Video: It's really easy to use a Raspberry Pi to create a cheap surveillance system with just one camera, but things get complicated if you want multiple cameras. Over on Pyimagesearch, they figured out a way to get it done. The setup here uses USB webcams that hook into a motion detector script and then run through the Pi so you can monitor it all in real time. It's not a terribly complex project, but you'll still need some knowledge of the command line to get through it. If you've been wanting to run multiple cameras in a surveillance system on your Pi, this is one of the easier ways we've seen to do it.
Multiple cameras with the Raspberry Pi and OpenCV [pyimagesearch]