Cloud Removal of Optical Image Using SAR Data for ALOS Applications.
Experimenting on Simulated ALOS Data

Abstract

Cloud is always problem of optical remote sensing data. ALOS/AVNIR-2 images also will be affected. Microwave images are not affected by cloud. ALOS satellite has both optical and microwave sensor, similar resolution (∼10m). Therefore, main purpose of this study is to develop a method for removing cloud in ALOS/AVNIR-2 images based on ALOS/PALSAR data. This method is developed based on interpolating under cloud pixel values for ALOS/AVNIR-2 images. To remove cloud, it needs to be defined. A combination method of Total Reflectance Radiance Index (TRRI) and Cloud-Soil Index (CSI) is used to define cloud. Because around cloud pixels are mixture of cloud and other objects, that is very difficult to define. Therefore, the around cloud pixels are extended from cloud. Cloud shadow problem also is discussed in this study. Condition to apply this method is satisfied when objects in optical image and radar image change not very much. This method is experimented on simulated ALOS data from Landsat/TM and JERS-1/SAR images. Interpolated image is a free cloud and shadow image. Visual logic of objects is good. Original image and interpolated image are almost similar together. This method also can be applied for combination of two optical images to remove cloud if change of objects covered by cloud is not so much. Result of this study is a program with many functions like : define cloud, extend cloud, get shadow, remove cloud and so on. This is free software for every user.