There are many potential usage patterns for NISAR data, from SAR scientists downloading RRSD products to perform complex processing workflows to disaster response teams viewing GCOV products in GIS platforms. There are a range of tools and resources available for accessing, processing, analyzing and visualizing NISAR products to support this range of use cases.
Accessing NISAR Data¶
NISAR data can be accessed from cloud storage, either by downloading or using cloud computing approaches to work with the data directly in the cloud. There are map-based user interfaces and programmatic solutions for finding and accessing NISAR data. Refer to Accessing NISAR Data for more information.
Processing Software¶
The processing algorithms used for the NISAR Mission are included in ISCE3, the third iteration of the InSAR Scientific Computing Environment (ISCE). ISCE3 is an open source library for processing spaceborne and airborne Interferometric Synthetic Aperture Radar (InSAR) data, and development is currently funded through the NISAR project.
The NISAR Mission is using ISCE3 functionality to generate the products that are archived by ASF. This software package is also publicly available for users who want to script their own processing workflows, but this requires scientific programming expertise and an understanding of the principles of SAR acquisitions.
GIS Software¶
The NISAR mission generates a number of Level 2 and 3 products, which are projected to map coordinates and are suitable for use in GIS workflows. Any of the gridded variables in the Level 2 and 3 products can be added to ArcGIS Pro or QGIS. The amplitude component of the SAR dataset is particularly well-suited to GIS analysis, as it presents an image of the Earth’s surface.
Amplitude Products¶
Radar backscatter values can be extracted from either Geocoded Covariance (GCOV) or Geocoded Single Look Complex (GSLC) products. Refer to Amplitude Datasets to learn more about the differences and determine which product may be better suited for your workflow.
If you are new to NISAR data and want to explore what amplitude data looks like, the GCOV products are more straightforward to use in GIS than the GSLCs.
Coherence¶
Among the non-amplitude datasets, the Coherence layers from the Geocoded Unwrapped Interferogram (GUNW) products may be of interest to GIS users. Coherence represents the correlation of phase measurements from one SAR acquisition to the next, which can also indicate areas that have undergone changes in surface structure.
The pixel values of a Coherence layer range from 0 to 1. Low coherence values often indicate areas that have undergone disturbance, while high coherence values tend to indicate areas with more stable conditions.
Soil Moisture¶
The Soil Moisture (SME2) products are the only Level 3 NISAR products generated by the mission. SME2 products contain several soil moisture layers generated using different approaches, all of which are easily added to GIS projects.
File Size and Format¶
NISAR files are very large, and it can take a long time to load them into GIS projects. If your area of interest is smaller than the full extent of the product, you may want to consider subsetting the data before using them for analysis workflows. This is particularly important if you choose to work with GSLC products.
The HDF5 data format of the NISAR products may be unfamiliar to some users, but there are workflows for adding NISAR layers to GIS projects and performing analysis leveraging existing raster analysis tools.
Guidance¶
Refer to Using NISAR Data in ArcGIS to learn how to work with NISAR data in ArcGIS Pro and Using NISAR Data in QGIS for guidance on using NISAR data in QGIS.
Programmatic Approaches¶
Users who want to develop programmatic workflows to access, analyze, and visualize NISAR data can use a range of existing open-source software packages. Functions from packages specifically designed for working with SAR data can be combined with functions from more general packages for working with raster and array data to accomplish a range of analyses and visualizations.
Refer to the Tutorials section for more information and available workflows.