Roof Types Visualization for Human Habitats Indicator

The objective of this paper is to show that the visualization of an urban landscape by 3D computer graphics can be used as indicators of human habitats on a worldwide basis when we think of a sustainable world in future. In the 1900s, in Japan, 2D digital urban maps became popular as commercial products such as automobile navigation map with GPS. They adopted the traditional map making technique consisting of map symbols and polylines. On the other hand, 3D CG urban map making has not yet established agreed principle or guidlines how to create. The simplest methods is to create a virtual house and a building as they are, using 3D CG architectural CAD system. This method demands enourmous amount of labor so that we can not create an urban map with thousands of houses and buildings. The second method is to express houses and buildings as boxes vertically projected on the closed polygon representing their building site. This method can show a geographical distribution of building sizes only. The database volume of this second method becomes ca. ten times larger than the counterpart 2D digital map of the same area. The auther proposes the third method. The actual buildings and houses have different each other but there are something in common such as roof shapes. In the world, we know there are about 30 roof types. Assuming that a house or a building has one roof and prepare 30 different prototype building models. We call them as 3D templates analogous to library parts used in CAD systems. A 3D CG urban map created by the third method has an advantage over the first and the second methods, not only from the database size viewpoint but also usablity as indicators of human habitats in the world. Shortly, (1) flat roof dominates in dry region. (2) cone shape roof in sem-dry region such as some part of Africa. (3) short eaves gable roof is dominant in humid region such as Western Europe and North America. (4) deap eaves and Asian mansard roofs are dominant in Monsoon Asia. (5) a modern high rise expressed by a tall box. This proposed method needs as large database volume as one by the second method but can show the cultural differences of cities. The auther describes the usability of the third method as a tool for environmental planning.