Remote Sensing of Soil Moisture
HERTZ
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THERMOGRAPHY RADIOMETRY, SENSING
RADAR
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TRANSMISSION
THROUGH
ATMOSPHERE
PRINCIPAL
TECHNIQUES FOR
REMOTE SENSING
371
Figure 14.1: An illustration of the electromagnetic spectrum showing the relationship between
wavelength and frequency, the common names for spectral bands and the relative atmospheric
transmission: The principal techniques used in remote sensing are also shown for their respective
spectral region (After Engman and Gurney, 1991).
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Figure 14.2: Planck's law brightness curves for blackbodies at T = 30K and T = 300K (After
Manual of Remote Sensing, 1983).
Remote sensing techniques mainly use 3 regions of the electromagnetic spectrum: the visible
band (0.40-0.70 Jim), the infrared band (0.7-100 Jim) separated into near, middle, far and