Alaska Satellite Facility
Delivering Remote Sensing Data Since 1991

Note: Although some answers on this page are outdated, users report they are useful enough to retain while ASF works on updates. Users may contact ASF with further questions (contact information at bottom of page).

Table of Contents

Documentation and Terminology
Where do I find the documentation for MapReady?
Where can I find the details about the satellite metadata?
What do the different levels in optical ALOS data mean?
Can you tell me the difference between pixel spacing and pixel size of SAR image?
In a file it is said that for PALSAR SLC polarimetric image, its pixel spacing is 9.36 m in range direction, and it is 1.77 m in azimuth direction. Is it right?
What is Faraday rotation?
Software and Functionality
What data formats are currently supported?
What CEOS flavors are supported?
What calibration schemes are supported?
What Linux operating systems can I use to build MapReady from source?
Does MapReady work on a Mac?
How do I launch a tool under Windows?
I am trying to process my data with MapReady and get a "permission denied" error. Why is that?
Is there a way to help the developers help troubleshooting a problem with MapReady?
Where do I find intermediate results?
What does "Temporarily keep intermediate files" mean?
Data Support and Metadata
What kind of SAR data does MapReady ingest?
What type of CEOS data is supported?
Does MapReady support CEOS data formats other than ASFs?
Can MapReady handle ScanSAR level zero data?
Does MapReady ingest ALOS Palsar Level 1.0?
Which types of optical ALOS data is supported by MapReady?
Does MapReady support Radarsat-2 data?
Does MapReady support SIR-C data?
I want to have a look at the CEOS metadata. How do I do that?
I have lot of SAR data to analyze. Is there a way to extract from such as corner coordinates for each scene?
Data Analysis
I want to do some analysis with my SAR data that requires parameters such as sigma0 and incidence angle. What type of data should I use?
I need to create a subset of my data. Which tool should I use?
How do I extract incidence angle information out of my data?
In what format can save subsets generated with asf_view?
Can I apply speckle filtering in MapReady?
Radiometry and Calibration
What is getting calibrated? The data or the processor?
I have three options for the radiometry to choose from? Which one do I need?
I have some calibrated SAR data but the value range (0 to 5) does not look right. Are these values in dB?
I want to know the average backscatter value of an area in dB. How do I do that?
I want to analyze my calibrated backscatter values in another software package. What export options should I choose?
I heard ERS-2 data sets have a gain loss problem. Can I correct my ERS-2 data for that?
Polarimetry
What kind of data do I need for polarimetric processing in MapReady?
I have some dual-pol data. Can I use those for polarimetric processing?
Is there any polarimetric decomposition that works with ALOS Palsar level 1.5 data?
What do the colors in the Pauli decomposition mean?
What parameters are calculated for the Cloude-Pottier decomposition and what do they mean?
Digital elevation models (DEMs) and terrain correction
What kind of digital elevation models (DEMs) should I use for terrain correction?
My DEM downloaded from the National Map Seamless Server does not work in the terrain correction of MapReady?
Do you know any software that will generate a DEM from an ALOS Prism triplet?
How many ground control points (GCPs) does PCI Geomatica take for the generation of a Prism DEM?
Is there any description how the PCI generates a DEM from ALOS Prism data?
Is it possible to run MapReady for AirSAR data terrain correction?
I am having trouble with one PALSAR scene in Mapready, it won't run with the terrain correction application.
What kind of vertical datum is required for DEM in MapReady for terrain correction and geocoding. Geoidal height (above mean sea level) or ellipsoidal height?
Are there cases when I should not terrain correct my data?
Is there a way to mask out area that should not be terrain corrected, e.g. big water bodies, or areas that are otherwise constantly moving, e.g. glaciers?
The matching of my SAR image and the simulated SAR image derived from the DEM fails, but I still see some offsets in the results. What can I do?
Why is the matching of the real image and the simulated image derived from the DEM done in slant range?
Geocoding and Export
What map projections are supported by MapReady?
I am not sure which map projection to use. What is the best projection for my project?
I see big geolocation errors when I am geocoding JERS data. What is wrong here?
Can I re-project data with MapReady?
Is there a difference in exporting an optical RGB image with the "True Color" or "False Color" instead of assigning the individual band in the "User Defined" option?
How can I change the size of my image during the processing?
Can I make sure that I keep my original pixel values during the geocoding?
I would like to mosaic some geocoded images. How do I go about that?
Interferometry
Where can I find Radarsat-1 interferometric baseline information?
Does the Radarsat-1 baseline information cover all Radarsat-1 data?
Can I do interferometric processing with MapReady?
SAR training processor
Can I use my own data in the SAR training processor?
In the SAR Training Processor, what the .txt, .meta, .in, and especially the .fmt mean?
Can I use ESA data with the SAR training processor?

