Hi, I have a pal who had done some research and prototype of how to implement a face tracking system similar to what is done by the police forces in North America, source code here [ https://github.com/chiteri/facetracking ] In a nutshell, what it does is that its has a back-end for learning of faces using some machine learning algoriths (Fast-fourier tranforms mostly I think) in separate libraries. You can feed it with faces of known criminals from a database. After that all you need is a Mobile camera, preferably mounted on a police car simply moving around the city. If it finds a match it notifies the relevant authorities, via e-mail or SMS for instance. In no time, you have the whole place crawling with cops, police dogs, helicopters, etc. Mad fun!! Martin ---- SHD Nairobi [ nairobi.sciencehackday.com/ ]