Evaluation of ASTER performance for coral reef cover mapping : case study on Menjangan Besar and Menjangan Kecil Island, Karimunjawa Islands
Pramaditya Wicaksono & Sigit Heru Murti
The most widely-used remote sensing data for coral reef habitat mapping is Landsat series. However, due to the malfunctioned of the SLC (Scan Line Corrector) instrument, Landsat 7 ETM+ can no longer provide accurate data for coral reef mapping. There are other available remote sensing data for replacing Landsat 7 ETM+ and one of its kinds is ASTER. This paper explained how ASTER data could replace Landsat 7 ETM+ for coral reef cover mapping in Menjangan Besar and Menjangan Kecil Island of Karimunjawa Islands. Coral reef cover were divided into Very Good (>75% Live Coral Cover), Good (50-74%), Fair (25-49%), and Destroyed (<25%). In addition, other substrates are divided into Non- Coral Cover and Deep Sea. The methods used in this study were PCA (Principle Component Analysis), NDVI (Normalize Difference Vegetation Index), and Maximum Likelihood Classification. Furthermore, exclusion of blue band from Landsat was performed to make it fair with ASTER. Data from field measurement data were used for image re-classification and accuracy assessment. The results showed that Landsat 7 ETM+ was slightly better than ASTER and underlined that a slightly better spatial resolution will not always produce better accuracy if not followed by a better spectral integrity. The highest accuracy for Landsat 7 ETM+ was 73.80% from the combination of PC1, PC3, and NDVI while the highest accuracy for ASTER is 61.9% from the combination of PC2, PC3, and NDVI. To sum it up, ASTER is a good replacement for Landsat 7 ETM+ for coral reef cover mapping.
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