Pft [ErM E x 100

Where, p(^) = Spectral reflectance (reflectivity) at a particular wavelength.

Er(A,) = Energy of wavelength reflected from object

Ej(^) = Energy of wavelength incident upon the object

The plot between p(X) and X is called a spectral reflectance curve. This varies with the variation in the chemical composition and physical conditions of the feature, which results in a range of values. The spectral response patterns are averaged to get a generalized form, which is called generalized spectral response pattern for the object concerned. Spectral signature is a term used for unique spectral response pattern, which is characteristic of a terrain feature. Figure 5 shows a typical reflectance curves for three basic types of earth surface features, healthy vegetation, dry bare soil (grey-brown and loamy) and clear lake water.

---SPOT XS Multispectral Bands

i

Reflected Infrared

Figure 5. Typical Spectral Reflectance curves for vegetation, soil and water

Figure 5. Typical Spectral Reflectance curves for vegetation, soil and water

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