Essential steps in Remote Sensing

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Remote Sensing Method

1. Image Display

2. Registration and Rectification

3. Contextual Enhancement

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4. Multiband transformation: Indices

Multiband transformation techniques are used to create a new band for enhancing a feature of interest, reducing data size and redundancy. Multiband transformation techniques require more than one band of data and use the spectral information found in the multiple data bands. Indices and principle component analyses are multiband transformation techniques. Indices The following indices are commonly used.

Indices	Equation
Vegetation Difference Index	IR-R (infrared - red)
Vegetation Index	IR/R (infrared/red)
Normalized Difference Vegetation Index (NDVI)	(IR-R)/(IR+R)
Iron Oxide Ratio	R/B (red/blue)
Clay Mineral	Mid-infrared (1.55-1.74 micron) / Mid-infrared (2.08-2.35 micron)
Ferrous Mineral	Mid-infrared (1.55-1.74 micron)/Near Infrared
Mineral composite	Mid-infrared (1.55-1.74 micron) / Mid-infrared (2.08-2.35 micron) Mid-infrared (1.55-1.74 micron) / Near Infrared Near Infrared/Blue
Hydrothermal composite	Mid-infrared (1.55-1.74 micron) / Mid-infrared (2.08-2.35 micron) Red / Blue Near Infrared / Red

The following SPOT image illustrates the NDVI. The brighter values represent the vegetation, agriculture and forest area, and the darker values represent the non-vegetation area, road, harvested agriculture field, river and urban area.

4. Multiband Transformation: Principal Component Analyses

5. Classification

Unsupervised method or Clustering

Supervised classification