Numata, Izaya 
  
4. DISCUSSION: 
A sub region of the 1997 Landsat TM image with different cover classes and the corresponding classified image from 
the multitemporal shade images covering 1987 through 1997 are shown in Figure 4. This example shows how one can 
readily summarize the spatial and temporal dynamics of land cover change over the more than a decade time frame. In 
the field, it was verified by interviewing farm owners that some of the stands in the class > 10 years of —use (non forest) 
selected as candidates for pasture, did not really follow “forest to pasture” conversion history, but followed either 
“forest-cropping-pasture” or “forest-cocoa-pasture”. 
There was some misclassification, as shown by comparing the classified image with the reference map obtained using 
ground trusting, associated with the characters of the shade fraction image as illustrated in Figure 6. Figures a-1 and a-2 
show the reference map and the classified image, respectively. The error area indicated by the arrow in a-2 results from 
converted area (b-1) with high shade fraction, as verified in the correspondent shade fraction image b-2. This 
misclassification can be associated with insufficient training for the classification, since the training area acquired for 
characterize the class 10 year-old was very small. Beside that, there are some possible factors that can produce a high 
shade fraction such as dark soil and clay texture; pasture recently burnt. Other causes of errors can be the confusion of 
primary forest with older second growth forest, and with deforested area where shades are due to topography. 
Considering the spectral confusion associated with physical characteristic of land cover types, it would be required 
more sophisticated spectral analysis to improve the classification, including other spectral fraction images beside the 
shade. As verified by Roberts et al (1998), pasture can be highly dominated by nonphotosynthetic vegetation fraction 
(NPV) and soil fraction. Physical characteristics of pasture such as a amount of glass plant and soil types, mixuture 
betweem pasture and second growth, can be interpreted based on NPV and Soil fractions, what is very difficult to do 
using only the shade image. 
LandsatTM - 1997 Classified Image 
   
      
  
   
  
  
: | 6-10years 
EH 10 years 
a = 10 years 
  
Fig 6. the misclassification and some factors of error . a-1) reference map; a-1) classified 
image; 5-1): landsat/TM1987; b-2) shade image fraction data derived from Landsat/TM1987 
  
1036 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 
  
  
  
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