X-SAR Radar Layover/Shadow Mask and Incidence Angle Mask Product (GIM, held at DLR/DFD)Entry ID: DFD-X-SAR.SAR.GIM
Abstract: Mission Objective:
Please see the relevant SIR-C/X-SAR Mission description contained in the
references and as Supplementary Information for "sensor"(X-SAR).
There were two Missions with the following time frame:
- Space Shuttle Mission STS-59:
- Space Shuttle Mission STS-68:
... Stop_Date: 1994-10-11
Worldwide coverage and map prints are available on World Wide Web (see below).
Data Set Content:
The X-SAR geocoded image, with terrain correction (GTC) registers the pixel
values of the SAR slant range image due to terrain offset and
The basic image generation physics of SAR implies less or no
radiometric information in regions affected by layover and shadowing,
respectively. Therefore, the radiometric values (digital counts) in
extreme layover areas are more or less meaningless. Shadowed regions
will be precisely mapped but stay shadowed in a geocoded image.
To indicate, where the regions of layover and shadow can be found in
the geocoded image, the user of a terrain corrected geocoded image can
get an additional data set in the same carthographic presentation,
showing the pixels affected by those radiometric distortions. The
binary pixel values represent a degree of terrain slope vs. the
regional incidence angle of the SAR. Shadow and layover conditions are
indicated by different bits. The amount of data will be as large as for
the geocoded image to which it belongs. The GIM product can be
generated for GTC and GMQ product sizes.
Aid for the SAR Geocoded Product user for thematic interpretation of
the image content. In digital form, this data may be used as an
additional image layer to generate masks with the image processing
- The standard MGD product formatted in CEOS, including parameters used
for the slant to ground range projection.
- Orbit data from the PATH tape annotated in the MGD product
- Map projection constants to be applied
- Digital Elevation Model
The incidence angle, layover and shadow mask is a by-product during terrain
corrected geocoded product generation. During the application of the
radargrammetric references the sensor is considered as a geometric
scanner with reference to its zero-Doppler position and timing.
By using the geometric relationships, the nominal incidence angle on
undulating ground can now be calculated.
For detection of layover and shadow, two passes in range are necessary.
Input data product GTC, GMQ
Digital Elevation Model
Geometric representation Cartographic, UTM,
ellipsoid used WGS84
Data representation Bit 0 = layover
Bit 1 = shadow
Bit 2-7 = incidence angle
Pixel quantization 8 bit
Spatial Resolution dependent of DEM planar and height resolution
northing 12,5 m
easting 12,5 m
Number of pixels
x-axis 800 . . . 8960
y-axis 800 . . . 8960
Amount of data up to 80 MBytes
Access to the data:
On-line access to data and information as well to digital quicklook DQL
or browse data is provided by the Intelligent Satellite Data Information
System (ISIS), developed by DLR as a client / server configuration.
It represents the interface of DLR-DFD to users, providing easy access to
catalogue-, inventory-, browse- and general textual information.
ISIS can be accessed with World Wide Web by URL:
and clicking on `Information Services (ISIS)` or `Accessing ISIS` (telnet).
ISIS can also be accessed by telnet directly:
input: telnet isis.dfd.dlr.de
Other procedures (modem or X-25) to access ISIS are described as 'Supplemen-
tary Information' for data centers (keyword 'ISIS'. Access presumes the in-
stallation of the client software (available free of charge) which can be
easily done by users (supplied by DLR/DFD).
Digital and photographic products may be ordered at DFD - Help Desk,see Data
There is also available on CD-ROM and on Web a set of image sample products
as well as general and specific information about the X-SAR missions. This
'user-kit' can be accessed via Web with URL:
(Click for Interactive Map)
Start Date: 1994-04-09Stop Date: 1994-10-11
Access Constraints The data is available for download from a Related URL.
Use Constraints This data set conforms to the PICCCBY Attribution License (http://creativecommons.org/licenses/by/3.0/).
Please follow instructions listed in the citation reference provided at http://data.aad.gov.au/aadc/metadata/citation.cfm?entry_id=ASAC_121... when using these data.
Data Set Progress
Distribution Media: HTTP
Distribution Format: shapefile
Role: DIF AUTHOR
Phone: +61 3 6232 3519
Fax: +61 3 6232 3351
Email: metadata at aad.gov.au
Australian Antarctic Division 203 Channel Highway
Province or State: Tasmania
Postal Code: 7050
Role: TECHNICAL CONTACT
Email: eric.woehler at gmail.com
Province or State: Tasmania
Postal Code: 7001
Creation and Review Dates
DIF Creation Date: 2003-07-03
Last DIF Revision Date: 2012-07-23