Image Interpretation - ASAR

There are some general rules for SAR image interpretation as listed in ESA, 2006, p.28: -

1) Regions of calm water and other smooth surface will appear black, because the incident radar reflects away from the spacecraft.

2) Surface variations near the size of the radar’s wavelength cause strong backscattering.

3) A rough surface backscatters more brightly when it is wet.

4) Wind-roughed water can backscatter brightly when the resulting waves are close in size to the incident radar’s wavelength.

5) Hills and other large-scale surface variations tend to appear bright on the side that faces the sensor and dim on the side that faces away from the sensor. Mountains show this effect to the extreme, in part due to increased foreshortening.

6) Due to the reflectivity and angular structure of buildings, bridges, and other human-made objects, these targets tend to behave as corner reflectors and show up as bright spots in a SAR image.

7) A particularly strong response, say from a corner reflector, can look like a bright cross in a processed SAR image.