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ASAR Data Formats Products
Geolocation Grid ADSRs
Doppler Centroid parameters
Chirp parameters
Antenna Elevation pattern
ASAR external characterization data
ASAR external calibration data
Level 0 SPH
Level 0 MDSR
SPH for auxiliary data with N=1 DSDs
Wave Mode Geolocation ADS
ASAR Wave Mode Products Base SPH
Slant Range to Ground Range conversion parameters
Measurement Data Set containing spectra. 1 MDSR per spectra.
Ocean Wave Spectra
Map Projection parameters
ASAR Image Products SPH
Measurement Data Set 1
Auxilliary Products
ASA_XCH_AX: ASAR External characterization data
ASA_XCA_AX: ASAR External calibration data
ASA_INS_AX: ASAR Instrument characterization
ASA_CON_AX: ASAR Processor Configuration
Browse Products
ASA_WS__BP: ASAR Wide Swath Browse Image
ASA_IM__BP: ASAR Image Mode Browse Image
ASA_GM__BP: ASAR Global Monitoring Mode Browse Image
ASA_AP__BP: ASAR Alternating Polarization Browse Image
Level 0 Products
ASA_WV__0P: ASAR Wave Mode Level 0
ASA_WS__0P: ASAR Wide Swath Mode Level 0
ASA_MS__0P: ASAR Level 0 Module Stepping Mode
ASA_IM__0P: ASAR Image Mode Level 0
ASA_GM__0P: ASAR Global Monitoring Mode Level 0
ASA_EC__0P: ASAR Level 0 External Characterization
ASA_APV_0P: ASAR Alternating Polarization Level 0 (Cross polar V)
ASA_APH_0P: ASAR Alternating Polarization Level 0 (Cross polar H)
ASA_APC_0P: ASAR Alternating Polarization Level 0 (Copolar)
Level 1 Products
ASA_IMS_1P: ASAR Image Mode Single Look Complex
ASA_IMP_1P: ASAR Image Mode Precision Image
ASA_IMM_1P: ASAR Image Mode Medium Resolution Image
ASA_IMG_1P: ASAR Image Mode Ellipsoid Geocoded Image
ASA_GM1_1P: ASAR Global Monitoring Mode Image
ASA_APS_1P: ASAR Alternating Polarization Mode Single Look Complex
ASA_APP_1P: ASAR Alternating Polarization Mode Precision Image
ASA_APM_1P: ASAR Alternating Polarization Medium Resolution Image product
ASA_WSS_1P: Wide Swath Mode SLC Image
ASA_WVS_1P: ASAR Wave Mode Imagette Cross Spectra
ASA_WSM_1P: ASAR Wide Swath Medium Resolution Image
ASA_APG_1P: ASAR Alternating Polarization Ellipsoid Geocoded Image
Level 2 Products
ASA_WVW_2P: ASAR Wave Mode Wave Spectra
ASAR Glossary Terms
Sea Ice Glossary
Land Glossary
Oceans Glossary
Geometry Glossary
ASAR Instrument Glossary
Acronyms and Abbreviations
ASAR Frequently Asked Questions
The ASAR Instrument
Instrument Characteristics and Performance
Inflight Performance Verification
Preflight Characteristics and Expected Performance
Instrument Description
Internal Data Flow
ASAR Instrument Functionality
Payload Description and Position on the Platform
ASAR Products and Algorithms
Auxiliary Products
Common Auxiliary Data Sets
Auxiliary Data Sets for Level 1B Processing
Summary of Auxiliary Data Sets
Instrument-specific Topics
Level 2 Product and Algorithms
Level 2 Product
ASAR Level 2 Algorithms
Level 1B Products
ASAR Level 0 Products
Level 0 Instrument Source Packet Description
Product Evolution History
Definitions and Conventions
Organisation of Products
ASAR Data Handling Cookbook
Hints and Algorithms for Higher Level Processing
Hints and Algorithms for Data Use
ASAR Characterisation and Calibration
The Derivation of Backscattering Coefficients and RCSs in ASAR Products
External Characterisation
Internal Calibration
Pre-flight Characterisation Measurements
ASAR Latency Throughput and Data Volume
Data Volume
Products and Algorithms Introduction
Child Products
The ASAR User Guide
Image Gallery
Further Reading
How to Use ASAR Data
Software Tools
How to Choose ASAR Data
Special Features of ASAR
Geophysical Coverage
Principles of Measurement
Scientific Background
Geophysical Measurements
ASAR Product Handbook
ASAR instrument characterization data
Wave Mode processing parameters
ASAR processor configuration data
Main Processing parameters
ASA_WVI_1P: ASAR Wave Mode SLC Imagette and Imagette Cross Spectra
Product Terms
RADAR and SAR Glossary
Level 1B Products
Summary of Applications vs Products
Site Map
Frequently asked questions
Terms of use
Contact us


