A series of GIS-based spatial reclassification procedures were
conducted to refine the outputs from the stratified image classification.
Firstly, we overlaid the wetland layer generated from the
NWI datasets for each year with each of the classified land use/
cover map.
This can help address the significant spectral confusion
between the wetland and forest classes during the supervised
classification.
The wetland polygon data for each year were
manually modified from the NWI 2012 datasets with reference to
the satellite imagery and aerial photos.
We then converted the wetland polygons of each year into binary layers that were then
overlaid with the classified map to produce the wetland classes.
Therefore, all the classified forest pixels that overlap with the
wetland layer were reclassified as wetland in the output maps for
both years.