Spatial Expansion Characteristics And Analysis Of County Central Cities In Tangshan District

Based on Landsat series data sources,this paper summarizes the definition of built-up area in the form of literature review,explores the method of boundary division,implements the remote sensing image extraction of the built-up area,and analyzes the spatial expansion of the county central city.Two extraction methods were selected.In terms of spectrum extraction method,support vector machine method with better accuracy of building classification was selected,and the secondary extraction was carried out by combining rule-based object-oriented method to get the information of county central urban area;in terms of texture extraction method,TNDBI index was established by analyzing the band trend of texture average value of training samples in gray level co-occurrence matrix,and the principle of NDBI index was combined to re-select training samples carry out supervision and classification and carry out post classification processing to get the built-up area of the center.Finally,the central built-up area was obtained by analyzing the results of two extraction methods.Based on Arc GIS platform,this paper analyzed the spatial expansion of Zunhua,Qian'an,Qianxi,Laoting,Luanxian,Luannan and Yutian,and constructs regression equation to evaluate the fitting degree of urban expansion and economic index growth.In the selection of regression equation,the paper studied and compared the anti-difference effect of multiple least squares method and multiple robust estimation method.It was found that when the difference between data was small,the fitting equation of robust estimation was more accurate,otherwise the fitting degree of the two methods was similar.The spatial expansion of county-level cities in Tangshan is quite different,and each county was expanding in the direction of favorable urban development.The driving factors affecting the development of county-level cities were government tax and industrial institutions.Affected by the county's own environmental factors,the spatial expansion of each county was unbalanced.Influenced by the concept of spatial expansion of big cities,the characteristics of county development disappeared,which required a balance point of comprehensive own conditions and radical development.Figure 22;Table 17;Reference 42.