1.2.1 Software Tools

ASAR products are delivered in the standard ENVISAT data format. Having received the data, the following categories of software tools can be used to explore ASAR products (see index) General Software Tools

Users may wish to directly decode data in the ENVISAT format themselves, to allow subsequent visualisation and further processing in languages such as C, or in commonly available software packages such as IDL, ENVI and Erdas Imagine.

The EnviView tool, which is discussed in detail in the ENVISAT Handbook, can also be used to convert ENVISAT data into hdf files. As briefly discussed in the next section, "EnviView," this ENVISAT tool is not intended for the detailed analysis, visualisation, and processing of ENVISAT data. Other commercial and proprietary tools provide these facilities in great detail and with many specialised options. The difference between such tools and EnviView is that they are usually aimed at certain classes of data, such as images or atmospheric data, or even data for a particular instrument. EnviView, however, is a single solution for all ENVISAT products. EnviView is intended as a stepping stone between these tools and the proprietary data format used for ENVISAT data. The data can then be automatically read by any software supporting this format.

Some other tools that may be used for more detailed analysis are provided below. Some are not ASAR specific.

  • IDL (Interactive Data Language) a general purpose graphical and scientific computing system
  • CAESAR image processing (speckle reduction) from NAS Software at
  • DORIS Insar software (open-source) at
  • Earthview InSAR from PGI Geomatics at
  • ENVI from Research Systems at based on the IDL product
  • ERS SAR toolbox described at and available at
  • GAMMA sells modular SAR processor software, and interferometric SAR and differential SAR processors
  • GEOimage software for processing Earth-observation imagery
  • Geomatica (remote-sensing image processing, cartography, photogrammetry)
  • IMAGINE Professional (remote sensing scene analysis, radar analysis, mapping)
  • Matlab includes a number of optional toolboxes including Signal Processing, System Identification, Fuzzy Logic, Image Processing, Mapping, Neural Networks.
  • Mathematica
  • Noesys (data exploration and visualisation) from Research Systems
  • PulSAR from Phoenix Systems,
  • PV-WAVE data manipulation, visualisation, statistics. Image Processing and Signal Processing toolkits available.
  • SARscape EnviView

The EnviView tool, developed by ESA, is described in detail in the ENVISAT Handbook. In general, however, EnviView is a tool capable of opening and decoding data in a format exclusive to the ENVISAT Ground Segment, known as Payload Data Segment (PDS) format. It then displays the data as simple text in HTML format, as graphs, or as images when these are appropriate.

As with the data from all of the ENVISAT instruments, the EnviView is a simple tool to provide a first look at ASAR data files in the PDS format. It uses a graphical user interface for data exploration and visualisations and is intended for the following purposes:

  • To be able to open any Level 0, 1b, Level 2 or auxiliary PDS data file.
  • To determine and display the contents of a file and the value of any given fields in any data set, except raw source packets (level 0 data).
  • To provide basic visualisation of data through simple 2D graphs and images.
  • To visualise certain high level data sets in a meaningful manner where a 2D graph conveys little information,especially:
    • ASAR image data sets
    • ASAR Wave spectra.
  • To provide a representation of the geographic coverage on a rectangular map projection.
  • To export selected data to HDF, ASCII or binary data files, for analysis in COTS tools such as Mathematica, IDL, Excel, and so on..
  • To save the contents of a record as HTML text for inclusion in reports.
  • To provide support for printing and system clipboard (cut/paste)where possible.
  • To be highly portable and to reach as wide an audience as possible.
  • To be guaranteed to run on Unix,Windows and MacOS and potentially other platforms too.