Documentation and Terminology

Where do I find the documentation for MapReady?
In Windows the PDF version of the comprehensive manual is located in the 'Start' menu at 'Programs -> ASF tools -> MapReady'. In Linux the documentation is located in /usr/local/share/asf_tools/doc (assuming that the tools were installed by the system administrator).
Where can I find the details about the satellite metadata?
The ALOS production specifications for the different sensors are provided by JAXA:
For other data formats please see:

What do the different levels in optical ALOS data mean?
There are four levels of ALOS Avnir/Prism data:
  • level 0: raw data generated by every downlink segment and every band
  • level 1A: raw data extracted from level 0, expanded and generated lines
  • level 1B1: radiometrically corrected image
  • level 1B2R: geometrically corrected image, georeferenced (corner coordinates known in map projection)
  • level 1B2G: geometrically corrected image, geocoded to map projection

Can you tell me the difference between pixel spacing and pixel size of SAR image?
I would use the terms "pixel spacing" and "pixel size" interchangeably. The terms that usually mixed up are is "pixel size" and "resolution". Resolution refers to the size of the resolution cell on the ground, i.e. the area where the information in your pixel came from. The pixel size depends on what the processor does with that. Usually the pixel size is smaller, i.e. the processor oversamples the information that it has.

In a file it is said that for PALSAR SLC polarimetric image, its pixel spacing is 9.36 m in range direction, and it is 1.77 m in azimuth direction. Is it right?
SLC stands for single look complex, i.e. the image has not been multilooked. Therefore, you are dealing with pixels that are not square (yet). Regular detected products come with a square pixel size. If you look at the amplitude image from your SLC image, you will see that everything is stretched in azimuth direction. Depending on the type of polarimetric data (single-pol, dual-pol or quad-pol) you have a ratio of 1:8 or 1:4 to get to square pixel by multilooking.

What is Faraday rotation?
Faraday rotation is a rotation of the polarization vector of radio waves that propagated through the ionosphere. L-band SAR data such as ALOS Palsar data are most affected by this.


Software and Functionality

What data formats are currently supported?
This table summarizes the data formats:
FormatImportExportComments
CEOSx
Sky Telemetry Formatx
GeoTIFFx
AirSAR polarimetricx
AirSAR InSARx
TerraSAR-Xx
Gammax
PolSARprox
ALOS mosaicx
Vexcel Plainx
BILxhas not been tested lately
GridFloatxhas not been tested lately
JAXA L0 (optical)x
ENVIxxingest in asf_view
TIFFx
JPEGx
PNGx
PGMx
ALOS browse imagexdirect conversion to JPEG

What CEOS flavors are supported?
This table summarizes the supported CEOS flavors:
FacilityProductsComments
ASF PPERS, RSAT, JERSJERS L0 to be verified
ASF SSPall products
EOCPalsar (level 1.1, level 1.5)single-, dual- and quad-pol
EOCPrism (1A, 1B1, 1B2R, 1B2G)1A and 1B1 only import
EOCAvnir (1A, 1B1, 1B2R, 1B2G)1A and 1B1 only import
D-PAFRAW, SLC
I-PAFRAW, SLC
ESARAW, SLC
CDPFSLC, SGF, SGX, SSG, ScanSAR
RSIRAW, SGF, SGX, ScanSAR
CSTARSRAW, SLC, SGF, SGX, PRI, SSG, GEC, ScanSARwork in progress
BeijingRAW
TromsoSNA, SNB
WestfreughSNB
DeraPRI

What calibration schemes are supported?
This table summarizes the supported calibration schemes:
TypeCalibration projectionComments
ASFsigmalinear equation (includes noise floor)
ESAgammaconstant
ALOSsigmaconstant
CDPFgammarange dependent look up table

What Linux operating systems can I use to build MapReady from source?
You can probably compile the tools on any Linux system. We develop the tools on CentOS and Ubuntu machines (32-bit and 64-bit).

