Analysis Of Urban Structure Development In Hangzhou Based On NPP-VIIRS Night Lighting Remote Sensing Image

Under the background of the rapid development of urbanization,the spatial structure of the city has undergone tremendous changes.From different spatial scales,the changes are mainly reflected in two aspects,one is the expansion of the urban built-up area,and the other is the heavy component of the urban internal spatial structure.The expansion of urban built-up areas is mainly manifested in the increase of various types of land use in cities,such as population and land use,public service land,and road traffic facilities.When this rapid expansion is not guided by urban development planning,blindly expanding expansion will have many negative impacts on the surrounding environment and urban human activities.Therefore,quickly and accurately grasping the scope and development direction of urban built-up areas can provide basic data support for urban development planning.On the other hand,changes in the spatial structure of the city have become extremely complicated as the population has grown dramatically.Among them,the urban residential structure as an important part of the urban internal space structure is particularly important for describing the changes in the internal structure of the city.Housing vacancy rate is often used to analyze urban residential structure changes.It not only reflects the actual occupancy of the house,but also reflects the spatial distribution of the urban residential structure to a certain extent.There is currently no statistical data on this project in China,and field survey methods are used in foreign countries.Therefore,mastering the changes in urban housing vacancy rate can accurately understand the changes in urban residential structure and provide a basis for urban development planning decisions.With the development of remote sensing technology,especially the rapid development of nighttime lighting remote sensing images,its related data has been used for many times to study urban development and social and economic activities.At present,there are two main types of nighttime remote sensing data,namely DMSP-OLS stable nighttime lighting data and NPP-VIIRS nighttime lighting data.Most of them are used for estimation of indicators such as gross national product,electricity consumption,carbon dioxide emissions,and city freight volume.Most of these studies use nighttime lighting data combined with corresponding spatial analysis algorithms to describe socioeconomic activities and urban development.This paper analyzes and summarizes the existing research situation,and proposes the use of NPP-VIIRS nighttime remote sensing image data to analyze the structural changes of urban development.(1)Firstly,according to the spectral characteristics of nighttime remote sensing image,the logarithmic transformation is used to process the nighttime light remote sensing data,and the urban built-up area of Hangzhou is extracted.The Landsat remote sensing image and the confusion matrix are used to verify the extracted built-up area results.Finally,the nighttime lighting remote sensing image map of the urban built-up area of Hangzhou from 2012 to 2016 is extracted.It is found that the urban development of Hangzhou from 2012 to 2016 is mainly in the east in space,showing a trend of expansion in the northeast and southeast,but the increase is not large,and has the characteristics of urban development with obvious "axis along the river".(2)Secondly,using the night light remote sensing data,Landsat remote sensing image data and related statistical data to propose the housing vacancy rate estimation model,and based on this,analyze the development and changes of the residential structure in Hangzhou.The study found that the residential space in Hangzhou showed a stable and outward trend from 2012 to 2016,and it mainly showed a trend of westward expansion,a way of expansion and a certain path dependence.The research results show that the development of urban built-up areas in Hangzhou from 2012 to 2016 is mainly in the east,showing a trend of expansion in the northeast and southeast.The living space of the city is in a stable and contagious stage.At this stage,the urban residential structure shows that the living space is expanding continuously,the structure of the central urban area is stable,the outer sub-circle expands outward,and the outer suburbs are uniformly spread out with the center of the district and the county as the core.These changes are basically consistent with the development plan of Hangzhou.