Alaska Satellite Facility
Delivering Remote Sensing Data Since 1991

Contents

  1. CEOS
  2. GeoTIFF
  3. SAFE
  4. HDF5
  5. UAVSAR
  6. AIRSAR

1. CEOS (Committee on Earth Observation Satellites)

A standard format published in 1988, used for radar data and originally expected to be used with tape media. The format does not specify a naming convention.

Files, Content, and How to Open

Data format information for ASF's CEOS L1 and L1.5 (image) products:

File typeERS-1, ERS-2, JERS-1 and RSAT-1 file extension (L1)

ALOS PALSAR file prefix (L1.5)

SAR VOLUME fileN/AVOL-
SAR LEADER file.LLED-
SAR DATA file.DIMG-
SAR TRAILER file.PTRL-

CEOS data may be viewed using ASF's MapReady. ESA’s Sentinel-1 Toolbox (S1TBX) is also available.

The Volume descriptor file (VOL-) stores the volume-management and file-management information. 

The Leader file (.L, LED-) contains detailed metadata. Several useful records are the Dataset Summary, Platform Position, and the Facility-Related records. The leader file contents can be read in plain text if the .L.txt file is available.

The Data file (.D, IMG-) contains the image data. 

The Trailer file(.P) contains basic metadata including orbit, beam mode, start/stop times and lat/long corners and center. The trailer file can be read with a text editor.

The Trailer file (TRL) contains a file descriptor, and for L1.1 and L1.5 data, low resolution image data.

For users who do not wish to use MapReady or S1TBX, some useful information:

  • CEOS is a wrapper – image data are wrapped in an image file descriptor and record headers which must be discarded in order to work with the data. 
  • Each file starts with a file descriptor record, which provides details on the format used to store the data. In addition, there is one record header for each line of data. Each line has a 12-byte record header (which contains the record count in the file, record type identification, and record length in bytes); data values, and possibly fill values
  • Note that the units for state vectors may be either meters or kilometers (not a worry if using MapReady).


CEOS Data Recipes

For step-by-step workflows see the Data Recipes:
 How to View and Geocode CEOS Data in ASF MapReady
 How to Terrain Correct (RTC) CEOS-Format Data


Product Naming Conventions

The CEOS format does not specify a naming convention, so naming is facility or agency specific.

ERS-1, ERS-2, JERS-1, and RADARSAT-1 
Examples:
R1_65186_ST3_F287
R1_65186_ST3_L0_F287

L1 and L0 naming respectively:

  • Mission ID_Absolute Orbit_Beam Mode_Frame Number
  • Mission ID_Absolute Orbit_Beam Mode_Processing Level_Frame Number

ALOS PALSAR 
 

Granule Name
Example
:
ALPSRP273981290

  • Mission ID - AL
  • Sensor ID - PSR
  • Absolute Orbit - 27398
  • Frame Number - 1290

Product Name
Examples

IMG-HH-ALPSRP273981290-H1.0__A
IMG-HH-ALPSRP273981290-H1.5_UA

  • CEOS File Type - IMG 
  • Polarization - HH
  • Mission ID - AL
  • Sensor ID - PSR
  • Beam Mode - P
  • Absolute Orbit - 27398
  • Frame Number - 1290 
  • Observation Mode - H
  • Processing Level - 1.0
  • Map Projection -  U
  • Orbit Direction - A

Options

Beam Mode

  • S - Wide Beam (ScanSAR)
  • P - Fine single-pol, fine dual-pol, full-pol

Observation Mode

  • H - Fine mode
  • W - ScanSAR mode
  • D - Direct downlink mode
  • P - Polarimetry mode
  • C - Calibration mode

Map Projection

  • U - Universal Transverse Mercator (UTM)
  • P - Polar Stereo (PS)
  • M - Mercator
  • L - Lambert conformal conic (LCC)
  • _  "Not specified" (underscore)

CEOS Resources


2. GeoTIFF (Tagged Information File Format)

Format for handling images and data within a single raster file, by including header tags such as size, definition, image-data arrangement, and applied image compression.

The GIS-friendly GeoTIFF format is an extension of TIFF that includes georeferencing or geocoding information embedded within a TIFF file (such as latitude, longitude, map projection, coordinate systems, ellipsoids, and datums) so an image can be positioned correctly on maps of Earth. It is a public domain metadata standard. 

