We are a student group at Daniel Webster College in New Hampshire.
We’ve been trying to build our DI box for a while now but as we are getting close to the end of the semester, the pressure is getting higher.

Our main problem is getting the IR light to diffuse evenly (coming from our huge 140 LEDs IR-Illuminator).
I’ve looked in the forums and it seems others are also having the same kind of problems:

http://nuigroup.com/forums/viewthread/1122/

so I am going to just ask the people I know have succeeded, how they have approached this.

Our setup is basically:
-Microsoft webcam with 3 layers of exposed-developed films
-we use Lee Filter, 225 Natural Density Frost for our projection surface
-SHORT RANGE IR illuminator 140 LED
-we tried putting aluminum foil around our box to help diffuse the light

Now Onto the Questions, first to WhiteNoiz:

based on this thread
http://nuigroup.com/forums/viewthread/1503/

and the video
http://www.youtube.com/watch?v=DMVrcW5HKG0

Could you post some pictures of the interior of your new box (or just talk a bit more about it)?
Also I remember you also used the same huge IR-Illuminator as we have (In fact I think I bought it because of your setup).
http://www.flickr.com/photos/whitenoiseaudio/840168722/
What is the diffuser that you are using in that picture?

Now a question to Fairlane:

From your photo gallery it seems you are also using the same IR-Illuminator:
http://orionmultitouch.atwebpages.com/

How did you solve the problem? some insight would really be appreciated it.

clueless - 26 March 2008 03:58 PM

Now a question to Fairlane:

From your photo gallery it seems you are also using the same IR-Illuminator:
http://orionmultitouch.atwebpages.com/

How did you solve the problem? some insight would really be appreciated it.

Hey Clueless, I’m at work at the moment and I don’t have any photos on hand right now, but I’ve drawn up a crappy picture in MS Paint to show the layout of the illuminators. (I had to make another 2! 1x 80 IR Leds and a smaller 45 Led illuminator too!  )

Illuminator number 1 is the 140 IR led from my website. Number 2 is the 80 IR Led I made up, and Number 3 is the 45 Led one.
The purple border represents the physical screen projection size in relation to the illuminators and the box.

The need for more IR light was due to the fact that during the day or close to a IR light source (overhead lights or the sun) the IR that I was generating was not enough to receive clear blobs.

For me, I’m very happy with the result of the 3 illuminators I’m using in my DI setup now. When I get home tonight I’ll take more pics of the inside of the box/illuminators for you.

Ok, so below are some inside shots of the DI setup I’m currently working on. It’s still a work in progress so the box is pretty ordinary. Also my piece of frosted glass is taking a long time to be delivered :( so I’m using a piece of ordinary glass with baking paper as a diffuser. The camera (which cannot be seen from the photos) is mounted on the tiny mirror that the projector is pointing to (also out of shot) and faces the larger mirror. This means the entire screen can be seen without mounting the camera too far away.

Virtual DJ ftw!

HyPe! - 27 March 2008 08:46 AM

Virtual DJ ftw!

Definitely!

How are you powering your speaker?

cerupcat - 27 March 2008 03:59 PM

How are you powering your speaker?

At the moment it’s just there for looks. I haven’t wired the sound section yet. I will be using a slim-line home amplifier to power 2 speakers and possibly a subwoofer. The speakers will probably be wired this weekend.

Just using headphones when playing with Virtual DJ, at least I’ll look the part

Heh, so where would the sub and amp be? I wouldn’t recommend putting the sub into the box especially since yours is smaller. I have 2 8” speakers on mine. If you get below 100hz you’ll definitely vibrate the screen with a smaller box like yours.

cerupcat - 27 March 2008 04:30 PM

Heh, so where would the sub and amp be? I wouldn’t recommend putting the sub into the box especially since yours is smaller. I have 2 8” speakers on mine. If you get below 100hz you’ll definitely vibrate the screen with a smaller box like yours.

Good point, maybe i’ll just stick to the speakers. The amp is about 2 inches deep and about 14 inches long so if you look at picture 2 of the shots above, it sits nicely on the left side standing upright. I’ll post more pics soon and you’ll be able to see what I’m talking about.

I might change to the Showcase section so I don’t hijack this thread

Hey Fairlane
Thanks for the pictures and the respond, that does clear things up a lot.
So I guess the take-away is (if you’re starting out) don’t buy one huge IR illuminator.
Also I would love to know how good your frosted glass works out (when they do come).

No probs,

I certainly found that one giant illuminator and a short distance to project the IR light doesn’t cover the whole screen properly.
(And that’s testing the illuminator with all kinds of angles, using mirros, diffusers etc.)

Having said that, David’s photos on flickr clearly show only one IR illuminator (possibly 140 LED).

http://www.flickr.com/photos/whitenoiseaudio/

I guess for me it was trial and error, cause I wanted it to sort of work in the daylight too. It also depends on the spread of the LED’s. With my 140 IR array, I could light up a DI screen 80 meters away the beam was that narrow!

Keep us posted on how you go with your setup, and we’ll try and help.

Do you need that many LED’s because you are using glass, which I’ve heard sucks up a lot of IR?  We were thinking 50 LED’s onto plexi would work.  We want it to work in daylight so will use Rosco to cut out the ambient from outside.  Should I order more LED’s?

I think it is the wrong illuminator for my setup most probably… Personally, I have found that using glass does let a lot more IR light out requiring a brighter illumination, however many people on this forum have had great results with less illumination than me. I think camera sensitivity/illumination/filters/environment are the key factors and with right amount of each the display should work well. Hold off on ordering more LED’s unitl you test your setup. You may find that you don’t need much to get the effect you want.

well, we finally built our table, and in the end the extra IR Illums were the solution (plus an actuall IR filter).
It’s not perfect yet (as you will see most of the stuff has to be outside the box for it ro sun smoothly) but a little bit more adjustment should fix that.

Here are some pictures and a video we took this week.
Thanks again for all the pointers.

Hey clueless, nice vid! Looks really smooth and responsive. Can’t wait to see more

thanks.

I just looked at one of your youtube vids:
http://www.youtube.com/watch?v=hWOj5E7o68c

and was wondering how you got your multitouch so responsive?
Our’s is okay but is no where as fast as your’s (you can see in our video that the blobs lag behid the finger movements).
Is it a high framerate camera (our camera is a microsoft lifecam 30fps), or maybe just a fast computer? other than those two I’m not sure what else could cause the lags.