Example of Level 1B Wave Product Cross Spectra
Figure 1.101 Example of Level 1B Wave Product Cross Spectra

Figure1.101 is an example of a level 1b wave product, as seen using the EnviView ASAR Wave Spectra View window. (See section entitled Wave Spectra ). A wave spectrum viewer displays a false colour polar plot showing level 1B or level 2 ASAR wave spectra data. Since the data values are complex, having both real and imaginary parts, various representations of the spectra are possible. Data from one record at a time is displayed with the option of displaying record data sequentially as a movie.

The ASAR level 1B wave spectrum data is complex, containing both real and imaginary parts. EnviView only displays scalar (1 dimensional) values on the ASAR wave spectrum viewer, which means that it can only display either the real parts, the imaginary parts, or some scalar combination of the real and imaginary parts.

ASAR Level 2 data is not complex, hence there is no need to have selection provided for different display types when viewing such a data set. Level 2 data is neither symmetric nor anti-symmetric, and contains information for the entire 360 spectrum.

The complete instructions for the use and application of the EnviView viewer are provided in the EnviView User Guide that is included with the viewer when it is delivered to the customer. ASAR Toolbox

The Basic Envisat SAR Toolbox (BEST) is a collection of executable software tools that has been designed to facilitate the use of ESA SAR data. The purpose of the Toolbox is not to duplicate existing commercial packages, but to complement them with functions dedicated to the handling of SAR products obtained from ASAR (Advanced Synthetic Aperture Radar) and AMI (Active Microwave Instrument) onboard Envisat and ERS 1&2 respectively.

The Toolbox operates according to user-generated parameter files. The software is designed with an optional graphical interface that simplifies specification of the required processing parameters for each tool and (for Windows versions only) sets it running.

The interface doesn't include a display function. However, it includes a facility to convert images to TIFF or GeoTIFF format so that they can be read by many commonly available visualisation tools. Data may also be exported in the BIL format for ingestion into other image processing software, and the tools may be integrated within (for example) IDL.

The tools are designed to achieve the following functions:

  • Data Import and Quick Look: generation of quick-look and full resolution internal format files from a variety of ESA SAR products and import of TIFF and GeoTIFF images and generic raster data.
  • Data Export: output of data to selected common formats (TIFF, Geo TIFF and BIL).
  • Data Conversion: conversion between different image formats (e.g. power to amplitude) and transformation of the data by flipping or slant range to ground range reprojection.
  • Statistical: calculation of global or local statistical parameters from real image data and computation of the principal components of multiple images. Resampling: over- and under- sampling of an image by means of spatial and spectral methods.
  • Co-registration and Coherence Generation: automatic co-registration of both real and complex images, calculation of interferometric coherence and application of automatic geo-correction.
  • Radiometric Resolution Enhancement: improvement of the radiometric resolution of a backscatter image.
  • Calibration: radiometric correction of an input image to a variety of levels.

The Toolbox has been designed to handle ESA data products from both the Envisat ASAR instrument and the AMIs on ERS 1&2.

ASAR data acquired in Image Mode, Wide Swath Mode, Alternating Polarisation Mode and Global Monitoring Mode, processed to Level 0 or Level 1b (SLC, Precision, Medium Resolution or Ellipsoid Geo-coded), is supported.

Image Data from ERS SAR, processed as RAW, SLC, SLCI, PRI, GEC or GTC, is also supported.

The Toolbox handles the standard Envisat product file format. For ERS data, products generated within the ESA ERS ground segment at D-PAF, I-PAF, UK-PAF and ESRIN are supported, plus data from non-ESA PAF stations, if they are delivered with ESA CEOS annotations.

More information is available from the envisat web site at