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negative for vegetation and positive for built-up area and bare land area. Further
mathematical expression like root function for cluster of different objects.
8.4.1.4 BUI
The Built-Up Index is one of the new indices using multiple band like Red (Band 3),
SWIR1 (Band 5) and SWIR2 (Band 7). It can efficiently demarcate the built-up area of
urban centres. The value close to 0 denotes the built-up area (Figs. 8.2, 8.3, 8.4 and 8.5).
8.5 Results and Discussion
Comparison among different kinds of built-up indices has been done by different
researchers. And they found that EBBI (with its threshold) is quite good with their
moderate resolution satellite data like Landsat OLI. Urbanisation in the major cities
of West Bengal is very much unorganised. Here, considering the NDBI value,
Kolkata stands first but compared to the year 2011, it is found that Siliguri has the
highest decreasing rate of NDBI value for the last decade (Table 8.6). In the case of
Fig. 8.2 (a) Normalised Difference Built-Up Index (NDBI), (b) Normalized Difference Vegetation
Index (NDVI), (c) Enhanced Built-up and Bareness Index (EBBI) and (d) Built Up Index (BUI)
of Kolkata
R. K. Paul and P. Patra