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The interferometric coherence is a measure of the correlation between two SAR images and constitutes a commonly used estimator of the phase quality. Its estimation requires a spatial average within a 2-D window, usually named as multilook. The multilook processing allows reducing noise at the expenses of a resolution loss. In this letter, we analyze the influence of the multilook size while applying a polarimetric optimization of the coherence. The same optimization algorithm has been carried out with different multilook sizes and also with the nonlocal SAR filter filter, which has the advantage of preserving the original resolution of the interferogram. Our experiments have been carried out with a single pair of quad-polarimetric RADARSAT-2 images mapping the Mount Etna's volcanic eruption of May 2008. Results obtained with this particular data set show that the coherence is increased notably with respect to conventional channels when small multilook sizes are employed, especially over low-vegetated areas. Conversely, very decorrelated areas benefit from larger multilook sizes but do not exhibit an additional improvement with the polarimetric optimization.

The interferometric coherence is a measure of the correlation between two SAR images and constitutes a commonly used estimator of the phase quality. Its estimation requires a spatial average within a 2-D window, usually named as multilook. The multilook processing allows reducing noise at the expenses of a resolution loss. In this letter, we analyze the influence of the multilook size while applying a polarimetric optimization of the coherence. The same optimization algorithm has been carried out with different multilook sizes and also with the nonlocal SAR filter filter, which has the advantage of preserving the original resolution of the interferogram. Our experiments have been carried out with a single pair of quad-polarimetric RADARSAT-2 images mapping the Mount Etna's volcanic eruption of May 2008. Results obtained with this particular data set show that the coherence is increased notably with respect to conventional channels when small multilook sizes are employed, especially over low-vegetated areas. Conversely, very decorrelated areas benefit from larger multilook sizes but do not exhibit an additional improvement with the polarimetric optimization.

Con el fin de conseguir valores más fiables y continuos de fase diferencial, para así facilitar la posterior interpretación de un suceso geológico en base a los modelos geofísicos disponibles, se han probado diferentes métodos de optimización basados en polarimetría para pares interferométricos de imágenes SAR. Se han empleado datos adquiridos en polarización completa mediante el satélite RADARSAT-2 y que se corresponden con la erupción volcánica del Monte Etna (Italia) en 2008. La optimización polarimétrica se ha llevado a cabo mediante una combinación de los canales polarimétricos disponibles, de modo que se explora el espacio polarimétrico para mejorar el producto final., Attending to a goal consisting in obtaining more reliable and continuous phase measurements, in order to ease the subsequent interpretation and analysis of a geological event with geophysical models, different polarimetric optimisation methods have been tested over single-pair differential SAR interferograms. Tests were carried out on data generated with two quad-polarimetric RADARSAT-2 images covering the volcanic eruption of Mount Etna (Italy) in 2008. Polarimetric optimisation has been carried out by means of a combination of the available polarimetric channels, so the available polarimetric space is searched to improve the final product.