ASTER LEVEL 1 DATA
Naming convention
|
|
ASTER LEVEL 1 DATA |
|
The ASTER Level-1 File naming convention (from GDS) breaks down as follows:
pg-PR1B0000-2001021503_007_001
PR1B0000: Processing level
2001: Production date (year)
02: Production date (month)
15: Production date (day)
03: Sequence number of production plan for that particular day
<007: Processing strip number
001: Sequence number in the processing strip
The ASTER Level-1 file is distributed without a .hdf suffix. It is a good idea to rename files with it:
pg-PR1B0000-2001021503_007_001.hdf
This will enable image processing software to identify this particular format.
Interpreting ASTER Level-1 file names and granule/scene IDs
An ASTER Level-1 granule-ID on the EDG is specified:
SC:AST_L1A.002:2004799662
Following an order, an ASTER Level-1 granule is distributed with a file name like:
pg-PR1A0000-2001111802_042_013
(file naming convention from GDS)
along with an ECS-generated metadata file:
pg-PR1A0000-2001111802_042_013.met
The information used to match the file to the granule/scene ID is the date and time found in the EDG-returned results and the embedded metadata file.
The embedded file exists as part of the header within the image file. Some of the commercial and public domain software allow you to open this information and save it as an ASCII file. For more detail information about HDF metadata contact MadMappers.
The date and time on the EDG-returned results for scene
SC:AST_L1A.002:2004799662
is 05 Nov 2001, 10:37:24, which is the acquisition date and time.
However, the values in the distributed file name
(pg-PR1A0000-2001111802_042_013)
are the date and time that the scene was produced.
To match a file name with an image in archive, the GDS ID found within the productmetadata.0 file (hidden file) under the object attribute IDOFASTERGDSDATAGRANULE can be used.
For example:
ASTL1A 0111051037240111180891
(scene SC:AST_L1A.002:2004799662 file pg-PR1A0000-2001111802_042_013)
can be interpreted:
Format: ‘ASTL1A YYMMDDHHMMSSyymmddNNNN’ where,
YYMMDD: observation date
HHMMSS: observation time
yymmdd: the data granule generation date
NNNN: the data granule sequential No. per day
So ASTL1A 0111051037240111180891 translates to:
011105: observation date
103724: observation time
011118: the data granule generation date
0891: the data granule sequential No. per day
Aster and MadMappers:
The Madmappers Team routinely processes ASTER Level-1A, ASTER Level-1B and Expedited ASTER Level-1 into products for topographic, spectral and digital elevation model studies. Furthermore MadMappers is capable of processing ASTER Level-1A into ASTER Level-1B by applying the appropriate corrections. By virtue of being able of generating Aster DEM products, orthorectification is also achieved. Furthermore MadMappers is able to schedule data acquisitions for selected study areas in Africa.
Aster products are undoubtedly superior to their Landsat 7 equivalent due to their superb clarity and crispiness.
Software:
Until recently only advanced remote sensing software was the
only means to access native Aster data in HDF format. The excellent Globalmapper
can now read and convert HDF data into formats suitable to common GIS software.
MadMappers collection comprises of Aster data suitable for use in OziExplorer.
Additional details regarding the instrument, data products etc. can be accessed from: