ALOS-1 PALSAR

Long name PALSAR1
Short name PS1
Sensor type Synthetic-aperture radar (SAR)
Platform Advanced Land Observing Satellite-1 (ALOS-1)
Frequency 1.2 GHz
Band (wavelength) L (22.9 centimeters)
Polarization HH, HV, VH, VV (fully polarimetric)
Key file name (use to open data set) LED-*, *.meta, *._ortho.dat
Supported file extensions LED-*, IMG-*, *.meta, *.SLC.par, *.SLC, *.lea, *.tif, *._ortho.dat, *._ortho.lea
Data distributor

Japan Aerospace Exploration Agency/Earth Observation Center (JAXA/EOC)
The ALOS Data Nodes
Japan Space Systems/Earth Remote Sensing Data Analysis Center (J-Spacesystems/ERSDAC)

Sections

Data product name and description
Distribution disk files
Returned data for supported format
References

Data product name and description

ALOS-1 PALSAR has four acquisition modes, as described in the following table.

Mode Swath width (km) Resolution (range x azimuth, m)* Polarization Description/notes
High-resolution [H] 70

10.0 x 10.0 (single)
20.0 x 20.0 (dual)

Single (HH or VV)
Dual (HH+HV or VV+VH)

Provides azimuth resolution for two looks.
Direct downlink [D] 70 20.0 x 10.0 Single (HH or VV) Provides azimuth resolution for two looks.
Polarimetric [P] 30 30.0 x 10.0 Quad (HH+HV+VH+VV) Provides azimuth resolution for two looks.
ScanSAR [W]

250 (three scans)
300 (four scans)
350 (five scans)

100.0 x 100.0 Single (HH or VV) Provides azimuth resolution for eight looks.

* Resolution is always single-look complex (SLC) unless noted otherwise.

ALOS-1 PALSAR products are distributed by two organizations:
  1. Japan Aerospace Exploration Agency (JAXA), which distributes PALSAR data in CEOS format in Level 1.0, Level 1.1, and Level 1.5.
  2. Japan Space Systems (ERSDAC), which distributes PALSAR data in several formats (CEOS, Vexcel, ERSDAC-ortho) in Level 1.0, Level 1.1, Level 1.5, Level 4.1, and Level 4.2.
Processing level Acquisition mode Description/notes

1.0
(RAW)

Not supported

Signal data, data type is 8-bit. The number of SAR data files is equal to the number of polarizations in dual-polarization and Polarimetric modes. In ScanSAR mode, data is not separated into individual scans.
8-bit(I) + 8-bit(Q).

1.1
Single-look complex (SLC)

JAXA-CEOS
ERSDAC-VEXCEL

[H]
[D]
[P]

Performs range and one-look azimuth compression. On the slant-range coordinate, the data is complex. Phase history is included.
32-bit(I) + 32-bit(Q), slant-range coordinate.

1.5
Detected

JAXA-CEOS

[H]
[D]
[P]
[W]

After performing range and multilook azimuth compression, performs radiometric and geometric corrections according to the map projection. Pixel spacing can be selected for Fine mode. Data is detected in amplitude format (16-bit unsigned integer).

Latitudes and longitudes in the product are calculated exclusive of the altitude. Products are available in georeferenced (GR) and geocoded (GC) format. A GR image is oriented in parallel with the direction of the orbit. A GC image is an image projected on a map that is oriented in a map north-south direction.

1.5
Detected

ERSDAC-CEOS
• SGF
• SSG

ERSDAC-GeoTIFF
• GeoTIFF geocoded
• GeoTIFF geocoded ortho

ERSDAC-Binary Geocoded Ortho

[H] single pol This product is generated from Level 1.1 data acquired in Fine mode with single-polarization and SAR processing applied. It consists of amplitude data sequences spaced equally on ground range.

Products are available in georeferenced (GR) and geocoded (GC) format. A GR image is oriented in parallel with the direction of the orbit. A GC image is an image projected on a map that is oriented in a map north-south direction.

SAR georeferenced fine beam (SGF) is derived from the similar RADARSAT-1 product.. SAR systematic geocoded (SSG) is derived from the similar RADARSAT-1 product. The signal data is observed under PALSAR high-resolution in single-polarization mode.

4.1
Detected

ERSDAC-CEOS
• SGP
• PSG

ERSDAC-GeoTIFF
• GeoTIFF geocoded
• GeoTIFF geocoded ortho

ERSDAC-Binary Geocoded Ortho

[H] (dual pol)
[P]

Level 4.1 products are generated from Level 1.0 data acquired in High-resolution mode (dual-polarization) or Polariametric mode.
SAR processing performed on Level 1.0 data includes the following:
  1. Range compression using Fast Fourier Transform (FFT)
  2. Secondary range compression using range-migration compensation
  3. Corrections to range-migration curvature
  4. Azimuth compression
  5. Multilook processing
  6. Conversion of coordinates system from slant range to ground range (geocoded data only)

Products are available in georeferenced (GR) and geocoded (GC) format. A GR image is oriented in parallel with the direction of the orbit. A GC image is an image projected on a map that is oriented in a map north-south direction.