A georeferenced image is oriented in parallel with orbit direction:

Descending: The scene start is at the top of the image, and scene end is at the bottom.


Ascending: The scene end is at the top of the image, and the scene beginning is at the bottom

geocoded image is projected on a map oriented in a north-south direction:

DescendingAscending
Credit: JAXA ALOS/PALSAR Level 1.1/1.5 Product Format Description document


ASF DAAC SAR datasets available in GeoTIFF format

  • Sentinel – Georeferenced
  • ALOS PALSAR RTC – Geocoded
  • Seasat – Geocoded


GeoTIFF Data Recipes

How to View Radiometrically Terrain Corrected (RTC) Images in GIS Environments For ALOS PALSAR RTC products
Three recipes for radiometric terrain correction of Sentinel-1 synthetic aperture radar (SAR) data  For Sentinel GRD products


Sentinel Naming Convention


ALOS PALSAR RTC Naming Convention

ALOS PALSAR Radiometrically Terrain Corrected (RTC) products are gamma naught, suitable for statistical analysis. For better viewing in GIS, convert to db or amplitude with these directions.

Product Name

Example:
AP_26939_FBS_F3170_RT1
Mission IDAP
Absolute Orbit 26939
Beam ModeFBS
Frame Number F3170
Terrain Correction Resolution (1=high, 2=low)RT1

Product Filename Extensions

File ExtensionDescriptionExample

_HH.tif _HV.tif _VH.tif _VV.tif

Terrain-corrected product stored in separate files for each available polarization in GeoTIFF format

AP_26939_PLR_F3170_RT1_HH.tif
AP_26939_PLR_F3170_RT1_HV.tif
AP_26939_PLR_F3170_RT1_VH.tif
AP_26939_PLR_F3170_RT1_VV.tif

.iso.xmlISO compliant metadata in XML formatAP_26939_PLR_F3170_RT1.iso.xml
.inc_map.tifIncidence angle Map in GeoTIFF format

AP_26939_PLR_F3170_RT1.inc_map.tif

.ls_map.tifLayover/shadow mask in GeoTIFF formatAP_26939_PLR_F3170_RT1.ls_map.tif
.dem.tifDigital elevation model used for terrain correction in GeoTIFF formatAP_26939_PLR_F3170_RT1.dem.tif
.geo.jpgBrowse image of the amplitude (including world and auxiliary file) in JPEG format

AP_26939_PLR_F3170_RT1.geo.jpg

.kmzBrowse image in Google Earth formatAP_26939_PLR_F3170_RT1.kmz


Seasat Naming Convention

Granule Name

Example
:
SS_01492_STD_F2829.tif

  • Mission ID - SS 
  • Absolute Orbit - 01492 
  • Beam Mode - STD 
  • ESA Frame Number - F2829 



3. SAFE (Standard Archive Format for Europe)

Sentinel data products use a Sentinel-specific variation of the SAFE format, an ESA folder structure containing data and information as follows:

  • Manifest.safe - general product information in XML Annotation - product metadata in XML as well as calibration data
  • Annotation - product metadata in XML as well as calibration data
  • Measurement - image data in various binary formats (georeferenced GeoTIFFs for Sentinel L1 and SLC data) 
  • Preview - quick-looks in PNG format, Google Earth overlays in KML format, and HTML preview files
  • Support - XML schemes describing the product XML


SAFE Product Folder Structure


The manifest.safe file is an XML file containing the mandatory product metadata common to all Sentinel-1 products.

Annotation datasets contain metadata describing the properties and characteristics of the measurement data or how they were generated. For each band of data there is a product annotation data set that contains metadata describing the main characteristics corresponding to that band such as the state of the platform during acquisition, image properties, polarization, Doppler information, swath merging and geographic location. Calibration annotations contain calibration information and the beta naught, sigma naught, gamma and digital number look-up tables that can be used for absolute product calibration. Noise data annotations contain the estimated thermal noise look-up tables. Annotated data sets are provided in XML format.

Measurement datasets contain the binary information of the actual acquired or processed data. For Level-0 this is the instrument data, for Level-1 it is processed data. There is one measurement data set per polarization and per swath. TOPSAR SLC products contain one complex measurement data set in GeoTIFF format (georeferenced) per swath per polarization. Level-1 GRD products contain one detected measurement data set in GeoTIFF format (georeferenced) per polarization.

