Research On Urbanization Level Measure Based On Low Light Level Data

Since 21 st century, the process of urbanization in China has accelerated gradually. The technology of remote sensing can reflect the land use and land cover conveniently, objectively and continuously. Combining remote sensing with administrative district statistics has become an effective method to estimate the level of urbanization. The adoption of Nighttime Light(NTL) images has become a new technical means for urban studies at large scale and has been widely concerned, which can reflect human activities broadly, economically, intuitively and exactly.Using DMSP/OLS nighttime light data and choosing mainland China as study area, a research on methodology for extracting distribution of urban areas based on biophysical composition index was carried out. In terms of the results, temporal and spatial variation of urbanization level in mainland China from 2000-2012 were analyzed. Detailed works and main conclusions are as follows:(1)Based on the existed method, nighttime light data from 2000-2012 were corrected according to the corrected coefficients, which make DN value of multi-year NTL data comparability.(2)As NDVI cannot distinguish impervious surface from soil effectively, this paper extracted the information of urban land in mainland China through introducing BCI and combined difference idea with SVM classification method, and conducted the comparison analysis and precision evaluation in the classification results between previous studies and SVM based on NDVI method in typical cities.(3)Chinese mainland, eight economic areas and six typical urban agglomeration were chosen as study objects. And the analysis of the variation of Chinese urban level was carried out. Results showed: the urban level of East China is higher than West China and coastal areas are higher than inland areas; the urbanization of Jingjinji, Hangzhou and Hohhot agglomeration are fast, while Harbin-Changchun, Chengdu and Nanchang agglomeration are slow respectively.