Does MapReady work on a Mac?
We managed to compile the command line tools on a Mac, but this operating system is currently not supported.

How do I launch a tool under Windows?
The graphical user interface in MapReady (ASF MapReady, ASF view, CEOS Metadata Viewer, Projection Coordinate Converter) are by default in the Start menu 'Programs -> ASF tools > MapReady'. The command line tools can be launched from the MS-DOS prompt. To open the MS-DOS prompt, you click 'Run' and type 'cmd'.

I am trying to process my data with MapReady and get a "permission denied" error. Why is that?
The most likely cause for this is that you are trying to process data that is on a DVD. By default, MapReady selects the output directory where the input data is. Since our data DVDs are read only, you don't have permission to write to them. As a minimum, you want to change the output directory that is located on a regular hard disk. Alternatively, you can copy the data from DVD to your computer before you do the processing.

Is there a way to help the developers help troubleshooting a problem with MapReady?
Most definitely. A screen capture of the exact error message is a good starting point. The log file of the problem run gives us even more information. The best way to even troubleshoot a problem yourself, besides looking at the log file, is to use the "Keep intermediates" option in the general settings of MapReady. The log file indicates the commands used in the processing flow with some indication what files were used. The more information we have, the easier it is to reproduce the problem on our end, in order to figure out what is wrong.

Where do I find intermediate results?
For processing each data set MapReady generates a temporary directory such as "ALPSRP106002960-P1.5_UD-08-Apr-2009_15-15-38". The directory name contains the name of the file and a time stamp when the data set was processed. This way you are not accidentally overwriting any previously processed results. Unless the user specifies that this directory is kept with the "Keep intermediates" option in the general settings, the directory is deleted.

What does "Temporarily keep intermediate files" mean?
Intermediate files are kept until program exit, or the file is removed from the "Completed Files" section, to allow viewing the intermediates after the processing has completed.


Data Support and Metadata

What kind of SAR data does MapReady ingest?
Data in CEOS and in Sky Telemetry Format (STF).

What type of CEOS data is supported?
MapReady supports three types of CEOS data. The CEOS level zero data is raw signal data that needs to run through a SAR processor before it can be visualized. CEOS single look complex (SLC) data is primarily used for SAR interferometry, as it contains both amplitude and phase information. CEOS level one data is the most commonly used for all other applications.

Does MapReady support CEOS data formats other than ASFs?
We have incorporated generic support for a number of other CEOS flavors. If you have a data set that does not ingest, please provide us with a data set, so that we enhance the ingest capabilities in future releases. This kind of effort progress as time permits.

Can MapReady handle ScanSAR level zero data?
The processing of ScanSAR raw data is not supported. The ScanSAR data consists of several bands (the numbers varies between three and five depending on the satellite) that are processed separately and then "stitched together". That is beyond the capabilities of our regular SAR processor.

Does MapReady ingest ALOS Palsar Level 1.0?
No, it doesn't. MapReady support starts with level 1.1 data.

Which types of optical ALOS data is supported by MapReady?
Only level 1B2 data are supported, regardless whether they are georeferenced or geocoded.

Does MapReady support Radarsat-2 data?
No, it does not.

Does MapReady support SIR-C data?
Not as this point.

I want to have a look at the CEOS metadata. How do I do that?
There are two ways of going about it. There is a graphical user interface that is located in the Windows 'Start' menu at 'Programs -> ASF tools -> CEOS metadata viewer'. From the command line you can start it by typing mdv. Alternatively, the command line tool metadata allows you to extract the individual CEOS records out of the leader file. They can also be saved as plain text files.

I have lot of SAR data to analyze. Is there a way to extract from such as corner coordinates for each scene?
You want to use is the convert2vector tool. With a larger number of files you want to use the '-list' option that reads the input from a text file that contain the list of files to be converted. The input format option would be 'leader' and the output format option would be 'csv'. That would dump the coordinates (and other relevant metadata) to a comma delimited ASCII text file. This is assuming that you want to parse the information to some other application. For visualization purposes you choose the output as KML or shape file.


Data Analysis

I want to do some analysis with my SAR data that requires parameters such as sigma0 and incidence angle. What type of data should I use?
This type of analysis requires detected (L1) data. Since the data is not geocoded yet, it still contains all the information about the viewing geometry.

