Elvey building on the UAF campus is home to the Geophysical Institute

Contact Us

The Alaska Satellite Facility is located on the Troth Yeddha’ campus of the University of Alaska Fairbanks and is a part of the Geophysical Institute . ASF offices and ground station operations are located in the CT Elvey and West Ridge Research Buildings.

Business Hours

Monday – Friday
8:00 AM – 5:00 PM Alaska Time (AKST UTC-8; AKDT UTC-9)

User Support Office

Elvey building on the UAF campus is home to the Geophysical Institute

Address

Alaska Satellite Facility
Geophysical Institute
University of Alaska Fairbanks
2156 Koyukuk Drive
Fairbanks, AK 99775 USA

Interferogram of Okmok Island.

SAR FAQ

Common questions and answers about Synthetic Aperture Radar

Unlike the aperture in a camera, which opens to let in light, radar aperture is another term for the antenna on the spacecraft or aircraft. The radar antenna first transmits electromagnetic energy toward Earth and then receives the returning energy after it reflects off of objects on the planet. In the NASA image below, the radar antenna is the rectangle at the Earth end of the 1978 Seasat satellite. The data collected by the radar antenna are then transmitted to another kind of antenna on Earth — such as the antennas of the ASF Satellite Tracking Ground Station — so they can be stored and processed.

In general, the larger the antenna, the more unique information scientists can obtain about an object — and the more information, the better the image resolution. However, antennas in space are not large. So scientists use the spacecraft’s motion, along with advanced signal-processing techniques, to simulate a larger antenna.

Synthetic aperture radar (SAR) interferometry (InSAR) detects motion or elevation by comparing radar signals from two or more images of the same scene. The images are taken at different times from the same vantage point in space. SAR interferometry is often used to detect surface changes (for use in seismology, for example) or to generate digital elevation maps. The InSAR image below shows deformation on Okmok, a volcano in the Aleutian Islands. 

Interferogram of Okmok Island.
Image courtesy of Zhong Lu, © ESA 2008

Because the radar wavelength is longer than particles in a cloud, such as droplets, the signal traveling through a cloud is mostly unaffected by any refraction at the boundaries of the different media.

In microwave remote sensing, scientists measure the time and magnitude of the signal backscattered from the ground to the radar antenna. The magnitude of the signal defines the brightness of a given pixel in the image. The resulting image has a grayscale. Scientists sometimes colorize SAR images to highlight certain data or features.

The interpretation of synthetic aperture radar (SAR) images is not straightforward. The reasons include the non-intuitive, side-looking geometry. Here are some general rules of thumb:

  • Regions of calm water and other smooth surfaces appear black (the incident radar reflects away from the spacecraft).
  • Rough surfaces appear brighter, as they reflect the radar in all directions, and more of the energy is scattered back to the antenna. Rough surface backscatter even more brightly when it is wet.
  • Any slopes lead to geometric distortions. Steeper angles lead to more extreme layover, in which the signals from the tops of mountains or other tall objects “layover” on top of other signals, effectively creating foreshortening. Mountaintops always appear to tip towards the sensor.
  • Layover is highlighted by bright pixel values. The various combinations of the polarization for the transmitted and received signals have a large impact on the backscattering of the signal. The right choice of polarization can help emphasize particular topographic features.
  • In urban areas, it is at times challenging to determine the orbit direction. All buildings that are perfectly perpendicularly aligned to the flight direction show very bright returns.
  • Surface variations near the size of the radar’s wavelength cause strong backscattering. If the wavelength is a few centimeters long, dirt clods and leaves might backscatter brightly.
  • A longer wavelength would be more likely to scatter off boulders than dirt clods, or tree trunks rather than leaves.
  • Wind-roughened water can backscatter brightly when the resulting waves are close in size to the incident radar’s wavelength.
  • Hills and other large-scale surface variations tend to appear bright on one side and dim on the other. (The side that appears bright was facing the SAR.)
  • Due to the reflectivity and angular structure of buildings, bridges, and other human-made objects, these targets tend to behave as corner reflectors and show up as bright spots in a SAR image. A particularly strong response — for example, from a corner reflector or ASF’s receiving antenna — can look like a bright cross in a processed SAR image.

