Synthetic aperture radar FAQ

Available with Image Analyst license.

Answers to common questions about synthetic aperture radar (SAR) are provided.

• Do I need to download the SAR sensor data?

• Why do I get the error messages Failed to add data or Failed to open data?

• Is the Download Orbit File tool used for all supported sensors to obtain the orbit state vectors (OSV) file?

• Does the DEM need to cover the exact size of the SAR data?

• Why is my SAR data not aligned with my basemap?

• How do I check what SAR processing has been applied to my SAR dataset?

• What is the difference between the SAR geoprocessing toolset and the SAR raster functions?

Do I need to download the SAR sensor data?

Yes. Once the Level 1 SAR data is downloaded, it can be processed into analysis-ready data (ARD) using the SAR processing workflow.

Why do I get the error messages Failed to add data or Failed to open data?

These message can occur if the path name length is too long. ArcGIS Pro supports file system path names with a maximum path length of 260 characters.

Is the Download Orbit File tool used for all supported sensors to obtain the orbit state vectors (OSV) file?

The Download Orbit File tool currently only supports Sentinel-1 sensors, since more precise OSVs are updated and provided separately from the SAR data. For more information, see Download and apply orbit state vectors. For other supported SAR sensors, data is provided with OSVs in the metadata.

Does the DEM need to cover the exact size of the SAR data?

The digital elevation model (DEM) that is used to process SAR data must be in the WGS84 (EPSG:4326) geographic coordinate system. It is recommended that it have a resolution similar to or better than the input SAR data. A DEM can be retrieved from external sites such as OpenTopography.

The DEM should cover the extent of the SAR data. When using the Apply Radiometric Terrain Flattening tool, the input DEM does not need to span the entire SAR dataset; the tool will output NoData values for the pixels outside of the DEM extent.

For applications in which no terrain is present, you can omit the input DEM.

Why is my SAR data not aligned with my basemap?

Some SAR data is not orthorectified. Supported data that is not orthorectified includes Sentinel-1 GRD, ICEYE GRD, and RADARSAT Constellation Mission (RCM) GRD. An essential step in preparing SAR data for analysis is running the Apply Geometric Terrain Correction tool, which uses the range-Doppler approach to properly orthorectify the data.

How do I check what SAR processing has been applied to my SAR dataset?

The processing history for a SAR dataset can be accessed from the Layer Properties dialog box. To access it, in the Contents pane, right-click the radar layer and click Properties. In the Layer Properties dialog box, click the Source tab and expand Processing Histroy.

What is the difference between the SAR geoprocessing toolset and the SAR raster functions?

Raster functions are operations that perform on-the-fly processing directly to the pixels of a raster layer in the map; the geoprocessing tools write out new raster datasets to disk. The Synthetic Aperture Radar toolset contains tools that perform the complete ARD workflow.