基于遥感的城市化进程监测方法及其应用

【目的】利用不同分类精度的指数模型分析南京2001—2015年的城市化进程。【方法】借助2001年Landsat7 ETM+,2006、2010年Landsat5 TM及2015年Landsat8 OLI南京地区遥感影像数据,首先通过归一化差异水体指数(the modified normalized difference water index,MNDWI)提取水体信息,随后利用城市指数(the urban index,UI)、归一化建筑指数(the normalized difference built-up index,NDBI)、建筑指数(the index-based built-up index,IBI)、基于红光的建筑指数(the visible red-based built-up index,VrNIR-BI)、基于绿光的建筑指数(the visible green-based built-up index,VgNIR-BI)模型提取不透水层,结合最大类间差分法将影像分为建成区和非建成区两类,最后融合分类结果形成南京地区城市化专题地图。【结果】从验证结果来看,所有模型的总体精度均高于64.33%,其中UI、NDBI模型具有总体最高精度。UI模型精度最低69.67%(2001年),最高85%(2010年); NDBI模型精度最低72.00%(2001年),最高82.60%(2010年)。在UI模型和NDBI模型下城市化发展水平,分别从2001年的11.55%和17.66%攀升至2015年的20.50%和25.60%。【结论】在精度最高的UI指数和NDBI指数模型下,南京市除高淳区和溧水区之外的各个行政区的建成区增量前4名分别是江宁区、六合区、浦口区和栖霞区。

Monitoring methods and application of urbanization processes based on remote sensing

【Objective】To explore the accuracy of classification of different models and the urbanization process of Nanjing during 2001-2015, we used Landsat 5 TM imagery acquired in 2006 and 2010, Landsat 7 ETM+ imagery acquired in 2001, and Landsat 8 OLI imagery acquired in 2015, covering Nanjing City. 【Method】We computed the modified normalized difference water index(MNDWI)to mask out water bodies within the study area, followed by the extraction of the built-up areas and non-built-up classes via five urban index models(UI, the urban index; NDBI, the normalized difference built-up index; IBI, the index-based built-up index; VrNIR-BI, the visible red-based built-up index; and VgNIR-BI, the visible green-based built-up index)based on a maximum inter-class difference algorithm derived from the Landsat images. 【Results】The validation results indicated that the accuracy of all models was over 64.33%. Among all six models, UI and NDBI had higher overall mapping accuracy, and their overall accuracy was among the highest(85.00% and 82.60%)in 2010, and the lowest(69.67% and 72.00%)in 2001, respectively. By calculating the increment of built-up area from these two indices, the urbanization degree calculated from UI increased from 11.55% in 2001 to 20.50% in 2015, whereas the urbanization degree derived from NDBI increased from 17.66% in 2001, to 25.60% in 2015. 【Conclusion】Furthermore, without considering Gaochun and Lishui Districts, the top four districts in urbanization processes of UI and NDBI were Jiangning, Luhe, Pukou, and Qixia.