HARDware

These are some notes of stuff I shouldn't leave out of my presentation of the multi-touch water project:

note 1. The wooden frame was the hardest part and I didn't took a picture of it because I was FED-UP with it.

note 2. Thanks list:
> Ikbal [IR LED lights]
> Andy Buckland  [helped me with the LED ribbon]
> Shane [how to stick very thin acrylic pieces together]
> Alex Hulse [how to create a wooden picture frame]
> Alan Gardner [helped me with the wooden picture frame]
> Varun [hosting my installation]
> Suki [help with the cloth to keep the inner of the installation dark]
> Rave's IT department for a floppy!

It was my christmas present from them to me! =) After 1 day of searching and asking, receiving answers like "There isn't any floppy left in Rave or anyway order it from e-bay.." I finally made it. Someone suggested me to ask in the IT dept. and so I did,. and one of the IT guys there had a box of floppies on his desk !!! I mean, he uses them in daily basis? that was a moment for happiness for me. But all the people there.. it felt like home to me; computers' people.

note 3. Cost:
> Burned my finger, cut a piece of hair because of glue, cried (for the wooden frame..).

note 4. What to improve in the next project:
> time management, though I think I couldn't have done better for this project in this period of time.
> "Taking risks" and "not being afraid to fail" requires very strong nerves.
> Avoid wooden constructions.
> Take into consideration "Opening Hours" of departments I'm planning to use.

Multi-Touch Water

Last week I explained my concept to Martin and somehow with his hints and some work this project turned to be much more interesting than it looked like from my research on multi-touch screens. The concept will be as explained in the previous post with only difference that for screen instead of acrylic we will use water. I've been working on various stuff since then and finally my steps will be:

[MAX/Jitter]

 1   Build software that recognizes blobs.

 2   Build software that projects a video composition which responds to the user's blobs.

[Hardware]

 3  Build the sink with the IR lights (Many thanks to Ikbal for them!)

 4  Modify the PS3 Eye camera to read only IR light.

 5  Add the semi-transparent projection foil and the projector.

 6  Calibrate so the projection fits the user's input.

I'm currently at number 2. If it wasn't for a Quicktime Update (?!) I would probably be much further than that.

Now, firstly I'll try to make a simple functional software so I can go on with the construction and when I am done with it I'll return to enhance the projection software.

Multi-Touch Screens Research

The technology I chose to explore in the next project is the multi-touch screens, screens that recognize two or more "clicks" at the same time. Weird as it might sound, it is much more cheaper to build your own multi-touch screen rather than to buy one, since that would cost a few thousands. In my research I found that there is a whole community of DIY multi-touch screens' enthusiasts (http://nuigroup.com) who since 2006 have build a great content with tons of information, "How-To"s and tutorials. That made me thinking "So what if I decided to do so?"

Technologies
The disposable Multi-Touch technologies by now are explained and compared here. I spent some time looking after which table would be the best (robust and easy to build) to try implementing. I ended up with the FTIR (Frustrated Total Internal Reflection) technology which is also one of the most popular in this community.

FTIR
The multi-touch screen with the FTIR technology works this way (quoting from here):
 "Infrared light is shined into the side of an acrylic panel (most often by shinning IR LEDs on the sides of the acrylic). The light is trapped inside the acrylic by internal reflection. When a finger touches the acrylic surface this light is “frustrated” causing the light to scatter downwards where it is picked up by an infrared camera."

Click to enlarge

So the camera that captures only IR light, when we touch the FTIR screen shows something like that:

Straight-forward and easily understandable.

The Screen
There are 2 ways to place the IR LEDs to light the acrylic. Either with soldering and wiring about 100 LEDs or by using a LED Ribbon. There is a very big difference in the cost between them but the cheaper one takes ages and requires familiarity with electronic stuff. I haven't make up my mind which one is the most efficient yet.

The Surface
Now is a whole lot of story, to create a surface that would push the acrylic only where our finger is (it won't stay pressed, and it would be very sensitive for cases of dragging etc). Thankfully, everything has already been done! So the surface of the table is constructed by the following materials in this order (click to enlarge):

Rear-projecion foil and Infrared blocking foil.. hm I'm not surprised that I don't understand what should I put there. But according to my research the best combination, should be something like:

1. Polyester drafting film, 
2. Vellum, 
3. Silicone & Zylol with this technique, 
4. 3/8th clear Acrylic

The cabinet
In the FTIR table, the IR light is captured by the IR camera and the projection is done with a front-side mirror, since the short-throw projectors are much more expensive. So the placement diagram is something like that (click to enlarge):

IR Capturing

Projection

The List
If we were to make a short list of what is needed we would have:

1. LED Ribbon (or soldered and wired LEDs)
2. Polyester drafting film, Vellum, Silicone & Zylol, clear Acrylic
3. IR Camera (PS3 Eye), floppy disk
4. PC: Core 2 Duo and 2 GB of memory
5. Short-throw projector (or home-theatre projector and a font-side mirror),  heat-absorbing glass
6. (Wooden) Cabinet

Software
Thankfully, there's lots of free and good software for multi-touch tables available in the web.