Introducing the Global Elevation Data Testing Facility

SUMMARY One of the major stages in the production of a digital elevation model (DEM) is the development of its accuracy statement. This is typically done by summarising errors contributed at all stages of the DEM production and/or comparison of the assessed DEM with a reference elevation dataset. Obviously, a DEM accuracy statement is less accurate in areas where reference data are not available or are of poor quality, and/or the DEM production technique involves many stages with various types of errors. The Jet Propulsion Laboratory team faced such a situation while working on the production of a near-global DEM from the interferometry data acquired during the shuttle radar topography mission (SRTM) in February 2000. To tackle these obstacles, the task of producing the accuracy statement for the SRTM proved to be extremely time-consuming and very expensive. One of the reasons for this situation was the lack of a test bed for elevation measurements which would be of the highest quality and accuracy and available globally. In the near future, at least two additional global DEMs—the ASTER DEM and the TanDEM- X—will be available. Some more, perhaps with regional extent, will be produced in the next decade or so. The authors of these DEM will doubtlessly face a similar task to independently verify the accuracy of their products. In consideration of the difficulties presented above, the global elevation data testing facility (GEDTF) was introduced. The facility will develop and maintain a database of areas of our planet which fulfil certain conditions suitable for the elevation testing purposes. These requirements include: a) flat and homogeneous surface and b) known slope, aspect and elevation of the surface. Among the best candidates fulfilling these requirements are runways of airports, but any other type of natural or man-made areas could also be considered. In this paper we present a detailed vision, framework, basic requirements and conditions of GEDTF. The paper also details the technological stages in the development of GEDTF that are currently being performed. The first version of the facility should be available online in a few months. The development and maintenance of GEDTF is funded by the government of Brunei Darussalam via its Science and Research programme.