Light and Materials in Virtual Cities

Abstract  The level of accuracy required for physical models of materials and their interaction with light in virtual city models is an open question. We consider work that has been done to date on modeling architectural materials, the measurement of such materials in situ, and modeling of natural materials found in urban environments (e.g. snow, ice, and mud). We identify gaps in currently available data, in current technology for specifying materials on large sets of buildings and rendering complex materials on a large scale. We also consider illumination of cities – both day lighting and the natural and manmade illumination at night. We identify issues related to night illumination, where assumptions about adapting to light source spectra and sensitivity to color that are made for daylightmay not hold.