Visibility maps of Turin. Including atmospheric conditions in viewshed analysis of DSMs

High-rise buildings affect the skyline of a city and thus the human perception of urban spaces. From which points can a building, or parts of the building, be seen? The answer requires viewshed analysis of raster or vector 3D city models. Visibility is not just a geometric exercise in which lines of sight are calculated using standard GIS tools. Visibility and perception of space are also determined by atmospheric conditions, contrast between foregrounds and backgrounds including the sky, visual acuity and psychological aspects. Here, the authors present a simple but accurate method for generating visibility maps based on the above criteria and demonstrate its effectiveness for a newly erected skyscraper in Turin, Italy.