We can consider “Openness of street” as one conventional comfort index. In order to evaluate this index, we emit rays from a certain point, and calculate the number of rays which can reach the sky without being obstructed by the other buildings or trees.
By carrying out calculations on whole points in a street, we can draw a distribution of “Openness index”. This Openness index is useful for simulate the influence toward surround buildings, and we can use this simulation when designing new buildings.