Manzul Kumar Hazarika 
  
4.2 Road Passing Through a Paddy Field 
A road passing through an area with uniformly distributed vegetation, like paddy field becomes prominent due to their 
different reflection characteristics. A section of road with a width of 35m (Figure 2), passing through a paddy field can 
be seen very distinctly in ADEOS Panchromatic data. There is a very good background contrast throughout the road 
section and edges of the road can be identified clearly. SPOT Panchromatic data also provide a clear picture of the road. 
Due to the low resolution, in the case of ADEOS Multispectral data and LANDSAT TM data, edges of the road section 
is not prominent, though the road can be clearly identified as shown in the figure. SPIN-2 data is not available for this 
area. 
ADEOS Panchromatic SPOT Panchromatic ADEOS Multispectral LANDSAT TM 
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
Figure 2 A section of road passing through a paddy field 
4.5 Road Passing Through an Urban Area 
Images in Figure 3 show a section of road through an urban area. Ground width of this road section is 64m. Irrespective 
of spatial resolution, the section of road marked by a circle can not be identified clearly in any of the images. However, 
in certain sections, where background is not structural material, the road can be identified. Thus, if a road passes 
through such an urban area which gives similar spectral signature as construction materials, it is very difficult to 
identify the road. In such cases, there is a need to look for certain sections of the road with a background other than man 
made materials, for identification. 
ADEOS Panchromatic SPOT Panchromatic ADEOS Multispectral LANDSAT TM 
  
  
     
   
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Figure 3 A section of road passing through an urban area 
4.4 Locating Bridges on a Road 
A bridge with two parallel roads of 10m width each, one for up coming and another for down going vehicles, with a gap 
of 5m in between (25m in total) can be identified separately in ADEOS Panchromatic and SPOT Panchromatic data. 
ADEOS Multispectral and in LANDSAT TM data can not distinguish these two parallel roads separately. SPIN-2 data 
is not available for the location of the bridge. 
4.5 Estimation Of Road Width 
4.5.1 Estimating Width of Roads Using Analog Method 
Estimated width of various road sections using different sensors are shown in Table 2. Using SPIN 2 data, a 64m wide 
road (Figure 4) is measured and it varies from 64m to 66m (8.00mm to 8.25 mm), giving a maximum error of 2m. The 
same section of road varies from 60m to 70m (3.00mm to 3.50mm) in ADEOS Panchromatic and SPOT Panchromatic 
data. In both of the cases, maximum error found to be 6m. Due to low resolution, edges of the same road section are not 
very prominent in ADEOS Multispectral data and LANDSAT TM data. In ADEOS Multispectral data width of the road 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B3. Amsterdam 2000. 369