ASTER GDEM

ASTER GDEM
Name	ASTER GDEM
Type	Digital elevation model
Owner	Ministry of Economy, Trade and Industry (Japan), National Aeronautics and Space Administration
Producer	Japan Space Systems, METI, NASA
Released	2009
Latest release	2011 (Version 2)
Format	raster
Resolution	30-meter
Coverage	global

ASTER GDEM

ASTER GDEM is a global digital elevation model derived from stereo pairs of ASTER imagery collected by the Terra satellite, a mission managed by NASA and the Japan Aerospace Exploration Agency. The dataset was produced through collaboration among METI, NASA, Japan Space Systems, and an international community of researchers, and it quickly became a widely used elevation product alongside datasets from Shuttle Radar Topography Mission, SRTM, and national mapping agencies. ASTER GDEM supports applications across earth science, environmental monitoring, urban planning, and disaster response involving organizations such as United Nations agencies and regional research institutes.

Overview

ASTER GDEM provides near-global topographic coverage generated from optical stereo data captured by the ASTER instrument aboard Terra. The project involved automated stereoscopic processing by METI and NASA using algorithms developed in collaboration with institutions like University of Tokyo, University of Maryland, and corporate partners including Hitachi and Fujitsu. Released initially in 2009, the model complements other elevation data such as SRTM, Lidar surveys by national agencies like USGS, and commercial products from companies like Airbus and Maxar Technologies.

Data and Coverage

ASTER GDEM covers most of Earth's land surfaces between 83°N and 83°S using stereo-pair scenes from ASTER, yielding a nominal horizontal resolution of 30 meters. The dataset aggregates millions of ASTER scenes acquired over years of operations of Terra, including repeat observations over regions such as the Himalayas, Andes, Rocky Mountains, Alps, Sahara, Amazon Basin, and Antarctica. Coverage gaps exist over persistent cloud cover areas and regions with limited stereo pairs, affecting islands like Greenland and archipelagos such as the Aleutian Islands. Input imagery originates from an instrument developed by JAXA partners and processed with software influenced by academic groups including Caltech and Massachusetts Institute of Technology.

Processing and Accuracy

ASTER GDEM was produced using automated image matching, stereo correlation, and post-processing filters to remove outliers, with quality control steps informed by work at Jet Propulsion Laboratory and research centers like National Institute of Advanced Industrial Science and Technology. Accuracy varies by terrain, with vertical errors reported relative to benchmarks from International GNSS Service stations, national geodetic networks such as National Geodetic Survey, and airborne lidar datasets operated by NOAA and USGS. In flat low-relief areas the vertical error can be within a few meters, whereas in high-relief alpine zones like the Karakoram and Andes errors can exceed tens of meters. Comparisons with SRTM and lidar have been performed by groups at University of Zurich, University of Colorado, and ETH Zurich highlighting systematic artifacts such as striping and voids in steep terrain.

Versions and Revisions

The initial public release occurred in 2009, followed by a major revision, Version 2, in 2011 that incorporated additional ASTER scenes and improved processing routines. Subsequent internal updates adjusted calibration parameters used by teams at METI and NASA and drew upon validation work from institutions like Australian National University, King Abdullah University of Science and Technology, and University of California, Santa Barbara. Versioning addressed known anomalies identified by independent evaluators including researchers from University of Tokyo and agencies such as European Space Agency that compared ASTER GDEM to Copernicus products and other global DEM initiatives.

Applications

ASTER GDEM has been applied in studies of glacier change in the Himalayas and Alps, hydrological modeling for watersheds including the Mississippi River and Amazon River, and hazard mapping for volcanic regions like Mount Etna and Mount Fuji. Urban planners in cities such as Tokyo, Los Angeles, and London have used ASTER-derived elevation data for flood risk assessments and infrastructure planning, while conservation groups and researchers at WWF and IUCN employed it for habitat mapping in regions like the Congo Basin and Madagascar. Disaster response agencies, including branches of the United Nations Office for the Coordination of Humanitarian Affairs and national civil protection agencies, have used ASTER GDEM in conjunction with satellite imagery from Landsat and Sentinel-2 for rapid terrain assessment.

Limitations and Criticisms

Critics highlighted artifacts such as noise, pits, and false depressions in Version 1, leading to caution in high-precision applications compared with airborne lidar from providers like Quantum Spatial and national surveys such as Ordnance Survey. Studies by teams at University of Washington, University of Leeds, and Chinese Academy of Sciences reported limitations in vegetated, glaciated, and snow-covered regions where stereo matching fails. The modest vertical accuracy relative to lidar and high-resolution commercial DEMs limits use in cadastral mapping, engineering surveying, and construction projects overseen by institutions such as Royal Institution of Chartered Surveyors and national cadastral agencies. Metadata and provenance concerns prompted calls for more rigorous validation workflows similar to practices at USGS and ESA for flagship datasets.

Access and Distribution

ASTER GDEM is distributed publicly at no cost via platforms managed by METI and NASA, with mirror hosting and discoverability improved through portals like Earthdata and university data repositories hosted by institutions such as University of California, Berkeley, PANGAEA, and NASA Earth Observing System Data and Information System. Data formats follow common geospatial raster conventions compatible with software from Esri, QGIS, GDAL toolkits, and scientific computing environments at NASA research centers and academic labs. Users seeking higher-precision alternatives can reference national lidar archives maintained by USGS and commercial offerings from Airbus and Maxar Technologies.

Category:Digital elevation models