ASF ArcGIS Desktop SAR Toolbox
ASF has developed an ArcGIS Desktop Toolbox containing tools that perform geoprocessing tasks useful for working with Synthetic Aperture Radar (SAR) data. The tools were designed to be used with Radiometric Terrain Corrected (RTC) SAR datasets, but several of the tools have the potential to be used with a variety of rasters, including non-SAR datasets. The Toolbox is distributed as a zipped archive including the .pyt Toolbox script and associated .xml files. There is an XML file for the toolbox itself and one for each of the tools it contains. These XML files are accessed when a user views the Item Description for the toolbox or any of its constituent tools in the ArcMap Catalog window. The information can also be found in the Description tab in ArcCatalog, and portions of the xml contents are displayed as appropriate in the tool dialog box when a tool is launched in ArcMap. These XML files must be kept in the same directory as the Python Toolbox (.pyt) file, or the information they contain will no longer be accessible to ArcGIS.
The Toolbox currently contains the following Tools:
- Unzip Files Tool: assists in file management when downloading .zip files from ASF. This tool could be used to extract to a specified location any zip files with an additional internal directory containing the individual files. The tool deletes the original zip files once they are extracted, and is especially helpful when dealing with filenames that are so long that they are beyond the maximum allowed in default Windows unzip utilities.
- Scale Conversion Tool: allows easy conversion of pixel values in calibrated SAR datasets (such as RTC rasters) from power or amplitude scale into power, amplitude or dB scale. This is an application specific to SAR data values.
- Reclassify RTC Tool: generates a raster that includes only those pixels below a user-defined threshold value, and is designed for identifying water pixels. This tool could be used for any application where the user is interested in identifying values below a given threshold.
- Log Difference Tool: compares two rasters by calculating the log difference on a pixel-by-pixel bases to identify areas where backscatter values have changed over time. This tool could be used to compare the pixel values of any two single-band rasters; it is not specific to SAR data.
- Users must have ArcGIS Desktop (ArcMap) installed and licensed on their computer. The Toolbox has been tested with versions 10.6.1 and 10.7.1, but may work with earlier versions.
- Note that several of the tools require the Spatial Analyst extension. Users who do not have licensing for this extension in ArcGIS will not be able to use many of the included tools.
To install the Toolbox:
- Download the zip file, and extract the contents to any directory accessible by the computer running ArcGIS.
- Ensure you have access to the Spatial Analyst Extension in ArcMap.
- Click on the Customize menu in ArcMap and select Extensions…. Check the box next to Spatial Analyst and click the Close button at the bottom of the Extensions window. If you are unable to check this box, you do not have access to the Spatial Analyst extension and will not be able to make use of tools requiring this extension.
To use the Toolbox:
- In the ArcMap Catalog window, navigate to the directory containing the toolbox (create a new folder connection if necessary).
- To open the Catalog window, click on the Windows menu in ArcMap and select Catalog.
- Note that if you explore the extracted contents outside of the ArcGIS environment, the directory will contain one .pyt file and a number of .xml files. In the ArcMap Catalog window, only the Toolbox is displayed, and when it is expanded, each of the Tools contained in the Toolbox script is displayed. The XML files are automatically referenced when ArcGIS requires the information they contain, and do not appear as additional files in the ArcMap Catalog environment. The XML files must remain in the same directory as the .pyt file, and their filenames should not be changed.
- Double-click the ASF_Tools.pyt file to display the Tools (Scripts) included in the toolbox.
- Double-click on a Tool (displayed with a Script icon) to launch the dialog box, as you would for any other ArcGIS Tool/Script.
- Click on the Show Help button at the bottom of the tool window to see more information about the tool and helpful tips specific to each parameter.
- Click on the Tool Help button at the bottom of the Help pane to open another window that displays most of the contents of the tool’s Item Description.
- Enter the parameters as prompted and click the OK button to execute the tool.
- Note that output products are not automatically added to a project by default. You must navigate to them in the Catalog window (or using the Add Data dialog) and add them to your project if desired.