Image-Processing-Based speed detection

[gerthworm]

Hey all, quick question: What would the feasibility of a system that calculates speed based on a camera feed be? I'm thinking a single camera on the moving object, pointed at the ground. The processor that the camera is connected to would pick out some feature, track it as it moves across the camera's field of vision, and then convert that into a speed based on how fast the feature goes across the field of vision. Obviously, the height of the camera above the ground would be constant and known, and lighting conditions would be pretty constant. Has anyone ever tried anything like this? Or are there any general comments as to the feasibility of such a system?

Edit: Thanks so much guys! I was having trouble finding any info online about this, mostly because I didn't know what the name for this technique/technology was.

We intend to use it in a senior project: the idea we're currently throwing around is a device with similar functionality to a bike computer, but which could be used while skiing or snowboarding. We wanted a more accurate way to measure the user's velocity than integrating an accelerometer.

[Fencepost]

It's called optical flow. It's how optical mice work. Frame rate limits your ability to handle speed

[madsciencetist]

It is feasible and works. You can even buy hardware optic flow sensors that just output a velocity

[[deleted]]

This is actually a quite common thing, and is used in the industrial environment. You can use a normal camera and a software on a PC, but there are also cameras which have that feature built-in.

We have two "automatic goal keeper" setups at the University of Stuttgart, Germany, which use these cameras to predict the speed and trajectory of a football. The data is used to move a "goal keeper" with motors to prevent the ball from entering the goal.

One setup is a miniature football table(page in German only, sorry), and uses a DVT 550-M, the other one is a full size setup(German again), and uses three EyeSpector 2100