I need to create a subset of my data. Which tool should I use?
There are two tools that generate subsets: trim and asf_view. If you just want to work with the pixel values of an image, trim is faster solution. If you want to have additional information such as geometric parameters for the subset, you want to use asf_view.

How do I extract incidence angle information out of my data?
After loading the image in asf_view, you can extract a subset for which you can save a number of values. In order to define the subset in the viewer, you place a crosshair for one of the corner points of your area of interest (left-click). Then you keep adding points to the polygons (ctrl-left-click).
The list of values that you can save for an image subset include
  • pixel values,
  • incidence angle,
  • look angle,
  • slant range,
  • time,
  • Doppler, and
  • scaled pixel values

In what format can save subsets generated with asf_view?
Subsets can be saved in the ASF internal format or a command delimited text files (CSV).

Can I apply speckle filtering in MapReady?
We have not implemented any speckle filters in MapReady, neither for regular nor for polarimeteric processing.


Radiometry and Calibration

What is getting calibrated? The data or the processor?
A SAR processor is calibrated when the coefficients required for accurate radiometry have been determined, but an image is calibrated only when those coefficients have been applied.

I have three options for the radiometry to choose from? Which one do I need?
It depends on what you want to do with the data.
  • Beta nought is essentially a ratio between the power that was sent from the antenna and the power that returned to the antenna. Beta nought is in the realm of slant range. This is typically used by engineers that care about the electronics of it all.
  • Sigma nought is the power returned to the antenna from the ground plane and is thus in the realm of ground range. Scientists tend to use this measure.
  • Gamma nought is typically used when calibrating the antenna. Since each range cell is equally distant from the satellite, near range and far range are equally as bright which is helpful in determining the antenna pattern.

I have some calibrated SAR data but the value range (0 to 5) does not look right. Are these values in dB?
The value range suggests that your values are in power scale. In order to get them into the dB scale, you would need to convert them:

dB = 10 * log10 (power scale)

A value range in power scale between 0 and 5 would be equivalent to a value range between -50 dB and 0 dB.

I want to know the average backscatter value of an area in dB. How do I do that?
You apply the calibration parameters by selecting the radiometry to be 'Sigma', 'Beta', or 'Gamma' and ingest the data. This will result in an image in power scale values. Do not scale the output to decibels. Average the values in the area of interest and convert the average value to dB, using this formula:

dB = 10 * log10 (power scale)

I want to analyze my calibrated backscatter values in another software package. What export options should I choose?
In order to ingest your data properly in any of the image processing and GIS software packages out there, you want to export your geocoded data into GeoTIFF format. That is probably the best supported format that contains all the relevant map projection information. In order to keep the full dynamic range and the original values you want to export the data as floating point data. So do not scale your data to byte values.

I heard ERS-2 data sets have a gain loss problem. Can I correct my ERS-2 data for that?
The ERS2 satellite has a known gain loss problem. All pixels in the image are scaled by a correction factor that is date-dependent. This is only applied to calibrated data.


Polarimetry

What kind of data do I need for polarimetric processing in MapReady?
You need fully polarimetric single look complex (SLC) data. For ALOS Palsar data that means level 1.1. Polarimetric AirSAR data is also supported.

I have some dual-pol data. Can I use those for polarimetric processing?
Dual-pol data is not supported for polarimetric processing within MapReady. However, this type of processing can be done in PolSARpro and ingested into MapReady after that.

Is there any polarimetric decomposition that works with ALOS Palsar level 1.5 data?
The only polarimetric decomposition that also works with detected imagery is Sinclair.

What do the colors in the Pauli decomposition mean?
Each color represents a different scattering mechanism (Red: even, Green: volume, Blue: odd).

What parameters are calculated for the Cloude-Pottier decomposition and what do they mean?
These parameters are calculated from the coherence matrix, which is calculated for each pixel. These parameters are ''entropy'', ''anisotropy'', and ''alpha''. Entropy is an indication of the degree of randomness in the scattering process. Low entropy means there is a single dominant scattering mechanism in that pixel; high entropy means multiple scattering mechanisms are present in the pixel. Anisotropy represents the relative importance of the non-dominant scatterers. When entropy is low, the anisotropy parameter means very little, but for high entropy it is a useful indication of the strength of the secondary scatters. Alpha can be used to identify what type of scatterer is the dominant one. When alpha is close to 0, single-bounce scattering (e.g., a rough surface) is dominant. For alpha near 90°, the dominant scatterer is double-bounce. Alphas in between these extremes represent a combination of both; at 45° we have equal amounts of both which usually corresponds to volume scattering.


