Just under five years ago it seemed impossible to be able to use a simple and already widespread camera as a reliable monitoring tool for a design engineer. Today, thanks to the giant strides made by technology and IT evolution, this is no longer the case and what once seemed like science fiction is now reality, thanks to the innovative Photomonitoring technique. But how can you obtain reliable information through two simple images? This article illustrates the general principles of Photomonitoring and the main applicability criteria of this method, also through successful application examples.