IMPORTSAR

Description

IMPORTSAR imports the specified SAR (POLSAR) data set. In particular, IMPORTSAR should be used for getting SAR data into pipes when using Modeler's canvas mode. IMPORTSAR can be the starting point for SAR processing workflows. Both image data and metadata can be imported. The entire image can be imported, or you may specify a rectangular subset window of data to import. The matrix format is automatically selected according to the data contained in the image. The physical quantity, represented by pixel values, can be specified as sigma, beta, or gamma only for RADARSAT-2 and ASAR. The imported image can then be converted to another matrix format using PSCONV.

IMPORTSAR is a cross between Modeler's regular IMPORT module and the SARINGEST function. IMPORTSAR, unlike IMPORT, is specifically designed to handle SAR data and should be used for all SAR data, especially scenes stored as complex channels. The difference between IMPORTSAR and SARINGEST is that IMPORTSAR has a variety of output ports whereas SARINGEST outputs everything to a single 'any' port.

Parameters

Name	Type	Length	Value range
Output: Output SAR image *	Raster port	1 -
OutputGCP: Output GCP segment	Raster port	0 -
OutputText: Output text segment	Text port	0 -
OutputOrbit: Output satellite orbital ephemeris segment	ORB port	0 -
OutputRPC: Output rational function segment	BIN port	0 -
OutputIncAngle: Output SAR incident angle segment	Array port	0 -
File *	String	1 -
Input window	Integer	0 - 4	Xoffset, Yoffset, Xsize, Ysize
Data calibration	String	0 - 1	Sigma Nought \| Beta Nought \| Gamma Nought \| None Default: None

* Required parameter

Parameter descriptions

Output: Output SAR image

Optionally specifies the output raster port to receive the SAR image data.

OutputGCP: Output GCP segment

Optionally specifies the output segment to receive the ground control points.

OutputText: Output text segment

Optionally specifies the output text segment, which will contain mainly metadata information about the scene.

OutputOrbit: Output satellite orbital ephemeris segment

Optionally specifies the output segment to receive the satellite orbital ephemeris layer.

OutputRPC: Output rational function segment

Optionally specifies the output segment to receive the rational function layer.

OutputIncAngle: Output SAR incident angle segment

Optionally specifies the output segment to receive the incidence angle array segment.

File

Specifies the name of the file that contains the input SAR imagery to be ingested. For SAR data sets distributed in multiple files, use the 'key file' name, as described below.

For each supported sensor, the general form of the key file name is indicated. For more information about the retrieved data for each product, refer to the help topics for specific sensors, in GDB file formats > Supported file formats in the Technical Reference section of the Online Help. The asterisk (*) in the file name indicates a (sensor-dependent) variable number of characters. The number symbols (#) in CV-580 file names indicate the line and pass number, respectively, of the given data set.

For the following sensors, specify the indicated files as the input file:

AIRSAR aboard a NASA DC-8 aircraft: specify the CM*.dat file
ASAR aboard the ESA ENVISAT satellite: specify the ASA_AP*.N1 file
Convair 580 (or CV-580) aboard a CCRS Convair 580 aircraft: specify one of the l#p#hhpolgasp.hdr, l#p#hvpolgasp.hdr, l#p#vhpolgasp.hdr, or l#p#vvpolgasp.hdr files
RADARSAT-2 (and simulated RADSARSAT-2): specify the product.xml file
SIR-C aboard the NASA Space Shuttle Endeavour: specify the pr*_ldr_ceos file
ERS and RADARSAT-1: specify the DAT_01.001 file
PALSAR: specify the IMG-*-ALPSR*-*.* (JAXA format) or DAT_01.001 (ERSDAC format) file
Cosmo-Skymed: specify the CSKS1_*.h5
TerraSAR-X/TanDEM-X: specify the *.xml file
UAVSAR: specify the *.ann file

Input window

Specifies the raster window (Xoffset, Yoffset, Xsize, Ysize) that is read from the input image. If this parameter is not specified, the entire image is processed by default.

Xoffset, Yoffset define the upper-left starting pixel coordinates of the window. Xsize is the number of pixels that define the window width. Ysize is the number of lines that define the window height.

Data calibration

Specifies the type of radiometric calibration applied. This defines the physical quantity that the imported pixels will represent, either Sigma Nought, Beta Nought, or Gamma Nought. The default is none.

This setting applies only for RADARSAT-2, ASAR, and UAVSAR images. The calibration is applied based on the coefficients provided in the scene.

Details

IMPORTSAR should be used to get SAR, especially complex SAR, data into Modeler pipes to allow further processing. The output pipes will be filled depending on the input scene file.

