A proposal for a global database with DEM-derivatives.

1. An open database of DEM-derivatives of the World
T. Hengl & H.I. Reuter
Global DEM-derivatives Proposed implementation
The idea of a global repository of DEM-derivatives is not new. USGS has The database needs to guarantee the following five criteria (Hengl & Reuter
been maintaining the global 1 km HYDRO1k (http://eros.usgs.gov) --- a 2008):
repository of DEM derivatives (elevation, WTI, slope, aspect, flow direction,
flow accumulation, drainage basins and streams). San Diego Supercomputer Precision --- It needs to provide the best estimates of surface measures and
Center hosts a project called "Open Topography" objects, derived from the most accurate and current data and al-
(http://opentopography.org/) that aims at serving high resolution (LiDAR) gorithms.
data and tools. Esri™ will build and host a collection of multiresolution DEM
Multiscale --- Input DEM need to reside within a multi-scale GIS so that it can
derivatives, starting with SRTM and analytic services against it, as well as
be available at various resolutions.
higher resolution DEM derivatives for places where the data is freely
available. The data will all be available for free on ArcGIS.com. Open structure --- Users should be able to modify and adjust spatial queries
to tailor surface measures and objects to fit specific needs.
Web access --- The system should provide a high performance cached map
services and interactive analytic functions as web services (e.g.
viewshed and watershed delineation).
Quality --- the input (DEMs) and algorithms should be continually evaluated
and improved and maintained to ensure their fitness for use (minimum
artifacts).
Spatial query GEOMORPHOMETRIC ATLAS
Thematic properties
DEM
- LSP/LSOs type
- algorithms
- pre-processing steps
Function
library
Spatial properties
- coordinate system
- spatial resolution *Activate functions
LSPs / matching the best
- extent (boundaries)
Fig. 1: An example of a complete topographic model of the world at resolution of 1 km. For more info LSOs with users’ request
according to the
see: http://commons.wikimedia.org/wiki/File:Globedem.png organizer criteria
WEB-INTERFACE
On the other hand, it is difficult for a
single investigator or even one group to
undertake complex geomorphometry on a New data
Outputs
global scale --- instead, cooperative type date
initiatives (such as the
geomorphometry.org) are needed.
Fig. 3: Conceptual design for a geomorphometric atlas: a user defines
An open database of DEM- various parameters and then downloads the data. Processing and
derivation of surface descriptors is done directly on the server.
derivatives LSP/LSO = Land Surface Parameters/Objects.
We propose here initiation of open Conclusions
database of DEM derivatives (a geo-
morphometric atlas) --- an international Demand for DEMs and their derivatives, evident from many different
network of mirrored servers that will host disciplines and applications, will prompt ever higher expectations for rigor
the largest collection of DEM derived and force the global scientific community to commit to an ongoing review of
products including reference methods, data standards. The Global DEM-derivatives initiative is a platform for
software tools and standards. meeting these expectations.
Fig. 2: The landform classification following
Such geo-database would support the Iwahashi and Pike (2007). Relief classes References:
which are classified using an unsupervised
development of knowledge libraries, as nested-means algorithms.
Hengl, T., Reuter, H.I. (eds) 2008. Geomorphometry: Concepts, Software, Applications. Developments in Soil Science,
vol. 33, Elsevier, 772 pp.
well as continued testing and comparison Kleiner, K., 2011. Data on demand. Nature Climate Change 1, 10–12.
of geomorphometric methods by the scientific community (Kleiner, 2011). Iwahashi, J. and R. J. Pike, 2007. "Automated classifications of topography from DEMs by an unsupervised nested-
means algorithm and a three-part geometric signature." Geomorphology 86(3-4): 409-440.
ISRIC - World Soil Information, Wageningen University
PO Box 353, 6700 AJ Wageningen, the Netherlands
URL: http://www.isric.org
E-mail: {tom.hengl; hannes.reuter}@wur.nl