In ASF’s full-resolution synthetic aperture radar (SAR) images, objects can be distinguished as small as about 30 meters wide. Some of the smaller items scientists have spotted have been ships and their wakes. When the synthetic aperture radar (SAR) happens to be aligned at a certain angle, long thin objects such as roads or even the Alaskan oil pipeline can also be seen. Objects can be much smaller than the resolution and still be observable such as bright point objects. They only need to be perfectly aligned with the look direction of the synthetic aperture radar (SAR) sensor.

As the spacecraft moves along in its orbit, the radar antenna transmits pulses very rapidly in order to obtain many backscattered radar responses from a particular object. The synthetic aperture radar (SAR) processor could use all of these responses to obtain the object’s radar cross-section (how brightly the object backscattered the incoming radar), but the result often contains quite a bit of speckle. Generally considered to be noise, speckle can be caused by an object that is a very strong reflector at a particular alignment between itself and the spacecraft, or by the combined effect of various responses all within one grid cell. To reduce speckle, the data are sometimes processed in sections that are later combined — called looks. The more looks used to process an image, the less speckle. However, resolution is reduced, and information is lost in this process. Several research groups are developing/improving algorithms to reduce speckle while saving as much accurate information as possible.

Noise is defined as random or regular interfering effects that degrade the data’s information-bearing quality. Speckle is a scattering phenomenon that arises because the resolution of the sensor is not sufficient to resolve individual scatterers. Physically speaking, speckle is not noise, as the same imaging configuration leads to the identical speckle pattern. Speckle is removed by multi-looking. See “What is a ‘look'” above.

After the radar sends its microwave signal toward a target, the target reflects part of the signal back to the radar antenna. That reflection is called backscatter. Various properties of the target affect how much it backscatters the signal.

  • Sentinel-1
  • PALSAR (Faraday rotation can be a factor.)
  • RADARSAT-1 (The most suitable RADARSAT-1 data for InSAR were acquired during and after the Modified Antarctic Mapping Mission in the fall of 2000.)
  • ERS-1
  • ERS-2
  • JERS-1

IfSAR is another term for InSAR. InSAR is the more common term, particularly for satellite-borne sensors. IfSAR has been used more by the military and/or for airborne sensors.

Layover is a type of distortion in a synthetic aperture radar (SAR) image. The radar is pointed to the side (side-looking) for imaging. Radar signals that return to the spacecraft from a mountaintop arrive earlier or at the same time as the signal from the foot of the mountain, seeming to indicate that the mountaintop and the foot of the mountain are in nearly the same place, or the mountaintop may also appear “before” the foot. In a synthetic aperture radar (SAR) image with layover, the mountains look as if they have “fallen over” towards the sensor.

Where features are shifted from their actual location, the resulting geolocations are incorrect. This effect can be removed by the technique of terrain correction (also see “What is terrain correction?” below).

As with shadows from sunlight, shadows in synthetic aperture radar (SAR) images appear behind vertical objects. Mountains may appear to have black shadows behind them, depending on the steepness of the slope. The shadows appear black because no radar signals return from there.

Radiometric correction involves removing the misleading influence of topography on backscatter values. For example, the correction eliminates bright backscatter from a steep slope, leaving only the backscatter that reveals surface characteristics such as vegetation and soil moisture.

Animation showing the effect of radiometric correction.
ASF DAAC 2014; © JAXA/METI 2008

Terrain correction is the process of correcting geometric distortions that lead to geolocation errors. The distortions are induced by side-looking (rather than straight-down looking or nadir) imaging, and compounded by rugged terrain. Terrain correction moves image pixels into the proper spatial relationship with each other. Mountains that look as if they have “fallen over” towards the sensor are corrected in their shape and geolocation.

