COMBINATION OF ALOS PALSAR AND SPOT 5 FOR LAND COVER MAPPING - CASE STUDY OF CA MAU, VIET NAM

摘要

Optical remote sensing imagery is often used for land use, land cover mapping and monitoring. However, the data is limited due to the frequent cloud cover in tropical regions such as Vietnam. The microwave remote sensing data is utilized to overcome this problem. The aim of this study is to interpret the gap caused by cloud cover on SPOT image by the microwave data in order to improve the accuracy of the land cover map. The ALOS PALSAR and SPOT 5 images of Ca Mau area, Vietnam were chosen for this study. Firstly, several filters such as Lee, Frost, Gamma, Median and local Sigma filters were applied to the radar image so as to reduce the noise and enhance the image quality. Secondly, the microwave and optical data were geo-referenced to VN-2000 coordinate system. After that, the PALSAR image was combined to the SPOT imagery and data fusion techniques such as NDVI, PCA (Principal Component Analysis) and Color Composite (HIS and Brovey) were used. Then unsupervised and supervised classification methods were applied to the results of the data fusion to generate a land cover map with various categories. The use of the hierarchical analysis, unsupervised classification result of radar image can be grouped following the supervised classification of SPOT. Finally, the result of fused image classification was compared to the SPOT5 classification and edited to establish land cover map. During the processing and mapping steps, the role of ALOS PALSAR data in land cover mapping was estimated.