Geocoded products are available in a variety of map projections and pixel spacing. Both are data on ground-range. Additionally, orthorectified Level 4.1 geocoded product is available.

An ortho product is made by applying SAR processing, orthorectification, and map projection. A digital elevation model (DEM), such as SRTM, is used for orthorectification. Two formats, GeoTIFF and ERSDAC format (Binary), are prepared for the products. There are two types of ortho products available:
  1. Orthorectified by using DEM (Standard ortho products)
  2. Orthorectified and local incident angle corrected by using DEM (Ortho products with local incident angle correction)

SAR georeferenced polarimetric (SGP): Signal data is observed in PALSAR dual-polarization or quad-polarization mode. Polarimetric systematic geocoded (PSG): Signal data is observed in PALSAR dual-polarization or quad-polarization mode.The SGP and PSG modes are derived from similar Radarsat-1 products.

4.2
Detected

ERSDAC-CEOS
• SCN
• SCG

ERSDAC-GeoTIFF
• GeoTIFF geocoded
• GeoTIFF geocoded ortho

ERSDAC-Binary Geocoded Ortho

[W] Level 4.2 products are generated from Level 1.0 data acquired in ScanSAR mode (single-polarization).
SAR processing performed on Level 1.0 data includes the following:
  1. Processing of ScanSAR Burst-mode data
  2. Range compression
  3. Corrections to range-migration curvature
  4. Azimuth compression by SPECAN chirp-Z transform
  5. Multilook processing
  6. Range multilook processing
  7. Overlay processing
  8. Conversion from slant range to ground range

Products are available in either georeferenced (GR) or geocoded (GC) format. A GR image is oriented in parallel with the direction of the orbit. A GC image is an image projected on a map that is oriented in a map north-south direction.

Geocoded products are available in a variety of map projections and pixel spacing. Both are data on ground range. Additionally, orthorectified Level 4.1 geocoded product is available.

An ortho product is made by applying SAR processing, orthorectification, and map projection. A digital elevation model (DEM), such as SRTM, is used for orthorectification. Two formats, GeoTIFF and ERSDAC format (Binary), are prepared for the products. There are two types of ortho products available:
  1. Orthorectified by using a DEM (standard ortho products)
  2. Orthorectified and local incident angle corrected by using a DEM (ortho products with local incident angle correction)

(ScanSAR systematic geocoded (SCG) and ScanSAR (SCN) are derived from similar RADARSAT-1 products. Signal data is observed in PALSAR Wide Area Observing mode.

Distribution disk files

JAXA-CEOS (Level 1.1 and Level 1.5)

File name Format Required Contents/details
LED-* Product-specific binary Yes Key file name. This file is located before the image file. It stores annotation, ancillary, and other types of data related to the image data in the succeeding image file.
IMG-* Product-specific binary Yes Image data, one image file per polarization. This file is located after the leader file. It stores the image data.
VOL-* Product-specific binary No Volume descriptor. This file is located at the beginning of the image volume and stores the volume-management and file-management information.
TRL-* Product-specific binary No This file is located after the image file. It stores the final information related to the image data.

ERSDAC Vexcel (Level 1.1)

File name Format Required Contents/details
*.meta Product-specific binary Yes Key file name. Metadata file in XML format.
*.SLC.par Product-specific binary Yes This file completely describes the characteristics of the floating-point SLC image data file.
*.SLC Product-specific binary Yes This file contains any of the following:
  • With a single polarization, two 4-byte channels
  • With two polarizations, four 4-byte channels
  • With four polarizations (floating point values [I and Q] per SLC pixel), eight 4-byte channels

ERSDAC-CEOS (Level 1.5, Level 4.1, and Level 4.2)

File name Format Required Contents/details
*_XXX.lea Product-specific binary Yes SAR leader file pointer record, where XXX is SGF, SSG, SGP, PSG, SCN, or SCG.
_XXX.dat Product-specific binary Yes Key file name. Image options file pointer record, where XXX is SGF, SSG, SGP, PSG, SCN, or SCG.
*_XXX.vol Product-specific binary No Volume descriptor record, where XXX is SGF, SSG, SGP, PSG, SCN, or SCG.
_XXX.tra Product-specific binary No SAR trailer file pointer record, where XXX is SGF, SSG, SGP, PSG, SCN, or SCG.
_XXX.nul Product-specific binary No Null volume descriptor record, where XXX is SGF, SSG, SGP, PSG, SCN, or SCG.
*.meta Product-specific binary No Metadata file in XML format.

ERSDAC binary ortho products (Level 1.5, Level 4.1, and Level 4.2)

File name Format Required Contents/details
*._ortho.dat Product-specific binary Yes Key file name. Image options file pointer record contents.
*._ortho.lea Product-specific binary Yes SAR leader file pointer record.
*_ortho.vol Product-specific binary No Volume descriptor record contents.
*._ortho.tra Product-specific binary No SAR trailer file pointer record contents.
*._ortho.nul Product-specific binary No N/A
*.meta Product-specific binary No Metadata file in XML format.

