Venice: A Test Field for Urban Historical Centers Surveying with SLAM

In historical cities, it is often impossible to navigate with traditional MMS, and it is not appropriate to perform photogrammetric flights with drones at very low altitude. Terrestrial photogrammetry is also not feasible since the streets are very narrow and the buildings very tall. In the past, Iuav's Geomatics Laboratory has tested the possible application of spherical photogrammetry, i.e., the use of spherical chambers with which the geometry of taking in narrow spaces is simplified. The results, although promising, proved to be inferior to those achievable with the SLAM technique. The historic center of Venice, in which vehicles are not allowed to circulate and in which the presence of 'calli' (streets whose width often does not exceed 2 meters) is numerous, is the ideal field of application for testing SLAM techniques and then applying them in other urban contexts (ancient boroughs) that have an urban morphology similar to that of the lagoon city. In Venice, moreover, SLAM has also been used to survey canals in which buildings face directly without the presence of banks. SLAM in fact can have as carrier not only the operator walking, or in a vehicle, but also in a boat. The paper presents the urban survey in different spatial configurations (calli, canals) using different commercial solutions and a prototype realized in the Geomatics laboratory by the authors.