Low cost documentation for the knowledge of the city.

Evaluation and preservation of cultural heritage in the XXI century is inextricably connected with the innovative processes of gaining, managing and using knowledge. The continuous technological advancement and in particular the great digital revolution offer new research tools that are easily applied to science. The development and perfecting of techniques for acquiring and elaborating models made them pivotal elements for popularizing information on objects on the scale of architectonic structures. These technologies therefore become absolutely essential for the cognition and preventive conservation in case of disasters, such as earthquakes, the effects of climate change, extreme weather and other disasters. Being low cost technologies that enable low cost and speedy acquisition, they are also very useful in reality. It’s the relationship between software and hardware devices that help us record the undergoing changes of the survey in an important moment of transition from a traditional approach to one closely connected with the huge potential inherent in digital technologies. Recently, the dense stereo matching or images based modelling technologies have become a valid instrument for surveying and representing architecture.