About BEST

Last update: February 2009

This page provides more in-depth information about BEST and details of how to download and run the software.

Algorithms

BEST consists of a set of processing tools divided into the following groups:

• Data Import and Quick Look: For extracting data from Envisat ASAR and ERS SAR products held on any media (CD-ROM/DVD/EXABYTE/hard disk) in a standard ESA format. Also for importing TIFF and GeoTIFF images, generic raster data and ancillary data. Quick Look tool for generating reduced-size TIFF images of datasets directly from original products or from files created by BEST in internal format.

• Data Export: For converting data from the Toolbox's internal format to the common image formats TIFF, GeoTIFF or BIL, to allow visualisation of processing results. Data may be exported as a single channel, as a RGB false-colour composite or in multi-channel binary files. See Known issues and bugs for details of how to view output TIFF image files.

• Data Conversion: For converting between different image formats (e.g. between byte and float, power and amplitude) and performing basic mathematical operations on images. Also for altering image orientation (flipping) and transforming data from slant range to ground range. Additional tool for calculating the sensitivity vectors for points in an image. ASAR WSS functionalities: Detection and azimuth mosaicking, Range mosaicking and multilook.

• Statistical Tools: For calculating global or local statistical parameters from real image data and computing the principal components of multi-dimensional datasets.

• Resampling Tools: For resampling an image (real or complex) by both spatial and spectral methods.

• Co-registration and Support for Interferometry: For automatic co-registration of both real and complex images, to varying levels of precision, and evaluation of associated residuals, quality and coherence values. Also for generating an optimised coherence image and computing the interferometric altitude of ambiguity. Additional tools for deriving orbital baselines from pairs of DORIS files.

• Radiometric Resolution Enhancement: A Gamma MAP speckle filtering tool for increasing the radiometric resolution of the backscatter image. The filter can be used with real or complex images and has a range of parameters configurable by the user.

• Image Geo-correction: geocoding process to georeference input ASAR ground range detected product (i.e. ASA_IMP_1, ASA_IMM_1, ASA_WSM_1 etc.) and ERS-PGS (IMP, IMM) data. It uses the Geolocation Annotation in the product header to reproject the data to a flat earth ellipsoid (no kind of terrain relief is considered for such operation).

• Calibration Tools: Algorithms for performing various levels of radiometric correction to an input image, including the generation of an image in which the pixel values represent the backscattering coefficient. The calibration tool is based for ERS on the document Derivation of backscattering coefficient in ERS SAR PRI images (version 2.c), for ENVISAT on the document Absolute Calibration of ASAR level 1 products generated with PF-ASAR. Also for replacing the antenna pattern used to calibrate an ASAR product (retro-calibration) and enhancing ASAR Wide-swath images by correcting incidence angle effects in range and smoothing the steps between ScanSAR sub-swaths.

Input Data

• Envisat ASAR acquired in Image Mode, Wide-swath Mode, Alternating Polarisation Mode and Global Monitoring Mode and processed to Level 1b (SLC, Precision, Medium Resolution or Ellipsoid Geo-coded);

• ERS SAR data processed to level 1 by VMP ERS processor in CEOS format as SLC, PRI, GEC or GTC* products;

• ERS SAR data processed to level 1 by PGS ERS processor in CEOS and Envisat format (.e1, .e2) as SLC (IMS), PRI (IMP), IMG*

• ASAR and ERS RAW data (level 0): the Header Analysis only is allowed.

* see Known issues and bugs page

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 many of the foreign stations.

Internal Data

The majority of BEST Toolbox functions operate on data that has been converted into the BEST internal format. Therefore it is always necessary to first read new data into the Toolbox format using the Data Import tools. All BEST Toolbox operations produce output data in the internal format and assign filename extensions that identify the tool used.

Running BEST

The algorithms of the Toolbox are executed by means of the Human Machine Interface (HMI). Users are able to specify parameters, select input files and name output files according to the algorithm in question.

For Windows™ users there are two HMI, one is a familiar Visual Basic interface and the other is written in Tcl (Tool Command Language) . For LinuX and SUN Solaris users it is available the Tcl HMI. The Tcl/Tk software, available for download from the Tcl Developer Xchange, must be installed prior to running BEST on these platforms.

Both HMIs essentially automate the generation and execution of ASCII ".ini" files that are required by the Toolbox. Some users may prefer to produce their own ".ini" files, or edit existing files, and run these directly from the command line (there are sample files on the Examples page of this website). It is perfectly possible to run the Toolbox without an HMI.

To run the Toolbox from the command line, type the command:

best C:/...../file_name.ini

where file_name.ini is an ASCII file containing the parameters necessary for a Tool's execution.

For processing data using a series of tools, it is possible to edit ".ini" files together into a macro ".ini" file so that the entire procedure may be executed by a single command.

OS Requirements

BEST is available for Windows, LinuX OS, SUN Solaris

It is recommended that BEST for Windows 98/2000/ME/NT/XP or LinuX is installed on a system with at least an Intel™ Pentium™ 3 processor running at 1.6 GHz and 512 MB RAM.

However, it would also be possible to run the software on a system with lower specifications.

Download

Before downloading the software, you must agree to ESA's License Terms and Conditions. You are also encouraged to provide some details about yourself. Whilst not compulsory, this will enable us to better understand and serve the needs of the BEST User Community.

The BEST package consists in an executable file for Windows versions and tar and gzip compressed for LinuX and SUN Solaris. The following link gives access to downloadable packages and instructions to install BEST on each of the supported platforms.

Download BEST

(Changes and improvements in version 4.2.2-b)

Once downloaded, decompress the files and run the installation package according to the instructions provided.

Warning: before installing a new version, it's recommended to uninstall the previous one .

Known issues and bugs

Any known software issues and bugs in BEST will be logged here.

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry