Introduction to BEST - European Space Agencyearth.esa.int/landtraining07/D3PB-1-Minchella.pdf · 5...

Introduction to BEST(Basic Envisat&ERS SAR Toolbox)

Andrea Minchella

5 September 2007, D3PB-1

5 September 2007 D3PB-1 Forest-Agriculture: Introduction to BEST software A. Minchella 2

BEST (Basic Envisat&ERS SAR toolbox) is a collection of executable

software tools that has been developed by ESA 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 the ASAR (Advanced

Synthetic Aperture Radar) onboard Envisat and the AMIs (Active

Microwave Instrument) onboard ERS 1&2.

http://earth.esa.int/best/

BEST overview


• Data Import and Quick Look

• Data Export

• Data Conversion

• Statistics

• Re-sampling

• Co-registration and Coherence Generation

• Radiometric Resolution Enhancement

• Calibration

Toolbox Functionalities


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


Data ExportConverting 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.


Data ConversionConvert between different image formats (e.g. Complex to amplitude, amplitude to power etc.) and perform 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.

StatisticsCalculate global or local statistical parameters from real image data and compute the principal components of multi-dimensional datasets.



Re-samplingOver- and under-sampling (both spatial and spectral)

Coregistration and Support for InterferometryAutomatic co-registration of both real and complex images 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 and geometrically correcting ASAR medium resolution products.




Radiometric Resolution EnhancementA 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.

CalibrationAlgorithms 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.


This practical session on BEST wants to illustrate

how is possible to get a time series of 3 co-

registered, calibrated and speckle-reduced ERS

2-SAR PRI data using BEST and ERDAS

BEST permits to handle ESA SAR data but it has not an efficient display for visualization, hence it is almost indispensable to use another SW package (in our case ERDAS).


Main Directory : C:\Lisbon_training_BEST\

How your training directory is organized

ERS2 DATA

In BEST_Working directory there will be all files generating using BEST

In ERDAS_Working directory there will be all files generating using ERDAS

!! Please check if you have all !!!

Please save YOUR FILES IN THESE DIRECTORIES and using the name reported in the following,

avoiding to leave in file name blank space


• ERS 2 PRI Product

• Frame 2682

• 7 August 1998 orbit 17239

• 25 December 1998 orbit 19243

• 9 April 1999 orbit 20746

Data


Location of the scene


Main Steps using BEST:

1. Header analysis: to extract the information data from the file.

2. Full Resolution Extraction: to extract the image from the ESA file

3. Quick Look Generation: to have a first look of the product.

4. Portion Extraction: to have a subset of the image.

5. Quick look and Ancillary Data Dump of the extracted portion

6. Calibration

a) Amplitude to Power

b) ADC compensation

c) Backscattering image

These steps will be done for each acquisition


7. Automatic Coregistation of backscattering images

8. Export to BIL format preserving the data and allowing the handling of the data with

other SW

Main steps using BEST

Main Steps using ERDAS

1. Import the BIL format into Erdas internal format (.img)2. Visualization3. Speckle suppression4. Layer stacking5. RGB visualization


Using BEST

C:\Lisbon_training_BEST\ BEST_Working

Before to start Setup Working directory


1. Header analysis

Using BEST - First image: 7 August 1998


2. Full Resolution Extraction



3. Quick Look Generation



4. Portion Extraction

Quick look

TL Row = 1500

TL Col = 500

BR Row = 4999

BR Col = 3999

3500 pixel

3500 pixel



5. Quick Look Generation of subset image



Quick Look of subset image

3500

3500



5. Ancillary Data Dump function permits to retrieve annotation about the image



6. Calibrationa) Amplitude to Powerb) ADC compensation




6. Calibrationa) Amplitude to Power

b) ADC compensationc) Backscattering image




b) ADC compensation




1. Header analysis

Using BEST - Second image: 25 December 1998



Quick look

TL Row = 1500

TL Col = 500

BR Row = 4999

BR Col = 3999

3500 pixel

3500 pixel





For time reason we skip step 5 not proper necessary



b) ADC compensation




1. Header analysis

Using BEST – Third image: 9 April 1999



Quick look

TL Row = 1500

TL Col = 500

BR Row = 4999

BR Col = 3999

3500 pixel

3500 pixel




For time reason we skip step 5 not properly necessary




b) ADC compensation




7. Automatic Co-registration of 3 Backscattering subset images (nearest neighbourhood re-sampling method)

Using BEST

1 2


Using BEST – Automatic co-registration

1. Custom parameters


2. Optional output parameters



Now we have generated 3 co-registered and calibrated images

A backscattering time series



8. Export to BIL format The BIL format preserves the radiometric values

Using BEST: BIL format


Using BEST: BIL format

From this point we use ERDAS


Main Steps 1. Import the BIL format into Erdas (.img)2. Visualization 3. Speckle suppression4. Layer stacking5. RGB visualization

Using ERDAS


Using ERDAS: import BIL format-7Aug1998


Using ERDAS: import BIL format-25 Dec 1998


Using ERDAS: import BIL format-9 Apr 1998


Using ERDAS: Visualization and Blend function


Using ERDAS: Speckle suppression- 7aug1998


Using ERDAS: Speckle suppression- 25 dec1998


Using ERDAS: Speckle suppression- 9 Apr 1999

9april1999.img 9april1999_speckle_reduced.img


Using ERDAS: Layer Stacking of speckle-reduced data

Layer orderLayer 1: 7 August 1998Layer 2: 25 December 1998Layer 3: 9 April 1999


Using ERDAS: Visualization RGB Layer Stacking

RGB visualizationLayer 1 (7 August 1998) REDLayer 2 (25 December 1998) GREENLayer 3 (9 April 1999) BLUE


Using ERDAS: Visualization RGB and FLIP

Flipping the image is visualized in a “like geographic system”


Using ERDAS: Visualization RGB and comments

Introduction to BEST - European Space Agencyearth.esa.int/landtraining07/D3PB-1-Minchella.pdf · 5...

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