Measurement and Analysis of Urban Growth
The process of mapping urban growth results in the creation of abstracted and highly-simplified change maps of the study area (as shown in Fig. 5.5). Examining these thematic change maps, even cursorily, one may see that expansion of built-up has different signatures: some areas are very compact while in others more open space between built-up areas. In some of the areas the boundary between the built-up and non-built-up is rather sharp, while in others these classes dissolve into each other. One can also see the infill of the open spaces between already built-up areas that results in their consolidation; or, one can understand whether the city is becoming more monocentric or polycentric over time. Surely, one can grasp these patterns intuitively, but they fall short of providing solid evidences for debating and deciding upon the future. To describe these different patterns intelligently, to understand how they change over time, to compare one subpart with others, or to explain the variations among these patterns statistically, we need to select quantitative measures that summarise one or another of their properties. Recently, urban change detection focus has been shifted from detection to quantification of change, measurement of pattern, and analysis of pattern and process of urban growth and sprawl.