Comparison showing the effect of terrain correctio.
ASF DAAC 2014; © JAXA/METI 2008.

Most digital elevation models (DEM) are geoid-based and require a correction before they can be used for terrain correction. The DEM included in an ASF radiometrically terrain corrected (RTC) product file was converted from source DEM orthometric height to ellipsoid height using the ASF MapReady geoid_adjust tool. This tool applies a geoid correction so that the resulting DEM relates to the ellipsoid.

An online tool is available that computes the height of the geoid above the WGS84 ellipsoid, and will show the amount of correction that was applied to the source DEM used in creating an RTC product.
Comparison of DEM heights.

Orthorectification corrects geometric distortions in imagery, just as terrain correction does (see “What is terrain correction?” above). The term ‘orthorectification’ is used more often in association with aerial and optical imagery. Terrain correction generally refers to synthetic aperture radar (SAR) imagery.

A georeferenced image has the location of the four corners of the image and the information needed to put the data into a projection. Geocoded data is already projected. Each point in the image is associated with a geographic coordinate.

  • C-band (~5.3 GHz)
    Applies to ERS-1, ERS-2, RADARSAT-1, Sentinel-1
    – Variety of applications, but particularly sea ice, ocean winds, glaciers
  • L-band (~1.2 GHz)
    Applies to PALSAR, UAVSAR, AIRSAR, JERS-1, Seasat
    – Provides vegetation penetration
    – Applications included sea ice, tropical forest mapping, soil moisture
    – Subject to ionospheric effects
  • P-band (~0.4 GHz)
    Applies to some products of UAVSAR
    – Greatest penetration depth through vegetation and into soil
    – Ideal for soil moisture and biomass
    – Difficult to operate from space due to ionospheric effects

SAR backscatter

Fundamentals of SAR – Media Resources

SAR Data and GIS

Types of Synthetic Aperture Radar (SAR) Products at ASF

ASF product types and processing levels

Processing TypeProcessing LevelImage TypeProduct DescriptionOpen-source softwareCommercial software
Raw DataL0, L1.0, RAWUnfocusedUnprocessed signal data. Requires a SAR processor to be visualized.ISCEENVI SARscape
GAMMA
Single Look Complex (SLC)L1.1, SLCFocused (single look); has speckleContains amplitude and phase values. Retains slant-range geometry.ASF HyP3
Sentinel-1 Toolbox
PolSARpro
ENVI SARscape
GAMMA
AmplitudeL1, L1.5, GRD (Ground Range Detected)Focused (multilooked); reduced speckleCan be visualized. Contains amplitude values only. Retains slant-range geometry. Projected to ground range coordinates.ASF HyP3
Sentinel-1 Toolbox
ASF MapReady
ENVI SARscape
GAMMA
Corrected amplitudeGeoTIFFGIS-compatibleImage has had georeferencing applied.QGISArcGIS
Corrected amplitudeRadiometric Terrain Correction (RTC)GIS-compatibleImage has had radiometric and terrain correction applied.QGISArcGIS

ASF Datasets – Formats and Files

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    ALOS PALSAR

    FormatProduct NameProduct FilesProcessing LevelOpen-source ToolsCan Be Used For
    CEOSL1.0LED, IMG, VOL, TRLRawN/AProduction of higher-level products
    CEOSL1.1LED, IMG, VOL, TRLSingle Look ComplexSentinel-1 Toolbox, PolSARproInterferometry
    CEOSL1.5LED, IMG, VOL, TRLAmplitude imageMapReady, ASFView (part of MapReady), Sentinel-1 Toolbox, PolSARproVisualization

    ALOS PALSAR RTC

    FormatProduct NameProduct FilesProcessing LevelOpen-source ToolsCan Be Used For
    GeoTIFFHi-Res Terrain Correctedtif, jpg, xml, kmz, wldGeocoded AmplitudeQGIS, Graphics viewing softwareVisualization; GIS-compatible
    Low-Res Terrain Corrected

