Date: Sun, 9 Dec 2001 11:01:57 +0100 (CET) From: Søren Schmidt <sos@freebsd.dk> To: Danny Dulai <danny@ishiboo.com> Cc: multimedia@FreeBSD.ORG Subject: Re: Motion detection software? Message-ID: <200112091001.fB9A1wF25036@freebsd.dk> In-Reply-To: <Liam.1007847504.837241.1119.1345644620@SKODA>
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It seems Danny Dulai wrote: > >Well, I've done several intrusion systems that use very simple > >methods to detect motion/changes in pictures, it essentially > >just does this: > > > > for (i=0; i<sizeof(pic); i++) > > sum += square(pic1[i] - pic2[i]); > > if (sum > TRIGGER) > > return MOTION; > > else > > return 0; > > > >The two pictures are raw 320x240 8bit/pixel B/W in this case. > >The TRIGGER value can in this case be around 200000, it has to be > >low enough to see the changes, and big enough that bitnoise > >doesn't trigger it wrongly. Adjusting it is pretty easy, and it > >even allows you to not trigger motion on small objects like > >brids etc, but do trigger when something bigger happens. > > You can avoid noise by doing gradient based edge detection first and > then subtracting.. that's exactly what I did in my program for video4linux. Sure, but it all consumes CPU, the simple solution I depicted above runs on old 486/33 machines with B/W parallel quickcams and has CPU to spare for other things as well. -Søren To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-multimedia" in the body of the message
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