5-Comparison of IRS and LANDSAT Digital Data for Wetland Studies.

Abstract

IRS LISS-II and LANDSAT TM data of Gulf of Kachchh area of the same date (May 4, 1988) was used to evaluate LISS-11 data in comparison with TM data for wetland studies. This was done by (1) comparing radiance values of various wetland categories and (ii) analysing separability of wetland features. Similar points of 3x3 pixel size of various wetland classes, like, coastal water, reef area, mudflat etc. selected on both data sets. Radiance value for all features are higher in LISS-11 data than TM, this may be because of higher sun elevation angle of LISS-11 data. To check the separability of various wetland features, ratio of radiance values has been computed for every feature and compared with all remaining features. Here, the contrast between various categories is more or less same. However, TM bands 3 and 4 show slightly better discrimination for wetland features. Unsupervised classification was carried out using all 4 hands. In TM, coastal waters can be classified further as deep and shallow. Mudflat area gets mixed up with other categories in TM data. This may be because of different tidal condition. In principal component analysis both LISS-11 and TM data comes out as two dimensional (i.e. dimensionality of both the data is 2), TM data has higher variability than LISS-I1 data and so it has capacity to cover more classes. Overall, TM data is slightly better than LISS-II data for classification of wetland categories. This may be because of higher radiometric resolution of TM data.