This is what i got so far. I'm not too sure how much thickness it is for the glass in front of the LCD screen.

That means the lines and the spacing are too small. You have to widen it out a bit:

Hi Cybereality what is your screen pbb ? and which pattern you are using ?

Its all explained in the tutorial:
viewtopic.php?p=55961#p55961

ppb is 15.987401568 so you used 11 lines at 16px and then 1 line at 15px ? last perfect pattern for you ?

Yes, that's correct.

ok
My screen ppb is 14.6891
so i tried 14.5 px but its to small and 15px is too big
then i tried 3 line with 15 and one with 14 = 14.75 still too big
so now what to do ?
can i use 4 line of 15px and 2 line of 14px ? 14.6666 very close

Well that would be the same as 2 lines at 15px and 1 line at 14px. If that doesn't work you can try 5x 15px and 3x 14px or something like that.

so can i use 2 lines at 15px and 1 line at 14px ? but its not even....you said that we have to use even number
just one paper left so i want to make a final print....

ya i tried 5x 15px and 3x 14p...its the best so far...almost half screen with blue and red color so i think just have to widen a little bit

Yeah, you're right. It has to be even in order to tile correctly. Forgot about that.

Sounds like you are getting close. Maybe 15 x4 + 14 x2 will work better for you.

i tried 15 x4 + 14 x2 but its not working...bit bigger...when i go back from screen then it turn white but cant see 3d but can see two different image from different points...i am so sad...what to do now ?

Well if you can see two different images, then it can be 3D. You just have to get the position correct so each eye sees a different image (one for left, one for right). Then if you play 3D content, like with the Stereoscopic Player or IZ3D driver, it will be in 3D. If the viewing distance seems wrong you can try flipping the sheet over (so the printed side faces the monitor), or adding a blank sheet in between.

Hey cybereality
Can I watch 3d movie with this setup ?

Hi! I'm french guy and I saw your video (Cybereality) on YouTube. I read the entire tutorial but I have some questions:

First:
My screen is an Asus VW220D 22" which has a dot pitch of 0.277mm so 0.0109055118 inches. My printer can do 1440dpi so my result is: 0.0109055118 X 1440 = 15.703936992

If I do a patterin of 16px X 1px, it's too big. I have read the part about interpolation, but I'm french and I don't really understand what I must do in order to have a better pattern.

Second:
In France, a piece of paper isn't = to 8.5 X 11 inches but 21cm X 29.7cm (so 8.26771651 X 11.6929133739 inches). Can I do a barrier with this size? Is that the result will not be distorted?

Thank you for your understanding!

@hlmasterchief93: You can watch 3D movies, as long as they can be played with the Stereoscopic Player. So NOT Blu-Ray 3D, but basically anything else.

@jon08: The interpolation means you sort of "fake" a higher resolution. In your case, 16 pixels is too much. So what you want to do is make something like 3 lines at 16 pixels and then 1 line at 15 pixels. So the pattern will look like

| 16px | 16px | 16px | 15px | ...

This will end up being close to 15.75 pixels, which is almost what you need. That actually might work, but you will probably have to tweak it further. But that should give you an idea.

Ok! But how to do 3 lines at 16px and then 1 line at 15px? Using the pattern, my whole layer is covered.

Do I need a pattern containing several black lines?


EDIT: I found this combinaison: 5 lines at 16px and then 2 lines at 15px = 15.71. It's ok?
EDIT 2: I found an other combinaison: 12 lines at 16px and then 5 lines at 15px = 15.705882352!! So a difference of 0,0019453609411! It's good or it's better to use small combinaison (because 12 lines + 5 lines, it's bigger than 3 lines + 1 line )

It won't exactly correspond to your display anyway. First because the pitch may not be exact, second because the glass between the pixels and the surface of the display is refracting the light and altering angles and distances. This depends on the refractive index of the glass and its thickness, and you should also consider the distance between your parallax barrier and the screen. The best solution is to try with something close to what you've measured and to modify the pattern untill it looks ok.



Ça ne correspondra de toute façon pas exactement à ton écran. D'une part parce que le pitch n'est pas forcément exact et d'autre part parce que le verre entre les pixels et la surface de l'écran réfracte la lumière et modifie les distances et les angles. Cette modification dépend de l'indice de réfraction du verre et de son épaisseur, mais tu dois aussi tenir compte de l'écartement de ta barrière par rapport à l'écran. Le mieux est d'essayer avec une valeur proche de celle que tu as calculée et de modifier le motif jusqu'à ce que ça rende bien.

The pattern needs to be an even number of lines, or it won't tile. Thats why I suggested 3 lines at 16px and 1 at 15px (making 4 lines total). You can experiment with different combinations, but they need to add up to an even number.

