Methods of performance evaluation for the supervised classification of satellite imagery in determining land cover classes
Souza,Carlos H. Wachholz de
Prudente,Victor H. R.
C.H.W Souza, E. Mercante, V.H.R. Prudente and D.D.D. Justina. 2013. Methods of performance evaluation for the supervised classification of satellite imagery in determining land cover classes. Cien. Inv. Agr. 40(2): 419-428. Satellite imagery, in combination with remote sensing techniques, provides a new opportunity for monitoring and assessing crops with lower cost and greater objectivity than traditional surveys. The present research employed Landsat 5/TM satellite imagery to identify the land cover classes in Cafelândia (Paraná, Brasil), a predominantly agricultural town. Five supervised classification methods (parallelepiped (PL), minimum distance (MND), Mahalanobis distance (MHD), maximum likelihood classifier (MLC) and spectral angle mapper (SAM)) were tested in this work. To assess the efficiency of the classifications, accuracy indices and error metrics obtained through total confusion matrices were used. The results indicated that the Mahalanobis and SAM methods generated the smallest errors for the four studied land use classes (soybean, corn, forest, and bare soil), with overall accuracy values of 88% and 86%, respectively, and kappa index values 0.83 and 0.80, respectively. The values of these methods for the applied metrics were 0.88 and 0.86 for the sensitivity index, 0.96 and 0.95 for the total specificity index and 0.84 and 0.81 for Matthews correlation coefficient, respectively. The different classification methods clearly exhibited large variations in their performance for land cover mapping. The use of measures obtained from the error matrix is a suitable method for comparisons of thematic maps.