benbritten.com

Ok, So I am a mac guy. Not a zealot mind you, but I develop software for the mac, it is what i do for a living. But, why reinvent the wheel? there is a great library for machine vision stuff already available: touchlib. I suggest if you are doing any multitouch stuff, to start there. . Also, if you are a mac person, you should check out the Mac Touchlib Install Tutorial at nuigroup.

This is where i started. however, step one (download and install darwinports) was taking too long (i am very impatient :-) so i started writing my own blob detector. By the time i got to step 4 I already had a working (albeit very very poorly) blob detector using my crummy modified iSight as the input source. (note: i didn't really start from scratch. I had already done some firewire capture projects based around this excellent and easy to use framework: CocoaSequenceGrabber by Tim Omernick. So really all i did was take a quick background capture, subtract it from the source image, and then do a simple threshold to get my blobs, this took all of about 20 minutes. of course, that is the easy bit :-)

Anyhow, since I was already going down the path of doing it myself, i figured i might as well do it all the way, so I abandonded the touchlib and started my own Obj-C/Cocoa multi-touch project. (which i will post once it is in a form that I feel OK letting into the wild).

Here is a screengrab of a very very early version (let's call it 0.01 beta :-)

All it does right now is does some basic image processing to get the blobs in a nice findable state (ie monochrome, difference matte, threshold) then identifies them with a simple raster/recursive algorithm, and then build a blob event list based on how far they have moved, whether they are 'new' or whatever. (ie if they havent moved too far in one frame they are considered the same blob, otherwise they are new etc..)

I am currently working on a configuration program now that I have the basic blob detection working.