slide 32

Different structures of land objects have different sensitivities to polarization modes. There are three types of scattering: rough surface, double bond, and volume scattering. Rough surface scattering occurs on rough surfaces like natural land and bare soil. Double bond scattering happens on vertical surfaces like man-made buildings or tree trunks. Volume scattering occurs when signals bounce multiple times in objects like canopies or dense vegetation. The figure illustrates these three types. In rough surface scattering, the VB polarization mode has more power scattering back to the sensor, making the SAR image brighter. For man-made buildings, HH has more power scattering back. In volume scattering, HV and VH have more return power. With four polarization modes, we get four SAR images that show different brightness due to the sensitivity of polarization modes to land objects. This allows for classification, but the use of different polarization data depends on the SAR polarimetric a Different structures of the land objects have their sensitivity of the polarization mode. There are three types of scattering. Rough surface scattering, double bond scattering, and volume scattering. The rough surface scattering happens when the surface is rough, such as natural land and bare soil. The double bond scattering happens when the surface is vertical, such as man-made buildings or tree trunks. The volume scattering happens when signals bond several times in the object, such as the canopy or dense vegetation. The figure illustrates the three types of scattering. For the rough surface, the polarization mode VB has more power scattering back to the sensor. This means the amplitude of the SAR image in VB mode is brighter than that in the other mode. In terms of man-made buildings, HH has more power scattering back to the sensor. For the volume scattering, HV and VH have more return power. If we have four polarization modes, we have four SAR images. Due to the sensitivity of polarization modes over different land objects, the four SAR images show different brightness. For example, tree canopy is only bright in HV or VH mode, and is dark in VB and VHH. So we can do classification. The use of different polarization data is related to the application of SAR polarimetric. In this course, I won't talk about this.