    Sentinel-1

    FormatProduct NameProduct FilesProcessing LevelOpen-source ToolsCan Be Used For
    SAFEL0tif, xml, xsd, kml, html, png, pdf, safeRawN/AProduction of higher-level products
    GeoTIFFL1 SLCSLCASF HyP3, Sentinel-1 Toolbox, PolSARproInterferometry
    L1 Detected High-Res Dual-PolL1 Georeferenced AmplitudeASF HyP3, Sentinel-1 ToolboxVisualization
    L1 Detected High-Res Single-PolASF HyP3, Sentinel-1 Toolbox
    L1 Detected Mid-Res Dual-PolASF HyP3, Sentinel-1 Toolbox, PolSARpro
    L1 Detected Mid-Res Single-PolASF HyP3, Sentinel-1 Toolbox
    NetCDFOCNnc, xsd , kml , html, png, pdf, safeL2Sentinel-1 Toolbox, PanoplyPolSARproOcean wind, wave and currents

    UAVSAR PolSAR

    FormatProduct NameProduct FilesProcessing LevelOpen-source ToolsCan Be Used For
    UAVSARGround Projected Complexgrd, annGeoreferenced AmplitudeMapReady, PolSARproVisualization
    Multi-Look Complexmic, annMLCPolarimetry
    Ground Projected Complex, 3X3grd, annGeoreferenced AmplitudeVisualization
    Ground Projected Complex, 5X5Visualization
    Compressed Stokes Matrixdat, annAIRSAR compressed stokes matrixPolarimetry
    GeoTIFFPauli DecompositiontifMLC polarimetric decompositionQGIS; graphics viewing softwareVisualization; GIS compatible
    GeoTIFF HeightDEMQGISDEM
    KMZGoogle Earth KMZkmzKML compressedGoogle EarthVisualization

    UAVSAR RPI

    FormatProduct NameProduct FilesProcessing LevelOpen-source ToolsCan Be Used For
    UAVSARAmplitudeamp1, amp2, annAmplitudeMapReady, PolSARproVisualization
    Ground Projected Amplitudeamp1.grd, amp2.grd, hgt.grd, annGeoreferenced Amplitude
    Interferogramint, unw, cor, annInterferogram
    Ground Projected Interferogramcor.grd, hgt.grd, int.grd, unw.grd, ann
    KMZGoogle Earth KMZamp1.kmz, amp2.kmz, cor.kmz, hgt.kmz, int.kmz, osr.kmz, unw.kmzGoogle Earth

    AIRSAR TOPSAR

    FormatProduct NameProduct FilesOpen-source ToolsCan Be Used For
    AIRSARC-band DEM and Compressed Stokes Matrixc.corgr, c.demi2, c.vvi2MapReady, PolSARproPolarimetry
    L-band Compressed Stokes Matrixl.datgr
    P-band Compressed Stokes Matrixp.datgrPolSARpro

    AIRSAR PolSAR - AIRSAR ATI (Experimental)

    FormatProduct NameProduct FilesProcessing LevelOpen-source ToolsCan Be Used For
    AIRSAR3-Frequency Polarimetryc.dat, l.dat, p.datCompressed stokes matrixMapReady, PolSARproPolarimetry
    JPGAlong-Track Interferometry*intf*, *uwScc*, *az*, *uwWrp*, *uwWcc*, *uwWrp, *par, *pppSLC, MLCN/AOcean current velocity measurement

    ERS-1, ERS-2, JERS-1, RADARSAT-1

    FormatProduct NameProduct FilesProcessing LevelOpen-source ToolsCan Be Used For
    CEOSL0D, L, P, kml, jpgRawN/AProduction of higher-level products
    L1AmplitudeMapReady, ASF View (part of MapReady), Sentinel-1 ToolboxVisualization

