HY-1C卫星海岸带成像仪在岛礁监测中的应用

Application of HY-1C satellite coastal zone image in island and reef monitoring

利用海洋一号C卫星(HY-1C)具有宽幅、宽光谱、重访周期短等特点,以我国西沙群岛永乐环礁为例,开展岛礁地貌遥感信息提取研究。通过卫星海岸带成像仪(CZI)波段直方图、信噪比等计算,HY-1C卫星CZI的四个波段中蓝波段的反射比均值为28.53,影像信噪比0.84,对岛礁地貌的表现最为明显;而红波段对岛礁的信息表现一般。总体上CZI传感器可表达珊瑚岛礁信息,利用非监督分类方法可获得岛礁信息,但对于水下礁坪等信息易误判。为充分利用HY-1C卫星的波段信息,利用层次分析法,建立各波段对岛礁信息表达的权重,从而获得建立权重后的图像,基于此,采用监督分类方法对岛礁信息进行提取,有效地提取了自然岛、砂质岸滩、水下礁坪、暗沙、冲沟等信息,Kappa系数为89.97%。可满足在中分辨率尺度上,对大范围、高频度的岛礁调查要求。

Taking Yongle Atoll in the Xisha islands of China as an example,the remote sensing information extraction of island and reef geomorphology was carried out by using the characteristics of HY-1C satellite,such as wide range,wide spectrum and short revisit period.Through the calculation of coastal zone images(CZI)band histogram and signal-to-noise ratio,the mean value of the blue band in the four bands of the HY-1C satellite CZI is 28.53,and the signal-to-noise ratio of the image is 0.84,which is the most obvious manifestation of the island and reef landform;However,the information of islands and reefs in red band is general.In general,CZI sensors can express the information of coral islands and reefs,and the information of islands and reefs can be obtained by unsupervised classification method,but it is easy to misjudge the underwater reef flat and other information.In order to make full use of the band information of HY-1C satellite,the analytic hierarchy process was applied to establish the weight of each band to the island and reef information expression,so as to obtain the image after the weight was established.Based on this,the supervised classification method was explored to extract the island and reef information,effectively extracting the natural island,sandy beach,underwater reef flat,hidden sand,gully and other information,and the Kappa coefficient was 89.97%.It could meet the requirements of large-scale and high-frequency island and reef survey on the medium resolution scale.