Detecting an intruder and setting off an alarm

Let's dive right into the wonderful world of motion detection!

The basic idea of motion detection is pretty simple from a computer's point of view—the motion detection software processes a continuous stream of images and analyzes the positions of the pixels that make up the image. If a group of contiguous pixels above a certain threshold starts to change from one frame to the next, that must be something moving. The tricky part of motion detection is weeding out false positives triggered by naturally occurring changes in light and weather conditions. The steps to configure motion detection are as follows:

1. We'll be working with a motion detection application called Motion. Install it using the usual command:

   pi@raspberrypi ~ $ sudo apt-get install motion
   

   With Motion installed, the next step is to create a configuration file for our camera. The Motion installation puts a sample configuration file inside the /etc/motion directory...