The matrix type depends on the content of input data, as described below. Each real matrix element is stored in one channel; each complex matrix element is stored in a single complex channel containing the real and imaginary components of the complex number. All values are stored as floating point numbers. All channels at a pixel are combined to yield the POLSAR matrix representation of the recorded signal at this pixel. For detected data, IMPORTSAR determines the output bit depth and channel type from the input bit depth.

Imported data products

The supported SAR-data products for each sensor are listed herein. For each sensor, the products are grouped by their POLSAR-matrix representations written to the output file.

The following data products are imported for the AIRSAR sensor [1]:

As a symmetrized covariance matrix C3r3c:
- MLC: Multilook complex, standard quad-polarization
  
  The data is imported as six channels, which represent the six independent elements of the C3r3c matrix.
The output AIRSAR file also has an array segment that contains an incident angle value (in degrees) for each range sample location.

The following data products are imported for the ASAR sensor [2]:

As an incomplete covariance matrix c2r:
- ASA_APG_1P: Alternating Polarization mode, ellipsoid geocoded
- ASA_APM_1P: Alternating Polarization mode, medium resolution
- ASA_APP_1P: Alternating Polarization mode, precision
The data is imported as two channels, which represent the two independent real-valued elements of the c2r matrix.
As an incomplete Sinclair scattering matrix s2c:
- ASA_APS_1P: Alternating Polarization mode, single look complex
  
  The data is imported as four channels, which represent the real and imaginary components of the two independent elements of the s2c matrix.
  
  Importing the ASA_APS_1P data requires an external calibration file ASA_XCA_AX. It is recommended that you acquire the file with the distributed data or download it from the ESA archive [5].
The output ASAR files also have an array segment that contains an incident angle value (in degrees) for each range sample location and a GCP segment with ground control points for nominal georeferencing.

The following data products are imported for the CV-580 sensor [3]:

As a non-symmetrized Sinclair scattering matrix s4c:
- SLC-Q: Single look, complex, standard quad-polarization
  
  The data is imported as four channels, which represent each component of the four independent complex elements of the s4c matrix.
As a symmetrized covariance matrix C3r3c:
- MLC-Q: Multilook complex, standard symmetrized quad-polarization
  
  The data is imported as six channels, which represent the three real and three complex independent elements of the C3r3c matrix.

The following RADARSAT-2 data products are imported [4]:

As a non-symmetrized Sinclair scattering matrix s4c:
- SLC-FQ: Single look, complex, fine quad-polarization.
- SLC-SQ: Single look, complex, standard quad-polarization
  
  The quad-polarization, slant-range SLC data products imported as four channels, which represent each component of the four independent complex elements of the s4c matrix.
As an incomplete Sinclair scattering matrix s2c:
- SLC-FD: Single look, complex, fine dual-polarization
- SLC-SD: Single look, complex, standard dual-polarization
- SLC-WD: Single look, complex, wide dual-polarization
  
  The dual-polarization slant-range SLC data is imported as two channels, which represent each component of the two independent elements of the s2c matrix.
As an incomplete non-symmetrized covariance matrix c4r:
- SGX-FQ: SAR georeferenced extra, fine quad-polarization
- SGX-SQ: SAR georeferenced extra, standard quad-polarization
- SSG-FQ: Systematic geocorrected fine quad-polarization
- SSG-SQ: Systematic geocorrected standard quad-polarization
- SPG-FQ: Precision geocorrected fine quad-polarization
- SPG-SQ: Precision geocorrected, standard quad-polarization
  
  The quad-polarization ground-range or geocorrected data is imported as four channels, which represent the real-valued diagonal elements of the matrix c4r.
As an incomplete covariance matrix c2r:
- SGX-FD: SAR georeferenced, extra, fine dual-polarization
- SGX-SD: SAR georeferenced, extra, standard dual-polarization
- SGX-WD: SAR georeferenced, extra, wide dual-polarization
- SGF-FD: SAR georeferenced, fine, fine dual-polarization
- SGF-SD: SAR georeferenced, fine, standard dual-polarization
- SGF-WD: SAR georeferenced, fine, wide dual-polarization
- SGC-FD: SAR georeferenced, coarse, fine dual-polarization
- SGC-SD: SAR georeferenced, coarse, standard dual-polarization
- SGC-WD: SAR georeferenced, coarse, wide dual-polarization
- SSG-FD: Systematic geocorrected, fine dual-polarization
- SSG-SD: Systematic geocorrected, standard dual-polarization
- SSG-WD: Systematic geocorrected, wide dual-polarization
- SPG-FD: Precision geocorrected, standard dual-polarization
- SPG-SD: Precision geocorrected, standard dual-polarization
- SPG-WD: Precision geocorrected, wide dual-polarization
  
  The dual-polarization ground-range or geocorrected data is imported as two channels, which represent the real-valued diagonal elements of the matrix c2r.
Output files for all slant-range and ground-range simulated RADARSAT-2 data products (SLC, SGX, SGF, and SGC) also have an array segment that contains an incident angle value (in degrees) for each range sample location.

