元胞自动机CA越来越多地被用于模拟复杂的城市系统,但这些模拟基本不考虑城市的发展密度。不同的城市发展密度会对城市的形态有很大的影响,有必要将城市的发展密度引进CA的城市模拟中,以获得更好的模拟结果。本文将密度梯度函数引进了CA模型的转换规则中,并定义'灰度’来反映状态的转换。利用该模型对不同可能的城市发展组合进行了模拟,为城市规划提供了辅助依据。
Most CA urban models assume densities to be uniform for all cells. This is not true in real cities because densities substantially vary from cities to cities and from urban centres to periphery areas. Development density which affects urban form is an important factor in urban planning. This paper presents a CA model that incorporates density gradient for the simulation of urban development of different urban forms. Development density is obtained from density decay functions and assigned to the cells when they are converted into developed ones according to CA transition rules. The model which is based on the concept of "grey cells" can be used as a planning model to explore various combinations of urban forms and development densities. This paper also evaluates and compares the development patterns generated by different density gradients. It is found that development scenarios with high-density development can significantly reduce the encroachment on agricultural land and other important environmentally sensitive areas.
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