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Thursday, June 19, 2008

Infra Red Web Cam 1st test

In a future post I will show how to take apart the Creative Web Cam Instant. Incidentally, creative is currently selling these for $7.99 US click here or here to see what I'm talking about. The second of the two I believe has better resolution.
So, what I'm showing here is the difference in the thickness of the visible light filter versus the clarity you get. Please note, I messed up the lens taking it out the first time. So if you do this, please have a file handy and file the lens out of its holder.
This First image is the camera using 1 square of unexposed film negative. This is the best I can get the camera - so now you can see why you should take better care extracting your lens.

The second shot down is me using 2 squares of unexposed film negative. You can see it's gotten blurrier. I believe part of the reason for this is because it takes time for the squares to settle on to each other. I did this in succession to get the shots as fast as I could. So, basically the negatives don't sit well, and the air between them acts to refract and reflect the light a bit causing this distortion when it finally hits the ccd chip. Also, remember the lens is messed up!

O.K. so in this shot I'm using 3 slivers of film negative. I've tried to keep my face at the same angle so the comparison is easier. All these shots were taken at the same time of day and in the same amount of light. So, ceteris paribus the only variable here is the thickness of the filter.

I guess even the reason that 1 sliver works better than 3 is that 1 sliver is actually closer in thickness to the filter that originally came with the camera. Thanks to codongolevat for suggesting this idea. There are tons of great ideas and comments @ instructables - so please check this site out when you have the time. No one I have shown it to has regretted it yet! Also, there are people who have already successfully built, tested, set up, and filmed their touch tables working.

I said the next post would be about disassembling the camera but I might forget. I will try to do my best though.

Mac Book Pro Web Cam

This might be trivial but I thought I would post it anyhow. The webcam that comes standard with the Mac Book Pro is capable of picking up Infra Red LED's.
I'm posting a few pictures here of the remote control that came with my MBP as proof.

Tuesday, June 17, 2008

Smoke Demo Take 2

This is Juan and me trying to figure out why Smoke is crashing.

Smoke Demo

This is Juan and I working out the smoke demo.

Software Testing

So, my friend Juan and I decided to test the touch lib software on my MBP. I had to boot into XP b/c I couldn't exactly figure out how to setup the software and binaries in Leopard.We set up the modified infra red cam to view the lcd and then ran the software. Since the software detects IR blobs we decided to use a loose IR LED. We also used a remote control ( which caused some problems as I'll explain later) because we thought we had blown the led since we just connected it to a battery without a resistor. So, below I have posted some video of the test run. We successfully ran the software and turned the LCD screen into a "touch screen". We were able to maintain some level of interaction with the computer via the software. The software crashed repeatedly and I'm assuming that's because we used the LED from a remote control. Since remote controls tell the IR LED's to beep a sort of binary morse code (light off =0, light on =1) we tried to use a button that had the least morse code. So we did set the IR points with the remote and therefore ran into a few problems. When we ran the setup the rectangles would be irregular and choppy. Also, when we ran the smoke demo the demo crashed. Most likely the morse code overloaded the software recognition and crashed it. We tried using the IRLED and had slightly better results, but at the end of the day we don't have the wave guide (acrylic) and thus don't really have the physics backing us to make it smooth yet. However, we don't think it was bad for a ghetto rigged run!

Thursday, June 12, 2008

Multi Touch Interface through Frustrated Total Internal Reflection

This is my first article. I've recently found out about Jeff Hans paper "Han, J. Y. 2005.'Low-Cost Multi-Touch Sensing through Frustrated Total Internal Reflection. In Proceedings of the 18th Annual ACM Symposium on User Interface Software and Technology' ".

So what I'm trying to do is follow in the footsteps of the few that have already built their mock-ups and posted them up on

 I'll be guiding off of Han's paper and the instructable guides and posting the results here.

So far I've modded my old Creative pro web cam so that it now detects infrared light. I am currently trying to get a projector and deciding what bandwidth IR LED's to purchase.