Nguyen Dinh, Duong 
Closed mangrove forest 
MGR FI 
153 102,255 
M8 
D15 14.5 100 
T320 
H 30 180 
S 020 
END 
The output is organized in two ways. One is the raw classified data file (binary) accompanied by a legend file (ASCII) 
and the other is a classified image data file in WinASEAN format (Nguyen Dinh Duong, 1997). The second option is 
convenient for those who are using the desktop public domain image analysis software WinASEAN 3.0 developed by 
the author. To demonstrate the practical application of the proposed concept, the author has used TM data of South 
Vietnam for analysis. Two methods of analysis have been compared: maximum likelihood classification and the 
proposed automated classification. The automated classification program was also applied to GLI data simulated by two 
TM scenes of South Vietnam. The results of this study is shown in Figures 2,3 and 4. 
  
  
Figure 2. False color image of study area (TM data) 
The maximum likelihood classification was executed by selecting 47 different classes representing major land cover 
categories of the study area. After classification, the classes were merged to create 29 classes including cloud, shadow 
and unknown which agree with the classification scheme of the GASC algorithm. Comparing the results of both 
methods, one could recognize their difference mainly in classification of pixel which lay in an overlap between two 
classes. While in maximum likelihood method the decision is made based on the Bayes solution which requires 
Gaussian distribution of sample population( that is in itself not always true), the GASC algorithm classifies the pixels 
according to their spectral reflectance curve and threshold values. In the former method, the feature space of a class is 
an ellipsoid-like surface and in the latter method the feature space is an arbitrary shape limited only by the modulation 
of the spectral reflectance curve and prescribed threshold values. Based on analysis using a field survey and local expert 
knowledge it was seen that the second method gives a more natural result then the first one. 
  
990 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.