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According to some posts published on the nuigroup, if you want to illuminate the PMMA plate directly from the side, you have to use enlightened PMMA and also use some silicon rubber on top of it. This seems a bit complicated for a prototype… Also it appears that the silicon rubber tends to “blend” the LCD images …
So, it is now time to move to another technique: Laser-LP. This is basically the same process as the FTIR process apart from the fact that IR-lasers are used instead of IR-LEDs. Also PMMA is not needed anymore. Any transparent material will work as lasers beam is generated over it.

I ordered 4 lazers from aixiz along with 4 88 degree line lens about two weeks ago and receive them today. Now I need to build a suitable power supply for at least 2 lasers. More to come soon …

It’s been a while since I posted new stuff on Touchmyworld … Well, between my DIY Modular, iPhone programming, work and vacations, I didn’t have something new to show off. Until today.
I finally found a PMMA plate at Leroy Merlin for 20 euros: 500mm * 500mm * 80mm. As my LCD is much smaller (it’s a 17 inch) I had to cut it and, thanks to Philippe and his new Makita saw, it was really easy.
I now have a 390mm * 320mm * 8mm plate, enough to fit with my LCD display.
I also prepare the aluminum board that will hold the IR leds: 36 leds on the long edges and 28 leds on the smalll ones.

Aluminum boards that will hold the IR Leds

New step will be to mount the leds with the resistors and illuminate the PMMA plate so I can make some testing…

Here are some video of Philippe at work:

My Xbox Live Vision camera arrived today . I bought it on priceminister for 25 euros (port included) : good deal.

While it might not be the perfect webcam for MT, it’s ok for a prototype and at least, the camera is natively recognized on my MacBook Pro.

So, first thing was to remove the infra-red filter at the bottom of the lens so that infra red light will be visible. I follow instructions from this guide . Then I put some exposed negative film so that normal light will be filtered. It takes only a couple of minutes to do those modifications and now I’ve got a nice moded webcam to test for my MT.

Here are three videos that show how IR light is received. In the third one you will see a bottle of Coca-Cola that serves as a test to ensure eveything works correctly. (In fact IR light pass thru the Coca-Cola, meaning that you can see what is behind the bottle … magic ? no …).

 

 

 

More to come soon as I found a PMMA plate today at Leroy-Merlin (50mm*50mm*8mm for about 20 euros).

First of all, sorry for not posting so often on this blog but I’m also building a Modular synthesizer, so the Multi-Touch Table project has been put apart for the last weeks … until yesterday …

I get a broken LCD for free at the office and try to repair it. The LCD is an IBM ThinkVision 9494-HB0 and  its power supply was dead … I tried to replace it with one I’ve got from a synth project and … it worked !!! : this means that I have now an 18″ LCD to start making my MT.

The problem when using LCD based MT is that you never know if the LCD you choose as the FFC issue … until you disassemble it…

Here are some pictures of the process.This LCD was a breath to disassemble and does not have the FFC issue which is really great news !

There are numerous softwares that can detect blobs or fiducials from a camera but we believe that Touché is the way to go. We can tell if this is the best software out there but installation and calibration seems so much easier with it … and this one has been made on Mac for Macs …

Again, we did not tested it but the perspective that Touché framework can be embedded in Cocoa application just open the door for great OS X applications that could use Core Animation and Quartz Composer. Also we will be able to use Processing but not Flash (yet …).

We decided to go for an LCD based multi-touch FTIR system. The choice to go for an LCD was mainly decided to reduce cost (a projector  is quite expensive) but also to have a system that could fit into a small table (like the one you’ve got in your living room).
Kowning this, it’s now time to find all the parts we need to start our project. 

First, the camera: It will be an XBox Live Vision camera as it has proven to be quite efficient but mainly because it runs natively on Mac OS X. We found one on http://www.2xmoinscher.com/ for 32 euros (port included).

IR lens: we will use some exposed film negative. It’s cheap and seems to do the job quite well. That should be enough for our first prototype. The finished product might use some professional IR lens (ebay shop) but for the moment, we are trying to cut the cost down as much as possible.

LCD screen: 15″, 17″ should be a good start. Looking around the net, the cost is between 50 / 80 euros. The only drawback using an LCD based system is that you have to carrefully take off the different parts (not breaking the cable between LCD and electronic) but also the fact that some LCD screen have backlight that emit infrared light … If the one we found emit IR light then we will have to install some window film (see this thread on the nuigroup forum)

IR leds: We have not decided yet if we go for a DIY system (leds soldering etc etc) using those cheap one or go with this much more confortable solution…

Two blogs from DIYers that use the LCD technique :

• http://eleme.ntal.ws/
• http://multitouch.geomentary.com/

We have been really excited the past few days after watching the MTMINI video and decided to build one ourself.

After searching the web, reading blogs and watching amazing videos, we ended up on the NUI Group forum. You get everyting you need to build a multi-touch table for yourself whereas you’re a DIY beginner or a multi-touch interface guru …

In the next few months, we will describe our progress in making a multi-touch table based on the FTIR technique which will hopefully help new comers and enthusiast DIYers.

Fingers crossed …