Overview

We have explained in earlier chapters how a SAR system works and how data directly related to local ground reflectivity can be obtained by processing the signals received by a monostatic antenna. This analysis helped us assess the resolution limits of such systems: whether or not we are able to distinguish between returns from two objects lying close to each other on the ground depends on several well determined physical parameters (antenna dimensions, platform speed, and type of the transmitted wave in terms of frequency and pulse duration).

This chapter is devoted to the images that will be used in this book and on which several types of processing will be assessed. In terms of their degree of preprocessing, images fall into several categories:

• raw data that are in fact two-dimensional data prior to their SAR processing (level 0);

• single-look complex data resulting from raw data 2-D processing: pulse compression and synthetic aperture algorithm (level 1); and

• amplitude image data that is generally multi-look (levels 2 and 3).

We will examine the problem linked to the calibration of such data and the possibility of obtaining data at regular intervals considering the geographic location of the studied region and the operating requirements imposed by satellite tracking.

Polarimetric data will be addressed separately in section 4.1.5.

^[1]

4.1 Image Data

Space agencies and satellite image providers usually supply data in the traditional CEOS format. The Committee...