EDG Data Set Name ASTER On-Demand L3 Orthorectified Images
Granule Shortname AST14OTH
Data Set Characteristics
Area: ~60 km x 60 km (ASTER Level-1A input image)
Input and Output Image Resolution: 15, 30, 90 meters
File Size: ~132 MB
Image Dimensions: Varies by scene
Map Projection: Universal Transverse Mercator (UTM)
Resampling Method: Cubic Convolution
Data Format: GeoTIFF
This is an Orthorectified ASTER Level-1B image of the northwestern part of Los Angeles County with a backdrop of the Tehachapi mountains. In the lower right is the northwestern end of the San Fernando Valley with Santa Clarita to its north. In the middle right is Castaic Lake with Interstate-5 trending northwest to southeast. Healthy vegetation appears in red in contrast to a couple of burn scars, one in the middle left (north of Simi Valley), while the other one in the north in the Angeles National Forest.
Product Description
The ASTER On-Demand Orthorectified Image products contain imagery transformed from a perspective projection to an orthogonal one. An orthorectified image possesses the geometric characteristics of a map, with near-vertical views for every location. These products are terrain-corrected, provide radiometrically calibrated radiance, and are mapped to the Universal Transverse Mercator coordinate system. The inputs include the following: an ASTER Level-1A Reconstructed Unprocessed Instrument data set; georeferencing information from the ASTER instrument's and Terra platform's ephemeris and attitude data; and an ASTER-derived digital elevation model (DEM). The output product includes fifteen orthorectified ASTER Level-1B calibrated radiance images, one per band, as listed below.
Product Output Information
Spectral Range (µm)
Units
Data Type
Valid Range
Unit Conversion Coefficient*
VNIR (15 Meters)
Normal Gain
Band 1 (0.52 - 0.60)
w/m2/sr/µm
8-bit unsigned integer
0 - 255
1.688
Band 2 (0.63 - 0.69)
w/m2/sr/µm
8-bit unsigned integer
0 - 255
1.415
Band 3N (0.78 - 0.86)
w/m2/sr/µm
8-bit unsigned integer
0 - 255
0.862
Band 3B (0.78 - 0.86)
w/m2/sr/µm
8-bit unsigned integer
0 - 255
0.862
SWIR (30 Meters)
Band 4 (1.600 - 1.700)
w/m2/sr/µm
8-bit unsigned integer
0 - 255
0.2174
Band 5 (2.145 - 2.185)
w/m2/sr/µm
8-bit unsigned integer
0 - 255
0.0696
Band 6 (2.185 - 2.225)
w/m2/sr/µm
8-bit unsigned integer
0 - 255
0.0625
Band 7 (2.235 - 2.285)
w/m2/sr/µm
8-bit unsigned integer
0 - 255
0.0597
Band 8 (2.295 - 2.365)
w/m2/sr/µm
8-bit unsigned integer
0 - 255
0.0417
Band 9 (2.360 - 2.430)
w/m2/sr/µm
8-bit unsigned integer
0 - 255
0.0318
TIR (90 Meters)
Band 10 (8.125 - 8.475)
w/m2/sr/µm
16-bit unsigned integer
0 - 65535
6.882 x 10-3
Band 11 (8.475 - 8.825))
w/m2/sr/µm
16-bit unsigned integer
0 - 65535
6.780 x 10-3
Band 12 (8.925 - 9.275)
w/m2/sr/µm
16-bit unsigned integer
0 - 65535
6.590 x 10-3
Band 13 (10.25 - 10.95)
w/m2/sr/µm
16-bit unsigned integer
0 - 65535
5.693 x 10-3
Band 14 (10.95 - 11.65)
w/m2/sr/µm
16-bit unsigned integer
0 - 65535
5.225 x 10-3
*Unit Conversion Coefficient (UCC) values are provided for each channel in the encapsulated ASTER Level-1 metadata under the UNITCONVERSIONCOEFFICIENT Group, and within the INCL Object of the Product Metadata for each sensor. UCCs provide the slope or inclination values in units of watts/meter2/steradian/micrometer per DN.
Differences between an ASTER Level-1B data set and ASTER Orthorectified Images
ASTER Level-1B data consist of calibrated radiance in a path-oriented UTM projection, whereas ASTER orthorectified images are presented in a north-up UTM projection. ASTER orthorectified images possess the geometric characteristics of a map with near-vertical views for every location, and they also are terrain-corrected.
ASTER L1B image dimensions for each of the three sensor systems (VNIR, SWIR, and TIR) are different because of their different spatial resolutions; those image dimensions remain constant from one L1B scene to another. However, ASTER orthorectified image dimensions can vary from scene to scene. This is because the image dimensions of the ASTER Digital Elevation Model (DEM) used in the orthorectification process can vary, and the DEM’s image dimensions define the output dimensions for each of the three sensor’s orthorectified images.
The ASTER Level-1B data set is provided in a single multi-file packaged Hierarchical Data Format (HDF) with specific EOS conventions. The ASTER orthorectified image file format is GeoTIFF. The file includes fifteen orthorectified ASTER Level-1B calibrated radiance images, one for each band. These image files are compressed and provided to the user in a single zip file.
Ordering ASTER On-Demand L3 Orthorectified Images
The ASTER On-Demand L3 Orthorectified product is produced by first selecting an ASTER Level-1A input data set through the EOS Data Gateway. In addition, an ASTER DEM is used as an input to the process of generating the orthorectified products. The ordering process and procedures are described in the following tutorial: http://lpdaac.usgs.gov/tutorial/.
LP DAAC User Services
U.S. Geological Survey (USGS)
Earth Resources Observation and Science Center (EROS)
47914 252nd Street
Sioux Falls, SD 57198-0001