In the Preview folder, quick-look datasets are power detected, averaged and decimated to produce a lower resolution version of the image. Single polarization products are represented with a grey scale image. Dual polarization products are represented by a single composite color image in RGB with the red channel (R) representing the first polarization, the green channel (G) represents the second polarization and the blue channel (B) represents an average of the absolute values of the two polarizations.

Representation datasets found in the Support folder contain information about the format or syntax of the measurement and annotated data sets and can be used to validate and exploit these data. Representation data sets are provided as XML schemas.

Measurement datasets are provided in GeoTIFF format (georeferenced) for Level-1 products.


Sentinel-1 Naming Convention

The top-level Sentinel-1 product folder name is composed of upper-case alphanumeric characters separated by an underscore (_).

Sentinel-1 Naming Convention

Example:
S1A_IW_SLC__1SDV_20170413T131907_20170413T131934_016126_01AA29_8754.SAFE 

  • Mission Identifier (MMM) - S1A. Options: S1A or S1B
  • Mode/Beam (BB) - IW. Options: S1-S6 beams or IW, EW or WV
  • Product Type (TTT) - SLC. Options: RAW, SLC, GRD or OCN
  • Resolution (R) (SLC or OCN only) - _. Options: F (Full resolution), H (High resolution), M (Medium resolution) or _ (underscore: not applicable)
  • Processing Level (L) - 1. Options: 0, 1 or 2
  • Product Class - S. Options: Standard (S) or Annotation (A). Annotation – internal only, not distributed
  • Polarization (PP) - DV. Options:
    • SH (single HH polarization)
    • SV (single VV polarization)
    • DH (dual HH+HV polarization)
    • DV (dual VV+VH polarization)
  • Start/Stop Date-Time - 20170413T131907. YYYYMMDDThhmmss. Date and time, separated by the character 'T'
  • Absolute orbit (OOOOO) - 016126.  Options: 000001-999999
  • Mission data-take ID (DDDDDD) - 01AA29. Options: 000001-FFFFFF
  • Product unique identifier (CCCC) - 8754. 
  • The folder extension is always "SAFE"


4. HDF5

Hierarchical Data Format (HDF) is a set of file formats designed to store and organize large amounts of data.

HDF5 simplifies the file structure to include only two major types of object:

  • Datasets, which are multidimensional arrays of a homogeneous type
  • Groups, which are container structures which can hold datasets and other groups

HDF5 is a general purpose file format and programming library for storing scientific data. Use of the HDF library enables users to read HDF files on multiple platforms regardless of the architecture the platforms use to represent integer and floating point numbers.

ASF DAAC SAR datasets available in HDF5 format and tools

    • Seasat products are offered in either HDF5 or GeoTIFF formats. HDF5 products may be viewed with MapReady.
    • All SMAP standard products are in the Hierarchical Data Format version 5 (HDF5). SMAP products can be viewed with Panoply.

    Seasat HDF5 Data Recipe

    How to View Seasat HDF5 Files in ASF MapReady 

    Seasat Naming Convention

    Example:
    SS_01492_STD_F2829.h5

    • Mission ID - SS
    • Absolute Orbit - 01492
    • Beam Mode - STD (standard)
    • F - Indicates frame number follows
    • ESA Frame Number - 2829
    • Data Format - .h5

    SMAP Level 1A Radar Product Naming Convention

    Example:
    SMAP_L1A_RADAR_00934_A_20141225T074951_ R04000_002. h5

    • Mission ID - SMAP
    • Processing Level - L1A_RADAR
    • Orbit Number = 00934
    • Flight Direction - A. Ascending or Descending
    • First Date/Time Stamp: 20141225T074951  YYYYMMDD T hhmmss
    • Composite Release ID - R04000.
      • 'R' is always used. 
      • Launch Indicator - 0.  “0”: calibration data  “1”: post-calibration data
      • Major ID - 4.  incremented by major changes in algorithm or processing approach
      • Minor ID - 000. Incremented by changes to data processing, such as algorithm, software, or parameters
    • Product Counter - 002 
    • Extension – Data format: .h5 = HDF5, .qa = QA products


    5. UAVSAR 

    Polarimetric Product Format

    The format of the following files are described:

    SLC files (.slc): calibrated single look complex files for each polarization (HH, HV, VH, and VV), floating point format, little endian, 8 bytes per pixel, corresponding to the scattering matrix.

