A comparative study on spatial and spectral resolutions of satellite data in mapping mangrove forests
Mangrove forests in the western Waitemata Harbour, Auckland, New Zealand were mapped into lush and stunted categories from SPOT HRV and Landsat TM images at 10, 20 and 30m using the maximum likelihood method. It was found that the TM-generated results were the most accurate at 95% for lush mangroves and 87.5% for stunted mangroves. Their corresponding accuracy levels were lowered to 77.5% and 67.5% in the 20m SPOT XS-derived results. Both percentages were improved to 80 after the PAN band was incorporated in the classification at 10m. These results suggest that a high spectral resolution is more important in accurately mapping mangroves in a temperate zone than a fine spatial resolution because it enhances the interpretability of non-mangrove vegetation and thus increases its confusion with mangroves.