Walk or run? Whatever you do, the computer knows...

Good news. I had managed to sort out some problems in my project. The key problems was how to extract data from the sequence of video taken. There are many different approaches had been done and I had chosen a method based on cyclic motion as shown in a paper published in IEEE journal.

You can imagine your leg as a pendulum. It swings from one back to front and goes back again to form a complete cycle while you are walking or running. As this happens, the distance between your head and the ground and the hips angle changes. This two measurements is enough to allow the computer to determine whether you are walking or running.

Fig. 1 Sequence of walking person


Fig. 2 Sequence of a running person

For my project, I define the initial cycle as when the hip angle is zero. The key characteristic of a walking person is the hip angle is maximum when the head-ground distance is maximum in during the cycle. Whereas for running, both angle and head-ground are maximum. If you wonder why or how this can happen, it is because when you walk, both of your leg have contact with the ground while your legs spread. This causing the distance measured become less. While running, there will be a moment when you are 'on-air' or the proper term is double-float. While flying, you head is in a position bit higher than usual. You may not believe what I said, therefore I will present some results based on my project to illustrate further.

a) Double Support          b) Double Float

Fig. 3 Key difference between walking and running

Once you get the data required, you can used complicated classifier such as Neural Network or simple if else statement to recognise type of motion detected in the video.

Fig. 4 Plot of tracked point and angle hip of a walking person.

My next aim is to understand how to use Neural Network to automatically detect peoples behaviour based on the given data. Hopefully this can be done by this Friday.

The moral of the story, be worried guys! especially those who are living in Big Brother cities. You're being watched! Many surveillance operators nowadays have installed behaviour recognition module in their surveillance system [1, 2] . Obviously the software installed is more advanced and robust than my very simple and crude project. No matter what you do, how fast you walk or when did you left the bag unattended the computer can tell. Be a good citizen ok :-) .