    MLC files (.mlc): calibrated multi-looked cross products, floating point format, three files 8 bytes per pixel, three files 4 bytes per pixel, little endian.

    Compressed Stokes Matrix product (.dat): AIRSAR compressed stokes matrix format for software compatibility (http://airsar.jpl.nasa.gov/data/data_format.pdf). 10 bytes per pixel.

    Ground projected files (.grd): calibrated complex cross products projected to the ground in simple geographic coordinates (latitude, longitude). There is a fixed number of looks for each pixel. Floating point, little endian, 8 or 4 bytes per pixel.

    Hgt file: the DEM that the imagery was projected to, in the same geographic coordinates as the ground projected files. Floating point (4 bytes per pixel), little endian, ground elevation in meters.

    Annotation file (.ann): a text file with metadata.

    Terrain slope file (.slope): The terrain slope file (.slope) contains the derivatives of the digital elevation model (DEM) in the east and north directions. The file is an array of two interleaved floating point numbers (2 x 4 bytes per pixel) with geometry identical to the other ground-projected data layers (.grd, .hgt, .inc). For each interleaved pixel, the first 4 byte value is the terrain slope in the east direction, and the second 4 byte value is the slope in the north direction. Floating point, little endian. 

    Incidence angle file (.inc): the local incidence angle, the angle between the surface normal and the radar line of site. The file consists of 4-byte floating point values, coregistered with the slope file. The floating point, little endian file contains values reported in radians:

    UAVSAR Polarimetric File Naming Convention

    Product Name

    Example:
    Dthvly_34501_08038_006_080731_L090HH_XX_01.slc

    • Site Name - Dthvly
    • Heading of flight - 345
    • Counter number - 01
    • Year -08
    • Number of flights in Year  - 38
    • Number of data takes in flight (7th) - 006
    • YYMMDD of acquisition UTC - 080731
    • L -Band – L
    • Steering Angle - 090 (angle pointing from flight heading)
    • Polarization, transmit/receive - HH
    • XX – XX, no cross talk calibration. CX, cross talk calibration has been applied
    • Processing version number - 01
    • Data type is single look complex - .slc

    Data format description

    SLC data:

    The SLC is a pure binary file (complex floating-point, 8 bytes per pixel) with no header bytes. The number of lines and samples are entered in the annotation file as slc_amp.set_rows and slc_amp.set_cols respectively. There is a separate file for each polarization channel (HH, HV, VH, and VV). The pixel spacing in meters is given in the annotation file by slc_amp.row_mult and slc_amp.col_mult for the azimuth and range directions, respectively. The projection of the data is in the natural slant range projection. The geographic coordinates of the data are defined by the " Peg position and heading ", and by the cross track and along track offset of the upper left pixel (given by set_plat, set_plon, and set_phdg, and slc_amp.row_addr and slc_amp.col_addr in the annotation file). The byte order is little endian. The units of the data are linear radar amplitude (rather than dB units).

    The four complex SLC files correspond to the measurement of the scattering matrix:

    Shh
    Shv
    Svh
    Svv

    MLC data:

    The MLC is a pure binary file with no header bytes. Three of the files are complex floating point, 8 byte per pixel. These complex products are derived from the average (usually 3 pixels in range, and 12 pixels in azimuth, given precisely by " Number of Range Looks in MLC " and "Number of Azimuth Looks in MLC" in the annotation file) of the product of each SLC pixel and correspond to:

    ShhShv*
    ShhSvv*
    ShvSvv* 

    Three of the files are real floating point, 4 bytes per pixel. These real powers are derived from the average (usually 3 pixels in range, and 12 pixels in azimuth, given precisely by " Number of Range Looks in MLC " and "Number of Azimuth Looks in MLC" in the annotation file) of the product of each SLC pixel and correspond to:

    ShhShh*
    ShvShv*
    SvvSvv*

    The number of lines and samples are entered in the annotation file as mlc_mag.set_rows and mlc_mag.set_cols respectively. There is a separate file for each product (HHHH, HVHV, VVVV, HHHV, HHVV, HVVV). The pixel spacing in meters is given in the annotatipon file by mlc_mag.row_mult and mlc_mag.col_mult for the azimuth and range directions, respectively. The projection of the data is in the natural slant range projection. The geographic coordinates of the data are defined by the "Peg position and heading", and by the cross track and along track offset of the upper left pixel (given by set_plat, set_plon, and set_phdg, and mlc_mag.row_addr and mlc_mag.col_addr in the annotation file). The byte order is little endian. The units of the data are linear radar power (rather than dB units).

