Analyzing 3D urban development in Taipei City

Population is currently growing and the urban area are expanding around the world, so the urban sustainable development therefore becomes an important issue in recent years. Previous studies have used satellite imagery to explore the land use change and analyzed urban development, and they mostly investigated the change of urban development in the planar dimension, while few have been focused on the development of urban structure in the third dimension - the vertical dimension. The change of the building structure is not only the built-up area but also the height of building. In Taiwan, according to the land use monitoring data, the urban development is becoming slow in the past two decades in Taipei City, although the percentage of urban area has increased from 21.7% in 1980 to 41.3% in 2010, and the urban area is considered to be saturated. This study argues that in an intensively developed urban, if lands available for new constructions become limited, the urban development could shift from 2D to 3D - the building height. This study explored the development process of urban area and urban floor in Taipei City, by analyzing the 3D building models of the city from 1969 to 2007. The preliminary results show the urban area and building density represent an increasing trend before 1990s and slow down sharply after 1990s. However, at the same time the building height of the urban shows an inverse trend against the urban area, which has a significant increase after 1990s, indicating that urban development in Taipei City has converted from planar expansion to vertical growth. This study suggests a new direction of urban study, especially for highly developed cities such as Taipei City, if 3D urban data can be available.