Orbital single-pass interferometry for vessel detection and classification
Jordi J. Mallorqui(1) , Gerard Margarit(1)
, Juan M. Rius(1)
, Jesus Sanz-Marcos(1)
, and Xavier Fabregas(1)
Universitat Politecnica de Catalunya (UPC),
Carrying out an effective control of fishing activities is essential to guarantee a sustainable exploitation of sea resources. Nevertheless, as the regulated areas are extended, they are difficult and time consuming to monitor by means of traditional reconnaissance methods such as planes and patrol vessels. On the contrary, satellite-based Synthetic Aperture Radar (SAR) provides a powerful surveillance capability allowing the observation of broad expanses, independently from weather effects and from the day and night cycle. Several European projects, like IMPAST and DECLIMS, have addressed the problem of vessel detection in SAR images but there is still an open issue related with classification. The images available from current systems can be used only to perform a basic classification, for instance based on target size. Classification is an important issue in order to allow authorities to use SAR imagery as a proof of law infringement against the violators. Then, more sophisticated approaches that fulfil their requirements would require more sophisticated sensors.
This paper will analyze the usefulness of a single-pass interferometric orbital sensor with polarimetric capabilities for vessel classification purposes. The different design options regarding working frequency, resolution, baseline length and polarimetric channels will be evaluated with the POL-InSAR simulator developed at UPC. This simulator is able to generate raw data from realistic numerical models of vessels considering not only the defined characteristics of the sensor but also their movements induced by the sea state (both rotational and translational) while image is acquired. These movements can lead to important distortions on the focused images and they have to be considered when evaluating a future system for this particular application.
A basic algorithm based on Pauli decomposition, which is able to recover from interferometric data the height and polarimetric mechanism of the most important scatters of the vessel structure, will be applied to the synthetic data to show the usefulness of single-pass interferometry as well as determining the most appropriate parameters of the new sensor.