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Radiometric Analysis

Radiometric analysis can be used to assess and verify product quality globally on images with homogeneous distributed targets.

It's used to extract Radiometric Profiles from the input SAR image corresponding to azimuth blocks obtained by partitioning the whole scene.

Block-wise Radiometric Analysis

Using this algorithm the whole scene is automatically analyzed after being subdivided in azimuth blocks spanning a given amount of azimuth lines in a direction and the whole slant range axis in the other (except near and far range values removed using a margin). In case of TopSAR/ScanSAR acquisitions, bursts are used as default azimuth blocks.

Parameters Configuration

Blocks dimension can be changed using the configuration file:

azimuth_block_size: size of block in terms of azimuth lines (pixels) for acquisitions without bursts
range_pixel_margin: near/far range margin removed from axis

Once the image is partitioned, each block is analyzed and a radiometric profiles is extracted. Pre-implemented outlier removal algorithms and smoothening filters can be applied to the block values if needed using the radiometric_profiles.profile_parameters configuration sections.

Image can be provided in any radiometric quantity provided that it's specified in the configuration file if different from the default beta-nought. Output quantity can also be selected as an argument of the radiometric_profiles function.

Output data, both numeric and graphical, can be used to verify and check data properties such as: expected profiles trends with respect to incidence angle, noise magnitude and azimuth trends.

For profiles extracted along the RANGE direction, the incidence angle axis is computed using direct geocoding, while for AZIMUTH profiles a relative time axis in seconds is returned.

Few pre-configured radiometric profiles have already been developed and implemented in this module, namely:

  • Noise Equivalent Sigma-Zero (NESZ) Profiles
  • Average Elevation Profiles
  • Scalloping Profiles

These are all wrapper on the same generic radiometric profile core function with arguments and key parameters pre-set to perform that specific task.

Point-wise Radiometric Analysis

Radiometric analysis can be used to assess and verify product quality globally on images with homogeneous distributed targets.

It's used to extract Radiometric Profiles from the input SAR image corresponding to an interval of lines/samples around the selected location.