    GRD data:

    The grd files consists of three real floating point, 4 bytes per pixel, and three complex floating point, 8 bytes per pixel files. The number of lines and samples may be found in the annotation file and are given by grd_mag.set_rows and grd_mag.set_cols respectively. The grd files contain projected multi-looked data for crossproducts HHHH, HVHV, VVVV, HHHV, HVHV, and HVVV:

    ShhShv*
    ShhSvv*
    ShvSvv*
    ShhShh*
    ShvShv*
    SvvSvv*

    in linear power units rather than db. The byte order is little endian. The data is in an equiangular coordinate system in which each line and pixel increments in latitude and longitude by grd_mag.row_mult and grd_mag.col_mult degrees from the upper left corner coordinate given by grd_mag.row_addr and grd_mag.col_addr

    UAVSAR projects slant range images to ground range using the backward projection method. An equiangular grid is found with latitude and longitude boundaries that cover the entire slant range image. For each point on the ground range grid, the corresponding indices are calculated on the multilooked slant range image. The data value closest to the coordinates pointed by the calculated slant range indices is assigned to the point on the ground range grid.

    These files are co-registered to the HGT file. 

    HGT data:

    The height file is a pure binary real*4 floating point file where the number of lines and samples may be found in the annotation file and are given by hgt.set_rows and hgt.set_cols respectively. This height file contains the values of elevation used to project the slant range data to the Earth's surface. The value of the ground elevation is given in meters. The datum is given by "DEM Datum" in the annotation file. The source of the DEM is given by "DEM source" in the annotation file. The data is in an equiangular coordinate system in which each line and pixel increments in latitude and longitude by hgt.row_mult and hgt.col_mult degrees from the upper left corner coordinate given by hgt.row_addr and hgt.col_addr

    This file is co-registered to the GRD files.

    Annotation file:

    The annotation file (.ann) is a keyword/value ASCII file in which the value on the right of the equals sign corresponds to the keyword on the left of the equals sign. The number of keywords may change with time, so the line number should not be assumed to be constant for any given keyword. In addition, the spacing between keywords and values may change. The units are given in parenthesis between the keyword and equal sign, and may change from annotation file to annotation file and within each annotation file. Comments are indicated by semicolons (;), and may occur at the beginning of a line, or at the middle of a line (everything after the semicolon on that line is a comment). The length of each text line is variable, and ends with a carriage return. There may be lines with just a carriage return or spaces and a carriage return.

    When using mdx to display the data files, use the corresponding display parameters in the annotation file. Use mlc_pwr to display the three real (4 byte per pixel) MLC data: HHHH, HVHV, and VVVV. Use mlc_mag and mlc_phase to display the three complex (8 byte per pixel) MLC data: HHHV, HHVV, and HVVV. Similarly, use grd_pwr to display real (4 byte per pixel) GRD data. Use grd_mag and grd_phase to display complex (8 byte per pixel) GRD data. 

    KML/KMZ file:

    The kml/kmz files are representations of the GRD data in Keyhole Markup Language. These files can be displayed in applications like Google Maps and Google Earth. The kml files contain low resolution image while the kmz files contain full resolution image (when zoomed in). The PolSAR kml/kmz files use the following color code:

    Red - ShhShh*
    Green - ShvShv*
    Blue - SvvSvv*

    Calibration of the data:

    Please see the calibration page for documentation on calibration of the data.

