6. MERGING IMAGE ANALYSIS RESULTS 
Classification of differences shown on E-TM images may be 
problematic due to the difficulty to differentiate categories of 
cover classes; often a continuum in vegetation from low to high 
cover is observed and class boundaries cannot be properly 
identified. A solution is available by converting the image to an 
NDVI map. Cover classes that are distinctly visible on the 
image, but that looses that characteristic when converted to 
NDVI data form a complication. Following a dualistic 
interpretation approach solves both problems. 
An example is taken from part of the ETM-150/36 image, taken 
in August 1999 (Figure 4). An NDVI map was prepared, and 
based on comparing a mosaic of images, the NDVI scale was 
adjusted by the formula [0.70 (NDVI — 110) + 110], to reduce 
the level of greenness to NDVI's expected by end-Oct/early- 
Nov. (Figure 4). The NDVI map is based on a gliding scale; no 
attempt is made to link levels to cover classes. 
Comparing the NDVI map with the original TM image shows 
that the dark-reddish areas do not represent active-green 
vegetation. Consequently information loss took place. The dark 
areas however comprise of pine trees and shade; pine trees have 
a low chlorophyll activity. Both are very distinct classes and 
must be re-introduced onto the NDVI map. 
The ETM was subsequently classified through conventional 
routines to map trees and shade (Figure 4). Equally other cover 
types occurring in the area like snow, ice and clouds, were 
mapped. Superimposed on the NDVI image the classified image 
produced the merged product (Figure 4). 
  
  
  
  
  
  
Ro ; 4 à 
LE dent Ré au A i ws 
115 "bare 127 vegetated 451 
MRR TF T GS BRE 
IAPRS & SIS, Vol.34, Past 7, “Resource and Environmental Monitoring", Hyderabad, India,2002 
Classified 
trees and 
  
  
Figure 4. Merging Distinct Cover Classes with a Continuum 
NDVI Interpretation. 
After the product is prepared, GIS features as available on topo- 
sheets and on other higher-resolution images (e.g. 15 m Aster 
images), provides a map that is ready for local-level survey and 
land use planning exercises. An example of a village map 
prepared on the above lines is shown in Figure 5. 
  
       
    
     
     
  
       
Village boundary 
uL Streams 
Ex Villages 
  
== Ridges 
m Contours 
[I sf 
  
  
ab E | 
Very Bare to 50% Bare 
Poorly vegetated 
Somewhat vegetated 
Well vegetated 
Pine Trees 
  
  
  
  
Figure 5. Adding Features to an Interpreted ETM Product. 
[Miandam, located in the Swat valley, has an abundance of pine trees 
> 
especially on northern slopes. The main hillside, till the crest, has many 
hamlets, is less vegetated and is mainly used for grazing (cyan color on 
the image). Dispersed, many fields with annual crops were found 
(yellow); orchards are situated close to the streams (light green color).] 
    
     
    
     
    
    
     
     
     
     
    
   
     
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