基于Landsat-8 OLI数据的青海湖水体边界自动提取

Automatic Extraction of Qinghai Lake Boundary from Landsat-8 OLI Data

在青海湖Landsat-8OLI遥感数据水体光谱特征分析的基础上,利用绿光(Band 3)和近红外(Band 5)两个波段,借助ENVI内置IDL语言的数据转换规则提出了一种新的水体提取方法IDLWI,加大影像中水体与非水体的灰度差,以利于水体识别。而后在水体识别的基础上,基于Canny算子进行水体边界矢量数据自动提取。分别运用"MNDWI(改进的归一化水体指数)+Canny算子"、"谱间关系法+Canny算子"和"IDLWI+Canny算子"提取青海湖边界,经高分影像目视判别和GIS空间缓冲区分析。结果表明:"IDLWI+Canny算子"提取出的青海湖湖体边界在位置准确性和连续性方面有明显的改进,尤其可以较好地提取出青海湖水体与湖滩地的边界(包括水体内裸露土地边缘)。

based on the analysis of water spectral signatures in Landsat-8 OLI remotely sensed image covered Qinghai Lake and ENVI software,a new method referred to as the ＂IDLWI＂（Interactive Data Language Water Index）was put forward to identify water body.The method is to amplify the digital number（DN）values between water and non water body by the difference operation between the squared green band（Band 3）and the squared near-infrared band（Band 5）,with the help of IDL language data conversion rules built in ENVI software.On the basis of water identification,an improved Canny operator was applied to automatically extract Qinghai Lake boundary in the format of vector.In this paper,Qinghai Lake boundary was extracted by means of MNDWI plus improved Canny operator,the law of spectrum relevance plus improved Canny operator and the squared-difference method plus improved Canny operator respectively.The extracting results were verified by high spatial remotely sensed image and GIS spatial analysis,and it shows that there is an obvious improvement in accuracy and continuity compared to the methods of MNDWI plus improved Canny operator,and the law of spectrum relevance plus improved Canny operator.Besides,the method we proved did well in extracting the boundaries of water which is linked to overflow land and wetland.