    Seasat

    FormatProduct NameProduct FilesProcessing LevelOpen-source ToolsCan Be Used For
    HDF5L1 HDF5h5, xml , kml , jpg, qc_reportAmplitudeMapReady, QGISVisualization; GIS-compatible
    GeoTIFFL1 GeoTIFFtif, xml, kml, jpg, qc_reportGeocoded amplitudeQGIS; graphics viewing software

    SMAP

    FormatProduct NameProduct FilesProcessing LevelOpen-source ToolsCan Be Used For
    HDF5L1A Radarh5, xmlL1AN/AProduction of higher-level products
    L1A Radar Receive Only (experimental)Passive radiometry
    L1B S0 LoResL1BPanoply, HDFViewSoil moisture / freeze-thaw state mapping
    L1C S0 HiResL1C

    Datasets Available from ASF DAAC

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      Unrestricted SAR Datasets

      These data are freely available and may be downloaded by anybody with an Earthdata Login username and password.

      Dataset NameSensor PlatformMission DatesFind DataUsage ExamplesSpatial Coverage
      ALOS PALSARSatellite2006 - 2011Vertex Data SearchASF Search APIBroad applications: glaciers, landslides, volcanoes, earthquakes, oil seeps, wetlands, sea ice, and more.The Americas, Antarctica, select wordwide sites
      SAR Sensor: L-band
      Repeat Cycle: 46 days
      Products: L1.0 raw, L1.1 single look complex (SLC), L1.5 Georeferenced amplitude image, Hi-res RTC image, Low-res RTC image
      Sentinel-1Satellite2014 - PresentVertex Data SearchASF Search APIBroad applications: volcanoes, earthquakes, glaciers, land subsidence, sea ice, flooding, oceans, and moreGlobal
      SAR Sensor: C-band
      Repeat Cycle: 12 days
      Products: L0 raw, L1 single look complex (SLC), L1 ground-range detected mid-res single-pol (GRD-MS), L1 ground-range detected high-res single-pol (GRD-HS), L1 ground-range detected mid-res dual-pol (GRD-MD), L1 ground-range detected high-res dual-pol (GRD-HD), L2 ocean (OCN)
      UAVSARAircraft2008 - PresentVertex Data SearchASF Search APISelect locations: oil spills, earthquakes, volcanoes, oceans, land cover, and moreTargeted worldwide sites
      SAR Sensor: L-band
      Repeat Cycle: Non-applicable
      Products: Single look complex (SLC), multi-look complex cross products, compress stokes matrix, ground-projected calibrated cross products, DEM
      ERS-1Satellite1991 - 1997Vertex Data SearchASF Search APIPolar regions and processes (sea ice, Arctic, Antarctic)Primarily polar, within station masks of the ASF and McMurdo ground stations
      SAR Sensor: C-band
      Repeat Cycle: 35 days
      Products: L0 raw, L1 amplitude image
      ERS-2Satellite1995 - 2011Vertex Data SearchASF Search APIPolar regions and processes (sea ice, Arctic, Antarctic)Primarily polar, within station masks of the ASF and McMurdo ground stations
      SAR Sensor: C-band
      Repeat Cycle: 35 days
      Products: L0 raw, L1 amplitude image
      AIRSARAircraft1990 - 2004Vertex Data SearchASF Search APISelect locations: oceans, coasts, forest ecology, geology, hydrology, earthquakes, archeaology, and moreSelected sites worldwide
      SAR Sensor: L-band, P-band, C-band
      Repeat Cycle: Non-applicable
      Products: Along-track interferometry, 3-frequency polarimetry, L-Band compressed stokes matrix, P-Band compressed stokes matrix, C-Band DEM and compressed stokes matrix
      SeasatSatellite1978Vertex Data SearchASF Search APIPortions of northern oceans and land (the first NASA SAR mission; data processed by ASF in 2013)Regions of Northern Hemisphere, including oceans and N. America
      SAR Sensor: L-band
      Repeat Cycle: 3 days at launch; 17 days after mid-August
      Products: L1 image, GeoTIFF
      SMAPSatellite2015 (3 months)Vertex Data SearchASF Search APISoil moisture and freeze/thaw state (detailed data from 3 months in 2015). Benchmark data for flood, landslide, and drought monitoring; agricultural planning; and climate forecastingGlobal
      SAR Sensor: L-band
      Repeat Cycle: 3 days
      Products: L1A_Radar, L1B_S0_LoRes, L1C_S0_HiRes, L1A receive only

