鍏抽敭璇�: 鍩庡競褰㈡��, 閬ユ劅鍥惧儚, 鍒嗗舰, 鍒嗙淮, 鍗婂緞娉�, 鍖椾含

Abstract:

This paper presents a study on the fractal urban form of Beijing.We use the city built-up area to define the urban form.It includes all the built-up area of houses,squares and roads,but the roads connecting central cities are not included,nor the water and vegetation.The data is obtained from the Landsat TM images of Beijing.Two TM scenes from 1984 and 1999 are used to cover the city and its adjacent areas.Based on the unsupervised classification using the IMAGINE ERDAS 8.6,the authors conducted an aborative correction on the map so that the classification is accurate enough. ESRI ARC GIS 9.0 is used to get the area data.The authors use the area-radius relationship method in this paper.In this view,the fractal dimension is a way to clarify the convergence and decentralization of urbanized area. The authors found that the city of Beijing bears clear fractal characteristics.The computation shows that there exist double scaling range.The first scaling range is good to reveal the fractal evolution of Beijing.The scaling range is 8km in 1984 while it is 14km in 1999.The extension of the scaling range shows that the fractal characteristic in 1999 is better than that in 1984.The dimension values also indicate the building density of Beijing.In 1984,the density remains almost unchanged in a region of 10 km distance from the center(Tian'an Men).In 1999,the building density increases from the center to a region with a radius of 16.5 km.Both of the building densities decrease outside the corresponding ranges of 1984 and 1999.The fractal model from the area-radius relationship method in this paper has important theoretical significance,which needs further studies. The fractal computation in this paper has important practical significance. The scaling range of a city is a special variable that carries individual characteristics.It is also a comparable variable among cities.Based on this,the authors identified a new city definition using the scaling range.The new definition can avoid the subjective and incomparable factors of the ordinary definition method.The scaling range also has important theoretical significance.

Key words: urban form, remote sensing image, fractal, fractal dimension, area-radius relationship method, Beijing