? It might be a lot easier with a smaller resolution but same sice.

well I tried the 3Dee Shell from Spatial View:
http://www.spatialview.com/en/node/489

It turns my iphone into an autostereoscopic screen using a lenticular lens. It is pretty amazing actually. The 3d effect is impressive for this rather small device. I will post some pictures later and maybe a review of some kind.

greetings and keep working on the autostereoscopic screen, i dont see any movement here, keep it up guys!!!

So I have resurrected the parallax barrier project. I got a 1200dpi mono laser printer, the Samsung ML-1630 ( http://www.overclockersonline.net/?page ... s&num=1742 ) and a 50 pack of laser transparency film from Sparco. So far I have been getting good prints with the ML-1630, it is definitely more precise than that old 300dpi inkjet I was using last year when I started this. At 600dpi I was able to print a 5 pixel interlace pattern (5px black, 5 px blank, etc.) and it was nice and sharp with no bleeding or anything.

I did some math and I figured for a 22" 1680 x 1050 display the individual barrier lines should be around 6.7 pixels @ 600dpi. So I tried with a 6px line and also a 7px line @ 600dpi and the results were close but not there yet. It seems 600dpi wont cut it. Then I tried with a 13px / line @ 1200dpi and I am getting somewhere. I still have a lot to figure out, but I am at least in the ballpark here.

The image below is with the 13px barrier and on the screen is a 1px vertical interlace pattern of blue and red. If the parallax barrier worked perfectly then you would be seeing either total blue or total red on the screen. As you can see there are some strips where it does block out the intended pixels and you do see either red or blue. However it goes out of phase and the effect is lost. But I am getting somewhere, much closer than I got with that old inkjet.



Since I am at the maximum dpi my printer can handle I will need to figure out some techniques for increasing the precision. One method would be to keep the lines at one sizing (say 13px) but alter the spacing (to say 11px) to offset the phase. If that is not enough I may have to create a more complex pattern, where say every 10 lines it adds or removes some pixels to offset the pattern. Using a combination of these methods I think I can attain the proper 1:1 pixel mapping necessary. So far this has only been with 2 days of experimenting so I imagine I could have something working in a couple weeks maybe. Stay tuned.

Wouldnt it be easier and cheaper to take your image on disk to a print shop and get them to print onto your film with their higher quality printers? Should only cost a few bucks max.

Sure, but you might have to make 5 prints to find out about which resolution that suits best and then maybe 5 more to finetrim it. I don't think he bought the printer just to catch up on parallax barriers though.

Nice test cyber. What happens if you try to make a parallax barrier invertical direction instead? (you do have to tilt the monitor too. I had best "success" doing this).

Not really. I needed a new printer anyway and it was on sale for $90. Plus the transparency film is only like $10 for a 50 pack. And it is much easier for me to push a button and then 3 seconds later have something in my hands rather than burning a CD (15¢), taking a train to a copy shop ($5), waiting around for them to print it (time=$), paying their rip-off prices for each print ($$$), etc. Once I get the template finalized I will be sending it off to a professional printer so I can get a full-sized print that will fill the whole monitor. But I can't be going to the copy shop every time I need to make a sub-pixel adjustment.

Ok, so I have made some more progress. I am much closer than I even thought. You were right, Likay. I needed to turn the monitor into portrait mode. I already knew I was going to have to do this eventually, but I thought since I was only testing with primary colors (red/blue) that I could avoid the sub-pixel striping issues. Apparently not. So I am getting much better results in portrait mode. I also altered the pattern so it alternates between 13 px lines but every 6 lines it inserts 1 blank pixel. This is a lot closer to what I need, I am almost there:

Ok, so I have made some more progress. Right now I am using a base of 13 pixel wide barrier lines @ 1200 dpi but every 6th line is 14 px and then every 24th line is 15 px. This is extremely close to what I need but I am still off by some small fraction of a millimeter. This is giving me some ghosting and its losing the phase at the edge of the sheet. However it is like 80% there and I don't think it will be much longer until I have it working 100%. It is certainly working good enough as a proof of concept and I am sure at this point that the method is sound. I have recorded a short test video just to illustrate the effect. Its not perfect yet, but you should see it is very close. The video is uploading right now, will post in a minute.

Anyway, I was able to play about a half hour of Mirror's Edge using the parallax barrier and it does work, I was getting a nice 3D effect. That said, there was pretty significant ghosting and the viewing angle was painfully narrow. In fact, I wouldn't even call it a "viewing angle" it was more like a single point in space. Move outside the point and there was either a lot of ghosting or the eyes would swap. However within the "sweet spot" the stereo effect was legitimate and looked decent. There was also a graininess that the barrier added making the image quality somewhat muddy, but otherwise it was full color 3D. I won't be selling my Zalman any time soon, but all things considered this DIY mod came pretty close for what amounts to 25 cents worth of a transparency sheet. Stay tuned.

Lol that is awesome

Right now I am in spitting distance of having this thing working proper. It is already somewhat playable. I have fine-tuned the pattern a bit and I am now adjusting within the hundredth of a pixel. It won't be long before I find the right number. Tonight I was able to get rid of some of the ghosting from the last test. It may look the same, but if you watch the video closely you will see there is slightly less cross-talk.



I also attempted to take some stereo photos of the setup, but they didn't come out too good. I was just using my standard Canon PowerShot and offsetting the shots a bit. You can kind of get an idea, but it really doesn't capture how it looks in real life. For me to do this proper I will need that Fujifilm W1 and a tripod (neither of which I have at the moment). But this should be enough to at least prove I am not full of it.

Awesome work!