Apart from the SIR-C Mission, radar polarimetry has been limited to a number of experimental airborne systems. Thus the data sets available for analyses are limited and those with sufficient ground truth data to support significant research efforts are even more rare. A number of geoscience applications have been studied by remote sensing specialists and the results are promising, especially for terrain classification. The number of these airborne data sets available for distribution and analyses is increasing and ENVISAT with its multi-polarization capability is also providing more data for analysis. RADARSAT-2 and other spaceborne systems with its multi-polarization and polarimetric modes will be supplying more data in the near future and thus the future for polarimetric applications development looks bright.
We discussed in the sections above how the polarimetric data can be used to generate multi-polarization products, such as HH, HV, and VV intensity images as well as making use of the full capabilities of the polarimetric data.
For some applications the availability of multi-polarization data may be enough to solve the problem, such as discriminating water from land and ice for mapping applications. In other cases, the use of the full capabilities of the polarimetric data to produce polarimetric parameters will be necessary. We are just beginning to exploit and understand SAR polarimetry for geoscience applications and the ongoing research and development efforts are expected to increase our knowledge and therefore use of polarimetric SAR data.
The following are some examples of the use of multi-polarization and polarimetry for SAR applications. The material selected was chosen on the basis of availability and suitability as an example for that particular application. In general the material was chosen from published work with the references provided. The material is not meant to necessarily be the best or most recent example as new results continue to be published.