ERSDAC GeoTIFF ortho products (Level 1.5, Level 4.1, and Level 4.2)

File name Format Required Contents/details
*.meta Product-specific binary No Metadata file in XML format.
*.tif Tagged Image File Yes Image data.
*.tif.param ASCII N/A Metadata file in text format

Returned data for supported format

ALOS-1 PALSAR data can be opened directly in its raw vendor format or imported into a PCIDSK (*.pix) file by using the key file name. For optimal processing, use the PCIDSK format.

Warning: Data sets for this sensor are organized in a specific folder structure on disk. GDB uses this structure and the file names to identify the data product type. Do not alter the folder structure or any file names prior to data ingestion to ensure the image data and auxiliary information are imported correctly.

The following table describes the data structure after it is imported into a PCIDSK file.

Data product Data returned Details

JAXA-CEOS Level 1.1
[H] (single pol)
[D]

1 x [C16S] raster channel (uncalibrated)
—or—
1 x [C32R] raster channel (calibrated)

1x [GCP] ground control points
1 x [ORB] orbit segment
1 x [ARR] incidence angle array

  • Complex data
  • Data can be calibrated in sigma, gamma, or beta nought

JAXA-CEOS Level 1.1
[H] (dual pol)

2 x [C16S] raster channels (uncalibrated)
—or—
2 x [C32R] raster channels (calibrated)

1x [GCP] ground control points
1 x [ORB] orbit segment
1 x [ARR] incidence angle array

Data can be calibrated in sigma, gamma, or beta nought.

JAXA-CEOS Level 1.1
[P]

4 x [C16S] raster channels (uncalibrated)
—or—
4 x [C32R] raster channels (calibrated)

1x [GCP] ground control points
1 x [ORB] orbit segment
1 x [ARR] incidence angle array

Data can be calibrated in sigma, gamma, or beta nought.

JAXA-CEOS Level 1.5
[H] single pol
[D]
[W]

1 x [C16U] raster channel (uncalibrated)
—or—
1 x [32R] raster channel

1x [GCP] ground control points
1 x [ORB] orbit segment
1 x [ARR] incidence angle array

Data can be calibrated in sigma, gamma, or beta nought.

JAXA-CEOS Level 1.5
[H] dual pol

2 x [16U] raster channels (uncalibrated)
—or—
2 x [32R] raster channels (calibrated)

1x [GCP] ground control points
1 x [ORB] orbit segment
1 x [ARR] incidence angle array

Data can be calibrated in sigma, gamma, or beta nought.

JAXA-CEOS Level 1.5
[P]

4 x [16U] raster channels (uncalibrated)
—or—
4 x [32R] raster channels (calibrated)

1x [GCP] ground control points
1 x [ORB] orbit segment
1 x [ARR] incidence angle array

Data can be calibrated in sigma, gamma, or beta nought.
Note: For a fully polarimetric analysis, complex data (Level 1.1) is required.

ERSDAC-VEXCEL Level 1.1
[H] single pol
[D]

1 x [C32R] raster channel (calibrated)

1 x [ORB] orbit segment
1 x [TEX] main product annotation

Data is calibrated in beta nought.

ERSDAC-VEXCEL Level 1.1
[H] dual pol

2 x [C32R] raster channels (calibrated)

1 x [ORB] orbit segment
1 x [TEX] main product annotation

Data is calibrated in beta nought.

ERSDAC-VEXCEL Level 1.1
[P]

4 x [C32R] raster channels (calibrated)

1 x [ORB] orbit segment
1 x [TEX] main product annotation

Data is calibrated in beta nought.
Note: Support for ERSDAC products at Level 1.5, Level 4.1, and Level 4.2 has not been tested fully.

References

Earth Remote Sensing Data Analysis Center (ERSDAC). ERSDAC PALSAR GeoTIFF Product Format, Version R01. April 14, 2011. Document PG-E-E-0209-R01. 15 pages.

Earth Remote Sensing Data Analysis Center (ERSDAC). ERSDAC PALSAR Ortho Product Formats. Revised R03.0. July 13, 2011. Document PG-E-E-0155-R03.0. 81 pages.

Earth Remote Sensing Data Analysis Center (ERSDAC). ERSDAC PALSAR CEOS Format Specification. Document ERSDAC-VX-CEOS-004. Version date: May 12, 2009, version 1.8. 217 pages.

Japan Space Systems (J-spacesystems). PALSAR Reference Guide. 6th Edition. November 2012. 73 pages.

Japan Space Systems (J-spacesystems). PALSAR User’s Guide. 2nd Edition. November 2012. 69 pages.

Japan Aerospace Exploration Agency (JAXA), Earth Observation Research and Application Center. ALOS Data Users Handbook. Revision C. March 2008. 158 pages.

Japan Aerospace Exploration Agency (JAXA). ALOS/PALSAR Level 1.1/1.5 product format description (English version). Revision L, July 2009. Document NEB-070062B. 158 pages.

Vexel Corporation. Palsar Algorithm Description. August 8, 2003. Document VX-PALSAR-010. 72 pages.

For more information, go to: eorc.jaxa.jp

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