基于多时相夜间灯光和光学遥感的广西城市格局时空动态变化

Spatiotemporal dynamics of urban patterns in Guangxi based on multi-temporal night-light and optical remote sensing data

以广西桂林、柳州、南宁3个城市的建成区为研究区,利用阈值分割法分别对DMSP/OLS、NPP/VIIRS、Landsat数据提取城市建成区,根据夜间灯光总强度指数(TNLI)、平均灯光强度指数(I)以及综合夜间灯光强度指数(CNLI)的灯光特性分析广西三城城市化水平,通过计算光学影像的归一化建筑指数(NDBI)、建筑用地指数(IBI)、仿建筑用地指数(SIBI)、综合加权建筑指数G采用阈值法提取3个城市1992、2000、2009和2017年4个时间段的建成区,最后利用城市扩张速率、强度指数和空间重心位置转移定量分析25年来广西三大主要城市建城区时空演变特征。结果表明:1)广西城市化水平不断提高;2)利用陆地卫星遥感与夜光遥感对城市建成区提取具有一定可信度,陆地卫星提取的总体准确精度达到了93%,但提取的整体精度比夜光遥感低,夜间灯光数据的总体精度都在83%以上,总体提取精度达到了96%;3)广西三大主要城市的城市化进程速度在加快:南宁在1992—2017年城市扩展速度由11.88上升至34.4,柳州在此期间由6.95上升至21.74,桂林城市扩展速度由8.11上升至16.74。以上结果同时说明了广西城市发展整体呈现上升趋势,建成区的空间扩展范围随时间推移表现出高强度增长模式,这与广西规划的城市化进程发展趋势一致。

To study the built-up areas of three major cities in Guangxi,Guilin,Liuzhou,and Nanning,the threshold segmentation method was used to extract urban built-up areas by DMSP/OLS,NPP/VIIRS,and Landsat data respectively.According to the total light intensity index(TNL),the average light intensity index and the comprehensive night light intensity index(CNLI),the urbanization level of the three cities in Guangxi were analyzed.By calculating the normalized building index(NDBI),building land index(IBI),imitation building land index(SIBI),and comprehensive weighted building index G of optical images,the threshold method was used to extract three cities in four built-up areas in 1992,2000,2009 and 2017 over a period of time.Finally,the spatial and temporal evolution characteristics of the three cities over the past 25 years were quantitatively analyzed by urban expansion rate,intensity index and spatial center of development shift.The results show that(1)Guangxi urbanization level is continuously improved.(2)The use of Landsat and night-light remote sensing data has certain credibility.The overall accuracy of Landsat extraction reaches 93%,but the overall accuracy of extraction is lower than that of night-light remote sensing.The overall accuracy of night light data is above 83%,and the overall accuracy reaches 96%.(3)The urbanization process of the three cities is accelerating.Nanning urban expansion rate increased from 11.88 to 34.40 during 1992 to 2017.Liuzhou increased from 6.95 to 21.74 during 1992 to 2017.Guilin urban expansion rate increased from 8.11 to 16.74 during 1992 to 2017.The overall urban development of Guangxi presents an upward trend.The spatial expansion of built-up areas shows a high-intensity pattern,which is consistent with the development of Guangxi urbanization.