The following data products are imported for the RISAT-1 sensor:

As an incomplete Sinclair scattering matrix s2c:
- FRS-1: Single look, complex, dual-polarization
- FRS-1: Single look, complex, compact-polarization
- FRS-2: Single look, complex, compact-polarization
- MRS-1: Single look, complex, compact-polarization
- MRS-1: Single look, complex, dual-polarization
- CRS-1: Single look, complex, dual-polarization
- CRS-1: Single look, complex, compact-polarization
- HRS-1: Single look, complex, dual-polarization
- HRS-1: Single look, complex, compact-polarization
As a Sinclair scattering matrix s4c:
- FRS-2: Single look, complex, full-quad-polarization

The following data products are imported for the SIR-C sensor [1]:

As a non-symmetrized Sinclair scattering matrix s4c:
- SLC-Q: Single look, complex, standard quad-polarization
  
  The quad-polarization, slant-range SLC data is imported as four channels, which represent each component of the four independent complex elements of the s4c matrix.
As an incomplete Sinclair scattering matrix s2c:
- SLC-D: Single look, complex, dual-polarization
  
  The dual-polarization slant-range SLC data is imported as two channels, which represent each component of the two independent elements of the s2c matrix.
As a symmetrized covariance matrix C3r3c:
- MLC-Q: Multilook, complex, quad-polarization
  
  The quad-polarization, slant-range MLC data is imported as six channels, which represent the six independent elements of the C3r3c matrix.
As an incomplete covariance matrix c2r1c:
- MLC-D: Multilook, complex, dual-polarization
  
  The dual-polarization, slant-range MLC data is imported as three channels, which represent the two real and one complex element of the c2r1c matrix.

Metadata

In addition to image and segment data, the algorithm extracts metadata related to SAR processing and writes it to the output file. There are two levels of metadata: file and channel.

At the file level, SAR metadata contains information that relates to the data set as a whole, including:

SensorModelName: Description of the sensor; for example RADARSAT-2
SensorType: Always SAR
Product_Type: Imported data product; for example, SLC for RADARSAT-2 or ASA_APM_1P for ASAR
Matrix_Type: Matrix stored on file; for example, s4c or c2r
Acquisition_Type: Optional detailed information related to the image; for example, standard quad-polarization for RADARSAT-2 or alternating polarization for ASAR
SAR_Calibration: Physical quantity represented by pixel values; for example, sigma0
MicrowaveBand: SAR band of the image; for example x or x
Polarizations: List of polarizations of the data in the image; for example, HH, HV. Each polarization is represented by two characters. The first character specifies the transmit polarization, the second specifies the receive polarization.
NumLooks: Nominal number of SAR looks for each pixel
NumRangeLooks: Number of SAR looks, in range direction, for slant-range images
NumAzimuthLooks: Number of SAR looks, in azimuth direction, for slant-range images

At the channel level, metadata for polarimetric data identifies the matrix element stored in the channel:

Matrix_Element: Describes the row and column position of the element in the matrix.

For example, with a data set stored as an s4c matrix, the first channel is identified as _1_1 and the second channel is identified as _1_2.

References

[1]. Chapman, B. SIR-C Data Compression Software User Guide, NASA JPL D-11427, Revision 2.0. June 1994; http://jpl.nasa.gov.

[2]. European Space Agency, ASAR Product Handbook, September 2004; http://envisat.esa.int/pub/ESA_DOC/ENVISAT/ASAR/asar.ProductHandbook.1_3.pdf.zip.

[3]. Wind, A.F. and K.P. Murnaghan. CV-580 PolGASP Format Definition, CCRS-TN-2002-025. Canada Centre for Remote Sensing, November 24, 2004.

[4]. MDA, RADARSAT-2 Product Format Definition, RN-RP-51-2713, Issue 1/5, 2003.

[5]. ESA, ASAR Auxiliary Data Files. Available at http://earth.esa.int.

Environments	MODELER
Batch Mode	Yes
Quick links	Description :: Parameters :: Parameter descriptions :: Details :: References :: Related