MODIS remote sensing at MPBA group/IRST

ASTER DEMs

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) is a 14-channel visible to thermal-infrared sensor that was launched as part of the Earth Observing System (EOS) Terra payload on 18 December 1999. ASTER is an on-demand instrument.

The ASTER data set contains topographic information derived from the along-track, 15 m ASTER optical stereo data acquired in near-infrared bands 3N and 3B. These high spatial resolution DEMs (up to 7 m absolute horizontal and vertical accuracy with appropriate ground control, and up to 10 m relative accuracy without ground control) can be used to derive absolute slope and slope aspect good to 5 degrees over horizontal distances of more than 100 m. ASTER DEMs should meet 1:50,000 to 1:250,000 map accuracy standards ([1]:112). An autocorrelation approach using proprietary software at the LP-DAAC produces DEMs from Level-1A or 1B digital stereo pairs. Both absolute DEMs as well as relative DEMs are produced. For an absolute DEM Ground Control Points (GCPs) must be provided for the area of interest. A relative DEM is generated by using only the satellite ephemeris data and is horizontally not nearly as accurate as the absolute DEM.

In summary, two types of ASTER-DEM are available:

absolute DEM: the user has to provide ground control points
relative DEM: geopositioning of the DEM is calculated from the satellite ephemeris data (less precise).

To find out the type of ASTER-DEM, gdalinfo may be used:

gdalinfo ASTER_DEM20020827134235.hdf | grep DEMType
  DEMType=Relative

GRASS can directly import ASTER-DEM (import into a UTM/WGS84 location).

References

[1] Jet Propulsion Laboratories, ASTER Higher-Level Product User Guide, JPL D-20062, May 2001, PDF

ASTER DEMs

ASTER DEMs

References

See also