Radar Calibration function

The Radar Calibration function corrects systematic errors in synthetic aperture radar (SAR) data and transforms radar reflectivity into radar backscatter on a reference plane.  Calibrating SAR data is required to retrieve meaningful backscatter that can be related directly to the physical properties of features in an image.

Notes

Use the Beta nought calibration method if you plan to apply terrain flattening using the Terrain Flatten raster function in your workflow. 

Use the Gamma nought calibration method if the region of interest (ROI) does not have terrain and spans over tens of kilometers. This ensures that the calibrated backscatter values are independent of the incidence angle variations. 

Only use the Sigma nought calibration method if the ROI is small and flat. 

This raster function does not calibrate the Sentinel-1 datasets with older IPE (version 2.34 or earlier) because the calibration look up table for these products may be incorrect.

Parameters

Parameter	Description
Raster	The input raster.
Calibration Type	The type of calibration to be performed. Beta nought—Calibrates the reflectivity returned to the sensor from a unit area on the slant range. This is the default. Sigma nought—Calibrates the backscatter returned to the sensor from a unit area on the ground with the plane locally tangent to the ellipsoid. Sigma nought values vary due to incidence angle, wavelength, polarization, terrain, and surface scattering properties. Gamma nought—Calibrates the backscatter returned to the sensor from a unit area aligned with the plane perpendicular to the slant range. This normalizes sigma nought using the incidence angle relative to the ellipsoid. Gamma nought values vary due to wavelength, polarization, terrain, and surface scattering properties. None—No calibration is applied.