In many applications, you want to detect an object but would also like a record of who or what it is. A camera is a perfect instrument to answer the who or what question. The challenge is how to trigger the camera at the right time to get the best image. Utilizing a 2D radar such as the OPS243-C from OmniPreSense, you can now have a very sensitive motion detector combined with a range finder to trigger the camera at the optimum moment.
The OPS243-C has a simple API which allows you to filter for particular speeds and ranges for an object. For example, you have a speeding problem on your neighborhood street. You want to capture an image of the vehicles who are exceeding the speed limit by 10 mph. You can set a speed filter at 35 mph with a couple simple commands (US and R>35). A camera will capture the vehicle and its license plate best when it's around 25 m away. For this, you set another filter for r>25 and r<45. Turn on the simple GPIO from the radar to act as a trigger to the camera with an IG command and you're all set. The camera will now capture pictures of the vehicle who exceeds the speed limit by 10 mph and is between 25-45 m from the camera.
Of course, this set up can be used to capture most anything. It could be an intruder stepping onto your property or an animal approaching your chicken coop. You can replace the camera to set up some type of feedback such as a turning on a bright light or loud audio. And for those trick or treaters approaching at Halloween, maybe a nice scary sound or flashing of a strobe light will do.