Instructables

Step 7: Modify webcam

In order to image the infrared light, we need an infrared camera. Fortunately CCDs in cheap consumer cameras are quite sensitive to IR, so sensitive in fact that it is necessary to filter out the ir in order to get good pictures. I got lucky and had an old intel web cam lying aroud in which the ir filter was a cinch to remove. Replace the ir filter with a visible light filter (so the camera doesn't see the projected display). I used the exposed end of a negative. See e.g., this instructable for more details.
 
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cool13q4 years ago
 could i use a wii mote as the IR cam?
crook175 years ago
Would it be possible to use a ir pen (an old pen with a ir LED and a battery inside) instead of using the large amount of LEDs
yeah man, take a look at what Johnny Lee has done. Obviously this would defeat the whole "touch" part of the surface though....
Johnny Lee vids @ http://www.youtube.com/watch?v=5s5EvhHy7eQ
MarkFW5 years ago
 Hi, 

I've been looking at these types of projects to create one of my own. Is there any software/modification of the idea here that would allow me to have a surface the same as this one, that just acts as a keyboard, and as such just projects the keyboard. Its for my new pc desk i will be building, and the idea is to create a square area solely for keyboard input, but allow the computer to use the input just the same way as typing a key on the board.

Any ideas would be great as this is stumping me, consequently stopping my pc station being created.

Cheers 
step 7 helped me out a lot!!! thx for the life (or grade) saving guide! =)
redex7776 years ago
Greetings and thanks for this wonderful project! Just one question/concern: Judging from your video, the "Pictures" application especially, it seems to lose sensitivity as you put your fingers towards the center of the screen. Could this be because the acrylic pane was too large, and the infrared light wasn't able to reach the center as brightly? ...or maybe the light was too diffuse and therefore inaccurate towards the center? ...or maybe im just imagining things, ;-)
turkey tek (author)  redex7776 years ago
Hmmm. I didn't notice that effect myself but it could be the case. A problem I did encounter with the middle of the screen is that there is a reflection of the bright lense of the projector off the back of the acrylic which the camera sees. You can get rid of this by subtracting an image of it from your input but if your fingers cross over the bright spot the tracker can get lost.
Smidge2046 years ago
Thanks for the great project! I'm currently working on my own 36"x48" countertop to use as an interactive drafting table (AutoCAD and custom IR-LED pen) I have a question about the webcam - I have a cheap one that was easy to convert and so far works okay for this (I got the stylus sorta-working on my LCD monitor by having the cam on a tripod behind me). Doing the math, though, my camera doesn't have the view angle to see the entire 36"x48" surface without being almost 8 feet away! Did you encounter any issues like this? If not, I'd love to know what brand of webcam you used or if you have any other suggestions. My current "all-else-fails" plan is to buy a $5 "fish-eye" (160 deg) door peephole and deal with the distortion in software. A new camera is a less kludge-y solution so if it's not too expensive I'd rather go that route. Thanks again!