i was looking at the Microsoft Surface and was wondering where the LED’s were placed on the acrylic if there are any at all ??

they are illuminating the screen from underneath, not through the screen/ftir

to echo nima, they are indeed not using ftir, but more like 1 big IR illuminator, that probably exsists out of numerous IR leds beaming on the back of the surface

do you think they are shining the LED’s directly onto the surface? For my rear-illuminated reactivision table, i have the problem of LED hotspot feedback into the camera reflecting off the surface of the acrylic, so the LED’s are pointed slightly away from the screen.

(i think MS surface is using a specially-engineered glass to diffuse the IR light directly on the surface, they have the $ and resources for high-grade optics)

yes i think that as well

or you could put the diffuser on the bottom.

Putting the diffuser at the bottom will make the pattern recognition harder to detect because the patterns become very faint and blurry, at least that’s my experience with building my reactivision tables.

Since andy wilson’s previous multi-touch systems used exotic-glass materials, i suspect they sourced a very nifty screen. they are featuring the surface table at siggraph too bad i’m not going this year :(

then use a thicker diffuser and don’t use a piece of acrylic. Or use a very thin piece of acrylic. There’s no such thing as reflection free glass.

the reason reason is because i do not like the acrylic in a frame i like it to be the entire surface it just looks cleaner

u got a point there

ok for what i want to do i need to use the reflection method i believe wiki http://nuigroup.com/wiki/Multitouch_Technologies

if you want to do rear-IR illumination, you open up more possibilities for screen-diffuser selection since you’re not constrained to ftir.

you can simply use acrylic with mylar or you can get frosted acrylic, glass, or spray a coating on glass/acrylic too (like fake snow).... or even fabric!

im building two rear-illuminating tables (using reactivision) for object recognition.  I find that ftir gives much brighter blogs for finger tracking though.

set - 08 June 2007 05:51 PM

ok for what i want to do i need to use the reflection method i believe wiki http://nuigroup.com/wiki/Multitouch_Technologies

I’ve changed that wiki entry, we are calling it “Diffused Illumination” now.  Whitenoise has been experimenting with it recently http://www.whitenoiseaudio.com/blog/