Error Propagation and Model Uncertainties of Cellular Automata in Urban Simulation with GIS

Errors and uncertainties are important issues in most geographical analyses and modelling processes. It is well known that errors popularly exist in GIS data. A variety of methods have been developed to measure error propagation in GIS. Cellular automata (CA) have been increasingly used for modelling geographical phenomena, such as urban development. Urban simulation frequently involves the inputs of a large set of spatial variables from GIS. The errors of data source in GIS can propagate through CA modelling processes. Moreover, CA models themselves also have modeling uncertainties because they are just the approximation of reality. These uncertainties also have impacts on the outcome of urban simulation. Identification and evaluation of these errors and uncertainties are crucial for the understanding and utilization of the simulation results of CA. This paper attempts to address these important issues which have not been well dealt with before. This can help urban modelers and planners to understand more clearly the meanings and implications of CA modelling.