Ok. I tried to make a pattern of 12 lines at 16px and 5 lines at 15px but I have a problem. My pattern ends with black which creates a "loop". A picture says more than words:


Ok, I see. I'll try to find a better combinaison

Read my post above. The pattern needs to have an even number of lines (like 2, 4, 6, 8, etc.).

Yes, I saw yout post later ^^'

I think that 1,75 is the best that we can have (3*16px + 1*15px).

Only one way to find out...

I go to sleep and I'll try this tomorrow (it's 3:00 am here )

Im trying to make this for my phone, so no Stereoscopic Player

You would need to find software that could play 3D videos in vertical interleaved mode. I don't believe there is anything that does this for phones, you would have to create that yourself.

If you've got an iPhone you can simply buy the iGrilli3D, I don't know it this parallax barrier exists for other mobiles though. For videos you can at least use YouTube 3D which offers a row and column interleaved option. For downloaded videos you'd have to find an application which is able to interleave a side-by-side input or program it yourself as cyber said.

Ok! I have print the barrier this morning. Firstly, my printer doesn't recognize transparent paper So I then hacked by taping a white sheet on the back

And that works!!

So I did some test but the result isn't very good!

Firstly, with the alignement test we can see that my pattern is to big (15.75 but I need 15.70):




Secondly, I have test with some 3D movie and Stereoscopic Player. The result isn't good because I need to move my head too much from left to right (or from right to left), so I search a compromise but that result by ghosting.

What can I do?


EDIT: Can I do a pattern like this: 24*16px+10*15px = 15,7058823529411 (so close to 15,703936992) or a pattern of 34 lines is to big to be precise?

EDIT 2: Ok, I have print with 24*16px and 10*15px. The result with alignement test image show only one rainbow (orange to blue, it's a litte too big again)! I'll do a photo later. Now, I'll test with movies

Ok! This is a photo of the alignement test with my 24*16px and 10*15px pattern:

You should read this previous message by cybereality in this thread :
viewtopic.php?p=55961#p55961

He explains what to do with your pattern depending on what you see on the screen :


Although you're very close to the calculated value based on the dot pitch, your pattern is too big and must be made smaller. That's what I explained in my previous message, using the dot pitch only serves as a basis for a first approximation. You need to take into account the refraction of the light due to the glass, which has an incidence on the spacing/thickness of the black lines in the pattern.

You could calculate the needed spacing for the barrier, but for that you would need to know the thickness and refractive index of the glass (around 1.5 for glass, 1.000277 for air at STP), which are generally not made public. The best solution is to make several attempts with varying values until you find something acceptable.

All the math using the dot pitch is only getting you into the ballpark. You are really close now, you just have to experiment. As the guide shows, the barrier is too big right now. Start simple, doing a pattern with 34 lines is probably overkill (and will result in the banding you see in the photo).

I'd suggest starting with a pattern of 4*16px + 2*15px. And then tweaking it depending if its too big or small.

With this setup, the horizontal resolution with be 1/2 ? LCD 1920x1200 will become 960x1200 ?
If i need to make the convert program, i will look like that picture ?

You can use the Stereoscopic Player in column interlaced mode, or also the IZ3D driver to play games (vertical interlaced).

Thanks but as I've said, im trying to make it for phone
Will try and report later

Well the best thing to do would be do make some pictures using Photoshop (or GIMP) using layer masks with the interlaced pattern. That way you can at least start testing the parallax barrier right away. The images need to be the exact pixel dimensions of the phone, but you cannot be certain the photo app will not apply some sort of smoothing (that will ruin the effect). If you are developing your own program, you can get it to display an image pretty easy I guess. What platform is it you are targeting (iPhone, Android, etc.)?

I think that 4*16px + 2*15px will be too small. How tweak that?

Well try it and find out.

I'm quite interested in this method on a bit of a grand scale - 42inch to be exact.

I also thought perhaps anyone who has tried this can contribute their calculations and we can start building a DB - we could then write a simple program to generate a printable image for a given combination and make this easy for the masses

The problem with large sized screens (ie 42") is that there is usually a fixed distance from the monitor you need to be. This distance can vary, but is around 10-14", which can be too close for a big screen. But maybe with some ingenuity it could be done.

Ah I see - I'll probably only do this with my PC monitor then - perhaps lenticular may be something to investigate for my TV.

Cyber, have you given any more thought to trying your barrier method on a 5-7 inch display for a HMD? If it works it would out perform the PR4 by magnitudes. Can you get your barrier setup and test with a fresnal lens or even 2 in layers to see how it effects the view distance? If the Fresnel allow closer viewing distance without braking the 3d view it should be a go.
Then you could make a sheet for a cheap ebay 7 inch 800x480, if it works you could use a higher res screen like in Palmers PR4.
Cheers.