Interactive Multitouch Display

Step 10: Software and demos

The key thing to making this all work is really the software that converts the detected blobs of light where your fingers are into awesomeness...of course a good soundtrack also makes a huge difference. I used touchlib which basically just worked out of the box. There is a calibration utility which saves results to a configuration file that is shared among the other apps. I also downloaded some Flash apps, including the light-box shown in the video. These interface with touchlib via OSC, a neat protocol for relaying timestamped events which should provide a good starting point for building your own apps.

Comments

[redinc]

Is there a maximum number of fingers that can be used on a multi touch screen?

[squiggy2]

no there is no limit to the amount of fingers you can use with a FTIR screen. the limits are

1. how many fingers you have - the average is 10

2. how many your computer can handle - the smoke demo especially uses a lot of processing power and the more fingers the computer needs to track and create effects for, the harder it will be.

[vlezcano]

Sorry, but the amount of finger cant be average as 10, because that means, more or less, that for everyone that have a missing finger, there must be one with 11 fingers, and if someone have missed 3 fingers, you will have someone with 13 fingers. the stabdar number of fingers is 10, but is not the average

[copiesofcopies]

It's true, 10 is the mode, but it was still a pretty funny response.

[squiggy2]

k fine my bad.
**'how many fingers you have - your average joe will have 10'
cheers copiesofcopies :)

[Apollo2543]

Well... Since a much larger number of people tend to have 10 fingers that would bring the average up. No need for someone with 11 fingers. If you have 20 people with 10 fingers and 1 person with 9, the average is 9.95 fingers. Close enough to 10 in my opinion.

[90mp11]

well, technically modally everyone has 10 digits, but only 8 fingers. Two Thumbs are quite common I hear...

[jadronx]

i thought everyone had 20 digits.....just sayin

[zeeebus]

Awesome Job!  This may be an idiotic question, but....I want to use my table mostly as a whiteboard for writing and brainstorming--hopefully converting into typed text too, if possible.  Would the side palm of my hand resting on the screen while I write interfere with the writing recognition?

[Hossein]

Dear Zeeebus
i know what i wanted to ask is out of line but believe me i wouldn't ask if this was not my last chance .
I really really need to have the PDF version of this multi-touch screen here coz i took it as my major project and i have to build it in a week time and to be honest i don't have the money to be a pro member and since i'm a student i don't have any visa card as well.
I was wondering to ask if possible can you downloaded it for me and send it to my mail i would mean a lot to me .
THANK you so much
[e-mail]

[squiggy2]

your hand resting on the side of the screed would create IR light that the wii remote would see, and yes this would mess up writing recognition software, but you could put a clause in the software that ignores any blobs bigger than a certain size - for a palm is much bigger than a finger, or any blobs that are stationary (to a certain degree) or something like that, which would fix things up and make it possible.
let me know how you go! (or are going)

[BIGHAIRYDUDE]

i think so

[nicksdjohnson]

 With all the diffusers etc, is it still possible to make out objects placed on the screen? I'd really like to build an interactive screen that supports both detecting finger touches and trackmate tags (trackmate.media.mit.edu), but it seems like this design will have too much diffusion between the screen and the camera for that.

[m2father]

I have bought a usb picoprojector. I intend to build up my multi-touch display using this cheaper projector (~US$250) instead of my last failed projector.  

It can project upto 40" at 1 meter distance away. Thus, I believe I don't need to have a mirror as reflector

However, I wonder whether it is workable while its resolution is just only VGA resolution.

Any comment and suggestion ?
Thanks!

[squiggy2]

sorry for the late reply, you've probably already built your screen :P
as far as I understand, the resolution of the projector wouldn't have any effect. The program would work out all the things in the resolution of the wii remote infra-red camera (1024 x 768) and it will simply be projected in whatever resolution your projector can do. the blobs of light made by your fingers don't have a resolution.

[Hossein]

 Dear Author 
my Name is Hossein i'm 21 years old and i'm from Iran and i'm doing my degree in malaysia i transfer my life to here since 2006 
i've been fallowing your awesome job and i need to say WOW nice job  you got there.
dear Author i choice this topic for my major project and i've been reading some papers and in the end i need to develop it can i count on your help please.
it would be a  honer to pick a expert brain on my major project .
Contact :
[e-mail]
skype : hosseinkarimi7

most regards 
Hossein

[workingonsomethingdifferent]

can you use it to control your computer or something like a paint software maybe on windows or mac????

[turkey tek]

yeah. when i last looked there was some sort of interface to touchlib to drive the mouse cursor so you could potentially use any paint program...although that wouldn't let you exploit multiple fingers. there was also a simple paint program demo in touchlib

[Stomp]

Where to find the program you use in the movie to play with the pictures? And what program for playing with the water? Regards

[turkey tek]

both programs came out of the touchlib source tree "flashSrc" subdirectory which i grabbed from here:

svn checkout http://touchlib.googlecode.com/svn/trunk/ touchlib

and followed the tutorial instructions here:

http://www.multitouch.nl/?p=23

to run them in windows, I downloaded a demo version of adobe's flash ide although i think there should be a set of free command line tools that would also do the trick.

[zachninme]

Now the X Server (thats the thing in Linux that basically does all the screen stuff) has a multitouch thing, MPX, that should allow you to have multiple inputs.

[ksjlkdjlddj]

Cool! Maybe you can figure out a way to make the screen sit in a more typical touchscreen case, and place the projector behind the screen. Now when you demo it to some random guy, "look i can touch!", thinks it is ordinary touchscreen, "let's put two fingers!", ha ha.