Sky View Factor Analysis

Sky view factor (SVF) analysis quantifies the fraction of the overlying hemisphere of sky that is visible from a given point on the ground, ranging from 1.0 in a wide-open field to near 0 at the bottom of a deep, narrow street canyon. It is a central geometric descriptor in urban climatology because the amount of visible sky governs how much longwave radiation a surface can lose at night, directly shaping the urban heat island. The measure was put on a rigorous footing by Timothy Oke's 1981 work linking canyon geometry to nocturnal urban warming.