    Repeat-pass interferometry product data format

    From https://uavsar.jpl.nasa.gov/science/documents/rpi-format.html

    The format of the following files are described:

    • SLC files (.slc): calibrated single look complex files for each flight track (track 1, T1; and track 2, T2), floating point format, little endian, 8 bytes per pixel, corresponding to the same element of the scattering matrix. These files are available by request, but are not normally included in the data distribution.
    • AMP files (.amp1 and .amp2): calibrated multi-looked amplitude products, one file per repeat track, floating point format 4 bytes per pixel, little endian.
    • INT files (.int): interferogram product, one file per pair of repeat tracks, complex floating point format 8 bytes per pixel, little endian.
    • UNW files (.unw): unwrapped interferometric phase product, one file per pair of repeat tracks, floating point format 4 bytes per pixel, little endian.
    • COR files (.cor): interferometric correlation product, one file per pair of repeat tracks, floating point format 4 bytes per pixel, little endian.
    • GRD files (.grd): interferometric products projected to the ground in simple geographic coordinates (latitude, longitude). There is a fixed number of looks for each pixel. Floating point or complex floating point, little endian, 8 or 4 bytes per pixel.
    • HGT file: the DEM that the imagery was projected to, in the same geographic coordinates as the ground projected files. Floating point (4 bytes per pixel), little endian, ground elevation in meters.
    • KML and KMZ files (.kml or .kmz): these files allow you to view a representation of their corresponding file type in Google Earth or similar software.
    • PNG files (.png): these are representations of the corresponding products in standard PNG Format.
    • ANN file (.ann): a text annotation file with metadata. Example

    UAVSAR RPI File Naming Convention

    Each filename consists of the following components, separated by underscores:

    Example:
    SanAnd_26501_09083-010_10028-000_0174d_s01_L090HH_01.amp1.grd

    SanAnd – Site name
    265 - Heading of UAVSAR in flight for both tracks
    01 – Counter number set during planning

    Track 1

    Year - 09
    Nth UAVSAR flight in the year above (83rd flight in 2009) - 083
    Nth datatake during the flight (11th data take in flight 83) - 010

    Track 2

    Year - 10
    Nth UAVSAR flight in the year above (28th flight in 2010) - 028
    Nth datatake taken during the flight. Count starts at zero (1st data take) - 000


    Number of days between Track 1 and Track 2 - 174d
    Arbitrary ID - s01
    L-band - L
    Angle pointing from flight heading (steering angle) - 090
    Polarization, transmit/receive - HH
    Processing version number - 01
    Data type is AMP for Track 1 - .amp1
    Data is geocoded - .grd

    Formation of Interferometric Products:

    Prior to creating interferometric products, the SLC images from both tracks are co-registered to each other using GPS data and the data itself to estimate and compensate for the variable motion between the tracks.

    The single look complex (SLC) data for each track is summed in range and azimuth by the number of looks specified in the annotation file ("Number of Looks in Range" and "Number of Looks in Azimuthz") (typically 3 looks in range and 12 looks in azimuth), divided by the product of the number of looks in range and azimuth, and output as the amp1 and amp2 files.

    The interferogram in the .int file is formed by multiplying the single look complex image from track 1 times the complex conjugate of the single look complex image from track 2. The resulting complex values are then summed in range and azimuth according to the desired number of looks in the range and azimuth direction, with each pixel then divided by the product of the the number of azimuth looks and the number of range looks.

    The correlation file .cor is formed by dividing the interferogram values (the .int file) by the product of the multilooked amplitude values for track 1 and track 2 (the .amp1 and .amp2 files).

    The unwrapped interferometric phase file UNW (the .unw file) is obtained by applying the Goldstein/Werner method on the interferogram: Goldstein, R. M. and Werner, C. L., 1998. Radar interferogram filtering for geophysical applications. Geophysical Research Letters, 25(21):4035-4038.

    Data format description

    SLC data: 

    The SLC is a pure binary file (complex floating-point, 8 bytes per pixel) with no header bytes. The number of lines and samples are entered in the annotation file as *not currently in annotation file* and *not currently in annotation file* respectively. There is a separate file for each polarization channel (HH, HV, VH, and VV). The pixel spacing in meters is given in the annotation file by *not currently in annotation file* and *not currently in annotation file* for the azimuth and range directions, respectively. The projection of the data is in the natural slant range projection. The geographic coordinates of the data are defined by the " Peg position and heading ", and by the cross track and along track offset of the upper left pixel (given by Slant Range Data at Near Range, and Slant Range Data Starting Azimuth in the annotation file). The byte order is little endian. The units of the data are linear radar amplitude (rather than db units).

    These files are available by request, but are not normally included in the data distribution.