Digital elevation models (DEMs) and terrain correction

What kind of digital elevation models (DEMs) should I use for terrain correction?
Generally the best source for DEMs is the [http://seamless.usgs.gov/ Shuttle Radar Topography Mission]. For the US, the data is available in 30 m spacing. For the rest of the world between 60 degrees Northern latitude and 56 degrees Southern latitude the data is available in 90 m spacing.

My DEM downloaded from the National Map Seamless Server does not work in the terrain correction of MapReady?
Once you've selected your area of interested and the download window pops up, make sure to click on the "Modify data request" link up top before you hit the download button. In the "The National Map Seamless Server Request Options Page" scroll down to your dataset and change the data format from ArcGRID to GeoTIFF. Then scroll to the bottom and click the "Save Changes & Return to Summary" button. Now you can click the download button and retrieve your GeoTIFF format DEM for terrain correction in MapReady.

Do you know any software that will generate a DEM from an ALOS Prism triplet?
PCI Geomatica is able to generate DEMs from Prism. It supports level 1B1 (preferred) and level 1B2R data.

How many ground control points (GCPs) does PCI Geomatica take for the generation of a Prism DEM?
PCI recommends six GCPs per CCD.

Is there any description how the PCI generates a DEM from ALOS Prism data?
You can download the [http://www.pcigeomatics.com/services/support_center/tutorials/pdf/dem_extraction_prism.pdf PCI tutorial].

Is it possible to run MapReady for AirSAR data terrain correction?
Our current implementation of the terrain correction does not support this. However, the geocoding of AirSAR data is supported.

I am having trouble with one PALSAR scene in Mapready, it won't run with the terrain correction application. With this particular image I get the error below:
"Correlated images failed to match!
Original fftMatch offset: (dx,dy) = 1080.027343750, -492.555908203
After shift, offset is: (dx, dy) = -1312.802612305, 476.835266113
The first thing terrain correction does is create a simulated SAR image from the DEM, and then use FFTs to match this simulated image with the image you're terrain correcting. For this FFT matching to work, there has to be some "relief" in the scene - mountains, hills, etc. Is the scene that is failing of a flat area, and the surrounding scenes contain the hilly areas? If this is the case, you can probably just skip terrain correction for that scene - and when geocoding, specify the average height of the area.

What kind of vertical datum is required for DEM in MapReady for terrain correction and geocoding. Geoidal height (above mean sea level) or ellipsoidal height?
Ellipsoidal height is what MapReady is looking for.

Are there cases when I should not terrain correct my data?
Terrain correction is usually not a good idea when the area of interest in very flat or does not have a lot of relief. In these cases you might consider geocoding the image to the average height.

Is there a way to mask out area that should not be terrain corrected, e.g. big water bodies, or areas that are otherwise constantly moving, e.g. glaciers?
MapReady can generate a water mask derived from a DEM, assuming the areas below a certain threshold (the default value is 1 m) is water. Other areas can be masked out based on a mask file that the user needs to supply.

The matching of my SAR image and the simulated SAR image derived from the DEM fails, but I still see some offsets in the results. What can I do?
You can manually measure what the offset is and apply those values in the "Skip co-registration" option.

Why is the matching of the real image and the simulated image derived from the DEM done in slant range?
The matching in original SAR geometry is the most straight forward way of estimating the offset.


Geocoding and Export

What map projections are supported by MapReady?
MapReady supports the following map projections for geocoding:
  • Universal Transverse Mercator (UTM)
  • Albers Conical Equal Area
  • Polar Stereographic
  • Lambert Conformal Conic
  • Lambert Azimuthal Equal Area

I am not sure which map projection to use. What is the best projection for my project?
Cylindrical projections work best in equatorial areas. The Universal Transverse Mercator (UTM) projection is the most commonly used one from this family of map projections. The distortions within the UTM projection are manageable as long as the projected area is not very large. Conic projections, commonly defined with two standard parallels, are often used in the mid-latitude regions. In this case, the Albers Conic Equal Area projection preserves area, while the Lambert Conformal Conic projection preserves angles. Azimuthal projections are mostly used in the polar regions. The Polar Stereographic projection and Lambert Azimuth Equal Area projection are well known representatives of this type of projection.

