ALOS-2 PALSAR

Long name PALSAR2
Short name PS2
Sensor type Synthetic-aperture radar (SAR)
Platform Advanced Land Observing Satellite-2 (ALOS-2)
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-*, summary.txt
Supported file extensions LED-*, IMG-*, *.txt, *.tif
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-2 PALSAR has several acquisition modes, each designated by a three-letter code. The last letter of each code designates the polarization:
  • S (Single)
  • D (Dual)
  • Q (Quad)
Each mode is described in the following tables.
Note: The information provided herein is based on the reference documentation cited under References.
Mode Swath width (km) Resolution (range x azimuth, m)* Polarization Description/notes
Spotlight [SBS] 25 ≈3.0 x 1.0 [SBS] Single (HH or HV or VH or VV) Acquisition mode with the finest spatial resolution and a narrow swath.
Stripmap UltraFine [UB] 55 ≈3.0 x 3.0

[UBS] Single (HH or HV or VH or VV)
[UBD] Dual (HH+HV or VH+VV)

N/A
Stripmap High-sensitive [HB] 55 ≈6.0 x 4.3

[HBS] Single (HH or HV or VH or VV)
[HBD] Dual (HH+HV or VH+VV)

N/A
Stripmap Fine [FB] 70 ≈9.1 x 5.3

[FBS] Single (HH or HV or VH or VV)
[FBD] Dual (HH+HV or VH+VV)

N/A
Fully Polarimetric High-sensitve [HQB] 55 ≈5.1 x 4.3 [HQB] Quad (HH+HV+VH+VV) N/A
Fully Polarimetric Fine-sensitve [FQB] 70 ≈8.7 x 5.3 [FQB] Quad (HH+HV+VH+VV) N/A
ScanSAR Nominal 28 MHz [WW] 350 ≈47.5 x 77.7

[WWS] Single (HH or HV or VH or VV)
[WWD] Dual (HH+HV or VH+VV)

N/A
ScanSAR Nominal 14 MHz [WB] 350 ≈95.1 x 77.7

[WBS] Single (HH or HV or VH or VV)
[WBD] Dual (HH+HV or VH+VV)

N/A
ScanSAR Wide [VB] 490 ≈44.2 x 56.7

[VBS] Single (HH or HV or VH or VV)
[VBD] Dual (HH+HV or VH+VV)

N/A

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

ALOS-2 PALSAR has five processing levels, as described in the following table.

Processing level Acquisition mode Description/notes

1.0
(RAW)

Not supported Data corresponding to a scene area is extracted from received data. The data type is 8-bit.

In multipolarization modes, the number of SAR data files is equal to the number of polarizations.

In ScanSAR mode, the data file is not divided for each scan.

1.1
Single-look complex (SLC)

[SBS]
[UBS], [UBD]
[HBS], [HBD]
[FBS], [FBD]
[HBQ]
[FBQ]

The range and single-look azimuth compressed data is represented by complex I and Q channels to preserve the magnitude and phase information. The range coordinate is in slant range. Level 1.1 imagery is focused to zero Doppler direction.

In ScanSAR mode, an image file is generated for each scan.

Note: CATALYST Professional does not support processing of ScanSAR ([WW], [WB], [VB]) Level 1.1 data.

1.5
Detected

[SBS]
[UBS], [UBD]
[HBS], [HBD]
[FBS], [FBD]
[HBQ]
[FBQ]
[WWS], [WWD]
[WBS], [WBD]
[VBS], [VBD]

The range and multilook azimuth compressed data is represented by amplitude data. The range coordinate is also converted from slant range to ground range, and map projection is performed.

Image coordinates are either in geocoded (G) or georeferenced (R) format. A georeferenced image is an image oriented in parallel with orbit direction. A geocoded image is an image projected on a map which is oriented in a map north-south direction.

2.1
Detected

[SBS]
[UBS], [UBD]
[HBS], [HBD]
[FBS], [FBD]
[HBQ]
[FBQ]
[WWS], [WWD]
[WBS], [WBD]
[VBS], [VBD]

Level 2.1 data is orthorectified from Level 1.1data by using a digital elevation model (DEM). Image coordinates are geocoded according to a map projection.
Possible projections are:
  • UTM
  • UPS
  • Mercator (MER)
  • Lambert Conical Conform (LCC)

3.1
Detected

[SBS]
[UBS], [UBD]
[HBS], [HBD]
[FBS], [FBD]
[HBQ]
[FBQ]
[WWS], [WWD]
[WBS], [WBD]
[VBS], [VBD]

Corrections in image quality, such as noise reduction and dynamic-range compression, are performed at that of Level 1.5 data.

Distribution disk files

ALOS-2 PALSAR data is distributed in CEOS and GeoTIFF formats.

Table 1. CEOS
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.
BRS-*.jpg JPEG No Thumbnail image.
*.kml Keyhole Markup Language No Image footprint. Not available for Level 1.1 products.

Table 2. GeoTIFF
File name Format Required Contents/details
summary.txt ASCII Yes Key file name. The summary file includes the information for creating processed data created at ALOS-2 data Processing System. The file is always made in a pair with its processed data.
IMG-*tif GeoTIFF Yes Image data. An integer value is indicated to each pixel. Geographic information and map projection are written in the header. One image file per polarization.
LUT-*.txt ASCII Yes The text file that summarizes the factor for converting each pixel value (integer) of a GeoTIFF file to a sigma-nought value (real). One file per polarization.

Returned data for supported format

ALOS-2 PALSAR data can be opened directly in its raw vendor format or imported into a PCIDSK (*.pix) file by using the key file name (LED-* for CEOS, summary.txt for GeoTIFF). 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. Only the fully supported processing levels and acquisition modes are listed.

Data product Data returned Details

Level 1.1 (SLC)
[SBS]
[UBS]
[HBS]
[FBS]

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

1 x [ORB] orbit segment
1 x [ARR] incidence angle array

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

Level 1.1 (SLC)
[SBD]
[UBD]
[HBD]
[FBD]

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

1 x [ORB] orbit segment
1 x [ARR] incidence angle array

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

Level 1.1 (SLC)
[HBQ]
[FBQ]

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

1 x [ORB] orbit segment
1 x [ARR] incidence angle array

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

Level 1.5, Level 2.1, Level 3.1
[SBS]
[UBS]
[HBS]
[FBS]
[WWS]
[WBS]
[VBS]

1 x [16U] raster channel (uncalibrated)
—or—
1 x [32R] raster channel (calibrated)

1 x [ORB] orbit segment

Detected data in amplitude.

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

Level 1.5, Level 2.1, Level 3.1
[SBD]
[UBD]
[HBD]
[FBD]
[WWD]
[WBD]
[VBD]

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

1 x [ORB] orbit segment

Detected data in amplitude.

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

To conduct a polarimetric analysis, Level 1.1 data is required.

References

ALOS-2/PALSAR-2 Level 1.1/1.5/2.1/3.1 CEOS SAR Product Format Description. Japan Aerospace Exploration Agency (JAXA). May 23 2014. 82 pages.

ALOS-2/PALSAR-2 Level 1.1/1.5/2.1/3.1 GeoTIFF Product Format Description. Japan Aerospace Exploration Agency (JAXA). May 23, 2014. 56 pages.

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

© PCI Geomatics Enterprises, Inc.®, 2023. All rights reserved.