    The four complex SLC files correspond to the measurement of the scattering matrix:

    Shh
    Shv
    Svh
    Svv

    AMP data:

    The AMP files for track 1 and track 2 are pure binary files with no header bytes. They are floating point, 4 byte per pixel. These products are derived from the average (usually 3 pixels in range, and 12 pixels in azimuth, given precisely by " Number of Looks in Range" and "Number of Looks in Azimuth " in the annotation file) of the SLC values from the two tracks. They are in linear amplitude, not power units.

    The number of lines and samples are entered in the annotation file as " Slant Range Data Azimuth Lines" and " Slant Range Data Range Samples" respectively. The pixel spacing in meters is given in the annotation file by " Slant Range Data Azimuth Spacing" and " Slant Range Data Range Spacing" for the azimuth and range directions, respectively. The projection of the data is in the natural slant range projection. The geographic coordinates of the data are defined by the "Peg position and heading", and by the cross track and along track offset of the upper left pixel (given by Slant Range Data at Near Range, and Slant Range Data Starting Azimuth in the annotation file). The byte order is little endian. The units of the data are linear radar amplitude (rather than db units). For the interferogram products, no cross talk correction is applied.

    INT data:

    There is one .int file per pair of tracks. This file is a pure binary file with no header bytes. It is complex floating point format, 8 bytes per pixel. The byte order is little endian.

    UNW data:

    There is one .unw file per pair of tracks. This file is a pure binary file with no header bytes. It is floating point format, 4 bytes per pixel. The byte order is little endian.

    COR data:

    There is one .cor file per pair of tracks. This file is a pure binary file with no header bytes. It is floating point format, 4 bytes per pixel. The byte order is little endian.

     GRD data:

    The grd files consists of the same values as described above, except they are orthorectified to the DEM used in processing (the HGT file). They have the same number of bytes per pixel as before, but now the number of lines and samples are now indicated in the annotation file as " Ground Range Data Latitude Lines" and " Ground Range Data Latitude Samples" . The pixel spacing is now in degrees, and is given by " Ground Range Data Latitude Spacing" and " Ground Range Data Longitude Spacing" in the annotation file. The upper left coordinate of the file is given by " Ground Range Data Starting Latitude" and " Ground Range Data Starting Longitude" in the annotation file.

    UAVSAR projects slant range images to ground range using the backward projection method. An equiangular grid is found with latitude and longitude boundaries that cover the entire slant range image. For each point on the ground range grid, the corresponding indices are calculated on the multilooked slant range image. The data value closest to the coordinates pointed by the calculated slant range indices is assigned to the point on the ground range grid.

    These files are co-registered to the HGT file.

    HGT data:

    The height file is a pure binary floating point file, 4 bytes per pixel, where the number of lines and samples may be found in the annotation file and are given by Ground Range Data Latitude Lines and Ground Range Data Latitude Samples respectively. This height file contains the values of elevation used to project the slant range data to the Earth's surface. The value of the ground elevation is given in meters. The datum is given by "DEM Datum" in the annotation file. The source of the DEM is given by "DEM source" in the annotation file. The data is in an equiangular coordinate system in which each line and pixel increments in latitude and longitude by Ground Range Data Latitude Spacing and Ground Range Data Longitude Spacing degrees from the upper left corner coordinate given by Ground Range Data Starting Latitude and Ground Range Data Starting Longitude

    Because there are few areas for which a DEM exists that is comparable in resolution to the UAVSAR imagery, the DEM that the UAVSAR data is projected to is interpolated to the pixel spacing of the UAVSAR data. In some cases, the known DEM is much worse resolution than that of UAVSAR, and therefore errors in projection may occur.

    This file is co-registered to the GRD files.

    Annotation file:

    The annotation file (.ann) is a keyword/value ASCII file in which the value on the right of the equals sign corresponds to the keyword on the left of the equals sign. The number of keywords may change with time, so the line number should not be assumed to be constant for any given keyword. In addition, the spacing between keywords and values may change. The units are given in parenthesis between the keyword and equal sign, and may change from annotation file to annotation file and within each annotation file. Comments are indicated by semicolons (;), and may occur at the beginning of a line, or at the middle of a line (everything after the semicolon on that line is a comment). The length of each text line is variable, and ends with a carriage return. There may be lines with just a carriage return or spaces and a carriage return.

    Calibration of the data:

    Please see the calibration page for documentation on calibration of the data. 