      Restricted SAR Datasets

      Permission to access and download these data requires that a user meet the following conditions:

      • The data will be used for non-commercial, research purposes only
      • The user is currently living in the United States

      A Restricted Data Use Request form must be submitted.

      Dataset NameSensor PlatformMission DatesFind DataUsage ExamplesSpatial Coverage
      JERS-1Satellite1992 - 1988Vertex Data SearchASF Search APIImportant forests of the world: Southeast Asia, Africa, Central America, South America (Amazon Basin), and boreal North America.Global
      SAR Sensor: L-band
      Repeat Cycle: 44 days
      Products: L0 raw, L1 amplitude image
      RADARSAT-1Satellite1995 - 2008Vertex Data SearchASF Search APIArctic sea ice and other broad applications: volcanoes, ocean winds, ecology, soil moisture, wetlands, flooding, and more.Global
      SAR Sensor: C-band
      Repeat Cycle: 24 days
      Products: L0 raw, L1 amplitude image

      Derived SAR Datasets

      These higher-level datasets were created using ASF SAR data.

      Dataset NameSensor PlatformMission DatesFind DataUsage ExamplesSpatial Coverage
      RAMP
      RADARSAT-1 Antarctic Mapping Mission
      Satellite1997 and 2000ASF WebsiteHistoric, high-resolution map of Antarctica: ice-sheet morphology, rock outcrops, research infrastructure, coastline, and more.Antarctica
      SAR Sensor: C-band
      Products: Tiles, mosaics
      Post-RAMP Antarctic MosaicsSatellite2004 and 2007ASF WebsiteAntarctic ice sheets (emphasis on velocities): Drygalsky Ice Tongue (David Glacier), Thwaites Glacier, and Pine Island Glacier.Select Antarctic ice sheets
      SAR Sensor: C-band
      Products: SAR mosaics, glacier velocity files
      Sea Ice MEaSUREsSatellite1995 - 2012ASF WebsiteArctic Ocean sea ice motion with three-day radar snapshots as the ice goes through dramatic changes over 11 years.Arctic Ocean
      SAR Sensor: C-band
      Products: Lagrangian, 3-day gridded, and Eularian data files
      Terrestrial EcologySatellite2007 - 2010ASF WebsiteEcological research.Select sites in Western Hemisphere
      SAR Sensor: L-band
      Products: GeoTIFFimetric images
      Wetlands MEaSUREsSatellite1993 - 2009ASF WebsiteWetlands ecology, including their role in climate, biogeochemistry, hydrology, and biodiversity.Amazon, Alaska, the Americas, global (coarse resolution)
      SAR Sensor: L-band
      Products: Fine-resolution, 100-meter maps of wetland extent, vegetation type, and seasonal inundation dynamics for continental-scale areas covering crucial wetland regions; global, 10-day mappings of inundation extent at ~25-km resolution; interactive time-series tool and time-series animation; GeoTIFF

      Optical Datasets

      These data are freely available and may be downloaded by anybody with an Earthdata Login username and password.

      Dataset NameSensor PlatformMission DatesFind DataUsage ExamplesSpatial Coverage
      ALOS AVNIR-2 ORISatellite2006-2011Vertex Data SearchASF Search APISpatial coverage maps for land and coastal zones; monitoring regional environmentsGlobal
      Sensor: Visible and Near-Infrared Radiometer
      Repeat Cycle: 46 days
      Products: 1B1 Ortho Rectified Image
      Image of the Earthdata website Login registration screen.