I see big geolocation errors when I am geocoding JERS data. What is wrong here?
The JERS satellite had at times issues with clock errors. These time errors lead sometimes to big offset in azimuth direction (flight direction). In order to remove this shift, you need to run the data through terrain correction. In the process the shift is determined by matching the real image with a simulated amplitude image derived from the reference DEM. If the area is too flat for regular terrain correction, you may need to measure the offset manually, and then use the 'Shift Geolocation' option in the External tab.

Can I re-project data with MapReady?
Yes, you can. By selecting geocode with a different map projection for already geocoded data, MapReady will re-project the data set.

Is there a difference in exporting an optical RGB image with the "True Color" or "False Color" instead of assigning the individual band in the "User Defined" option?
There actually is. The "True Color" and "False Color" option apply a 2-sigma contrast expansion to each individual channel before combining them to a color image. Any user defined color combination of channels leave the original pixel values in place.

How can I change the size of my image during the processing?
There are two ways of doing that. There is an external tool "Resample" that allows you to resize the image right after ingesting it, choosing a scale or dimension. Alternatively, you can geocode the image to a particular pixel size.

Can I make sure that I keep my original pixel values during the geocoding?
By default the geocoding will use a bilinear interpolation which changes the resulting pixel value as it takes a weighted average of four input pixels into account. In order to preserve the pixel values the "Resample" method needs to be changed to "Nearest neighbor". In case of the geocoding of polarimetric decompositions and classifications this is enforced automatically.

I would like to mosaic some geocoded images. How do I go about that?
This functionality is currently only available on the command line. However, there are two ways of doing it. The mosaic tool is geocoding the data and mosaicking at the same time. This would require to define all map projection parameters on the command line. The combine tool is probably more convenient for this purpose, as is does not require any map projection information. It is assumed that all input data is already in the same map projection. That, however, can easily be achieved by using MapReady for all the processing steps from ingesting the data to geocoding them. Both tools expect to see ASF internal format data. The results still would need to be exported to GeoTIFF format to be really useful.


Interferometry

Where can I find Radarsat-1 interferometric baseline information?
This information has been integrated into the URSA search and order interface. After searching data for the area of interest a link to the available baseline information is located in the upper right corner.

Does the Radarsat-1 baseline information cover all Radarsat-1 data?
The baseline information is only calculated for the data in the ASF data archive.

Can I do interferometric processing with MapReady?
MapReady does not support any interferometric processing. However, it supports the ingest of files (currently interferogram and coherence images) generated with the GAMMA software.


SAR training processor

Can I use my own data in the SAR training processor?
Yes you can. You will need to ingest the raw data in CEOS or STF format using ''asf_import'' on the command line or MapReady with only the 'Import data' option switched on.

In the SAR Training Processor, what the .txt, .meta, .in, and especially the .fmt mean?
The metadata file (.meta) is an ASCII file that contains most of the metadata needed for using the ASF software tools. It is created from the level zero CEOS leader file (.L), while converting the level zero data into ASF internal raw signal data. The ardop processor parameter file (.in) is an ASCII file that contains all relevant parameters used for the processing of a SAR image with the SAR training processor. It is created while level zero CEOS frame data into ASF internal raw signal data. It is updated as the processing continues. Each sample of SAR data is encoded as two bytes, containing the real and imaginary (I and Q) components of the echo. Window shift and antenna gain control values are provided to correct the antenna gain in order to avoid the saturation of parts of the image. The format of the data format file (.fmt) is ASCII.
Format:
<number of bytes per line of data> <number of header bytes per line>
<mean value of I samples> <mean value of Q samples>
<byte order in file: ’n’=i,q; ’y’=q,i>
[<ignored line>]
[<line1> <window shift (pixels)> <agc scale>]
[<line2> <window shift (pixels)> <agc scale>]
[...]

Example:
11232 0 ! Bytes per line, bytes per header.
15.500000 15.500000 ! i,q bias
n ! Flip i/q?
! Starting line #, Window Shift (pixels), AGC Scaling
0 4391.938 1
All these files are stored in ASCII format, so you can view them with any text editor.

Can I use ESA data with the SAR training processor?
Yes. You will need to ingest the level zero data to the ASF internal format using ''asf_import''.
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.