    6. AIRSAR (data format)

    POLSAR and TOPSAR Headers

    All AIRSAR data files start with 3-4 header records. 

    • First header: general information about data file including # of lines and samples and offset to the first data record
    • Parameter header: information specific to the scene 
    • Calibration header: information on data calibration 
    • DEM header: only present for TOPSAR data; contains the elevation offset and elevation increment needed to translate the integer*2 values to elevations in meters 

    POLSAR Data

    POLSAR Data Mode

    The POLSAR operating mode collects twelve channels of data, four in each of the three frequencies of AIRSAR: P-, L-, and C-band.  The four data channels are:

    HH horizontally polarized transmit wave, horizontally polarized receive wave 
    HV horizontally polarized transmit wave, vertically polarized receive wave 
    VH vertically polarized receive wave, horizontally polarized receive wave 
    VV vertically polarized receive wave, vertically polarized receive wave   

    POLSAR Data Files:

    Naming Convention

    Example:
    cm4212_l.dat

      • Compressed Stokes matrix format - cm. Option: SY = synoptic 
      • Unique product number - 4212
      • L-band data - L. Options - C, L, P.
        • Due to FCC restrictions since 1994, P-band data are not included for POLSAR datasets collected at 40 MHz bandwidth over sites in the United States

    Data Format
    Compressed Stokes matrix data in slant range. File Size (10 km) is 15 Mbytes. 

    CM data are oriented so that each pixel sample is decreasing azimuth (along track) and each pixel line is of increasing range (cross-track).

    POLSAR Files

    Example set:
    cm4212_c.dat
    cm4212_l.dat
    cm4212_p.dat
    cm4212.gif
    cm4212_meta.airsar
    hdo4212.log

    TOPSAR Data

    TOPSAR Data Modes of Operation

    XTI1 - Generates a C-band DEM along with L- and P-band polarimetry
    XTI2 - Generates a C-band and an L-band DEM, along with P-band polarimetry
    (see exception below for when P-band data will not be present)

    TOPSAR data are processed on the AIRSAR Integrated Processor (ver. 5.1 or ver. 6.1). 

    TOPSAR Data Files

    Each TOPSAR scene typically contains:

        • 4 or 8 DEM (C-band or C-band and L-band) and related data files
        • 1 or 2 Polarimetric data files (see note below for exception)

    They have the following files:

    DEM Data (C-band, maybe L-band)
    c.vvi2 - C-band VV polarization only   - integer2 (signed 16 bit)
    demi2 - C-band DEM                             - integer2 (signed 16 bit)
    .corgr - Correlation coefficient map    - byte file  
    incgr - Local incidence angle map       - byte file  

    Polarimetric Data 
    l.datgr  - L-band polarimetry compressed Stokes matrix
    p.datgr - P-band polarimetry compressed Stokes matrix

    Note: Due to FCC restrictions, since 1994, P-band data are not included for TOPSAR datasets collected at 40 MHz bandwidth over sites in the United States.

    Naming Convention

    Example:
    ts1745_p.datgr

    • TOPSAR - ts
    • Unique product number - 1745
    • P-band data. - P. Options - C, L, P.
      • Due to FCC restrictions since 1994, P-band data are not included for POLSAR datasets collected at 40 MHz bandwidth over sites in the United States
    • Data projected in ground range - .datgr

    All TOPSAR data, including any polarimetric data collected in a TOPSAR mode, will be projected in the ground range.

    TOPSAR Data Conversions
    Data collected since 1993 are processed using Version 5.1 and Version 6.1. 

    Note that the integer*2 data will need to be converted using the following equations:

    Convert demi*2 data to elevations in meters:
    hs = (elevation increment) * DN + (elevation offset)

        • Elevation increment and offset are found in the DEM header record
        • DN is the integer*2 (signed) number from the .demi2 data file

    Convert vvi*2 data to radar cross sections
    sigma naught =(DN**2)/(General Scale Factor GFS)

        • DN is the integer*2 (signed) number as the amplitude (linear value) from the .vvi2 data file
        • GSF is in the second field of the Calibration Header. 
        • Note that the GSF = 10**6 

    Polarimetric data collected in the TOPSAR mode are read the same way as POLSAR data. 

    Get SAR Data

    Get SAR Data

    Select and download SAR data online using Vertex.

    Use the ASF API for downloading SAR data via a command line.