SAR SATELLITE DATA

Synthetic Aperture Radar (SAR) satellite data can come from many sensors by various providers. A provider is a government or commercial entity such as the Canadian Space Agency, European Space Agency, ICEYE, etc., who is responsible for launching the SAR satellite and then acquiring the SAR sensor data and has not modified the metadata. In ArcGIS Pro, the supported SAR sensors are currently Capella, ICEYE, RADARSAT-2, RCM, and Sentinel-1.

SAR data is commonly delivered from providers as two products:

1. Ground Range Detected (GRD) - GRD products have been averaged to produce a multilooked image projected to the ground plane using an earth ellipsoid model. A GRD image is stored as a real valued array in which the value in each pixel represents the intensity of the measured backscatter signal.
2. Single Look Complex (SLC) - SLC products are images in the image plane of the data acquisition, known as the slant plane. An SLC image is stored as a complex valued array in which the single complex value in each pixel represents the intensity and phase of the measured backscatter signal.

CHOOSING A PRODUCT

Which type of analysis you are doing will determine which of product you will need.

WORKING WITH GRD DATA Any analysis which utilizes the pixel intensity:

• Map floods
• Classify deforestation
• Chart sea ice
• Detect oil spills
• Monitor maritime activity
• Track wildfires

WORKING WITH SLC DATA Any analysis which involves interferometry ^*  which utilizes the pixel phase:

• Coherent Change Detection (CCD)
• Interferometric Synthetic Aperture Radar (InSAR)
• Digital Elevation Model (DEM) generation

 ^* interferometry - using the phase difference or interference between two signals

The  SAR products  are represented in the ArcGIS framework as SAR raster products (i.e. GRD and SLC) and contain raster product templates (i.e. beam mode). This allows you to add SAR data to your map directly from the original dataset, without the need for additional import or conversion tools. A raster product can have one or multiple raster product templates associated with them. Adding a raster product directly will add the default template.

SAR data is added to a mosaic dataset using SAR raster types. In ArcGIS Pro, currently the supported  SAR raster types  are:

•  Capella 
•  ICEYE 
•  RADARSAT-2 
•  RADARSAT Constellation Mission (RCM) 
•  Sentinel-1 

Learn how to use  SAR raster types  to add a GRD  SAR raster product  from the following  supported SAR sensors :  Capella ,  ICEYE ,  RADARSAT-2 ,  RCM , and  Sentinel-1  to your ArcGIS Pro map.

Once the SAR data has been added to your map you can begin working with your scenes. ArcGIS Pro offers  geoprocessing tools  to process and analyze SAR data.

With the  Image Analyst license , users can access ArcGIS Pro tools that support SAR data from various satellite sensors.

 Geoprocessing  is a framework and set of tools for processing geographic and related data. The comprehensive suite of geoprocessing tools can be used to perform analysis or manage GIS data in an automated way. A tool can be opened and ran from the  Geoprocessing pane . You can also use any tool in  ModelBuilder  or call it from a  Python script .

SAR PROCESSING

ArcGIS Pro offers powerful  SAR geoprocessing tools  to process SAR data in the SAR Toolset. This processing is needed to prepare the SAR data to ensure that it is accurate and properly located so that it can be ready for analysis and interpretation. With the  Image Analyst license , users can access ArcGIS Pro tools that support SAR data from various satellite sensors.

1.  Apply Geometric Terrain Correction  Orthorectifies the input SAR data using a range-Doppler backgeocoding algorithm.
2.  Apply Orbit Correction  Updates the orbital information in the SAR dataset using a more accurate orbit state vector (OSV) file.
3.  Apply Radiometric Calibration  Converts the input SAR reflectivity into physical units of normalized backscatter by normalizing the reflectivity using a reference plane.
4.  Apply Radiometric Terrain Flattening  Corrects the input SAR data for radiometric distortions due to topography.
5.  Convert SAR Units  Converts the scaling of the input SAR data between amplitude and intensity and between linear and decibels (dB).
6.  Create Color Composite  Creates a three-band raster dataset from a multiband raster dataset.
7.  Despeckle  Corrects the input SAR data for speckle, which is a result of coherent illumination that resembles a grainy or salt and pepper effect.
8.  Download Orbit File  Downloads the updated orbit files for the input SAR data.
9.  Remove Thermal Noise  Corrects backscatter disturbances caused by thermal noise in the input SAR data, resulting in a more seamless image.

Esri Radio Detection and Ranging (RADAR) Specialists