      Get an Account. Find Data.

      Step 1: Get an Earthdata Login Account

      A NASA Earthdata Login account is required for downloading data and tools from ASF. Registering for an account is free and may be done at the Earthdata Login registration site link below.

      Please note that the registration and EULA agreement process must be completed in English.

      Step 2: Find Data

      An Earthdata Login username and password are required to download ASF data using Vertex Data Search and ASF Search API, or to download ASF Tools and Derived Datasets from the website.

        • All of the datasets and tools at ASF are free, and most are available to download without restriction.
        • Only the JERS-1 and RADARSAT-1 datasets are restricted. Access to these data requires the submission of a data access request form.

      Data Search Tools

      • Vertex Data Search is an easy-to-use, yet powerful interface for searching the ASF data archive. Search areas can be created by drawing on a map, entering coordinates, or importing a geospatial file. Searches can be done on a list of file names or by campaign. Filters can be applied to refine a search. And search results can be downloaded individually or in bulk.
      Screenshot of Vertex interface.
      • ASF Search API is a programmatic method of searching the ASF data archive from a browser window or command line interface. Search results can be saved and downloaded using Wget, cURL, or aria2.
      Screenshot of cammand line interface of the ASF Search API.
      • NASA Earthdata Search is a search interface that provides the ability to search all NASA Earth observation data holdings.
      Image of the NASA Earthdata search interface.

      Third-Party Software Tools

      Free/Open-Source Tools

      ERDAS ER Viewer — The ERDAS ER Viewer is an easy-to-use image viewer featuring interactive roaming and zooming with very large JPEG 2000 and ECW files.

      GMT5SAR — GMTSAR is an open source (GNU General Public License) InSAR processing system designed for users familiar with Generic Mapping Tools (GMT).

      InSAR ISCE — InSAR Scientific Computing Environment is a flexible and extensible computing environment for geodetic image processing for Synthetic Aperture Radar (SAR), available to WInSAR members.

      LIZARDTECH GeoViewer — Display MrSID imagery, raster imagery, LiDAR point clouds, and vector overlays in one standalone application.

      PolSARPro — The Polarimetric SAR Data Processing and Educational Tool aims to facilitate the accessibility and exploitation of multi-polarized synthetic aperture radar (SAR) datasets.

      pyroSAR — A Python Framework for Large-Scale SAR Satellite Data Processing.

      SARViews — A fully automatic processing system that produces value-added products in support of monitoring natural disasters. The SARVIEWS processor is implemented in the Amazon Cloud and utilizes modern processing technology to generate geocoded and fully terrain corrected image time series, as well as interferometric SAR data over areas affected by natural disasters.

      Sentinel-1 Toolbox — A collection of processing tools, data-product readers and writers, and a display-and-analysis application to support the large archive of data from ESA SAR missions including SENTINEL-1, ERS-1 and -2, and ENVISAT, as well as third-party synthetic aperture radar (SAR) data from ALOS PALSAR, TerraSAR-X, COSMO-SkyMed and RADARSAT-2. 

      Worldview Quick Look Tool — This tool from NASA’s EOSDIS provides the capability to interactively browse global, full-resolution satellite imagery and then download the underlying data. Most of the 100+ available products are updated within three hours of observation.

      Commercial Tools

      ENVI — ENVI provides advanced, user-friendly tools to read, explore, prepare, analyze and share information extracted from all types of imagery.

      ERDAS IMAGINE — ERDAS IMAGINE performs advanced remote sensing analysis and spatial modeling to create new information.

      GAMMA — The GAMMA SAR and Interferometry Software is a collection of programs that allows processing of SAR, interferometric SAR (InSAR) and differential interferometric SAR (DInSAR) data for airborne and spaceborne SAR systems.

      Geomatica — Geomatica is a single, integrated software system for remote sensing and image processing.