Environmental Engineering Reference
In-Depth Information
possibly dynamic 3D objects. These data types have very different characteristics and
requirements in terms of management, visualisation and multi-scale representation.
Digital Terrain Elevation Data (Raster)
At present, available through many databases, the GTOPO30 elevation data (around
1:1,000,000 scale) (
http://edc.usgs.gov/products/elevation/gtopo30/gtopo30.html
)
are not accurate enough. For testing, we have used the NASA Shuttle Radar
Topographic Mission (SRTM) data. This data is currently distributed free of charge
by USGS and is available for download from the National Map Seamless Data
Distribution System, or the USGS ftp site (
http://glcfapp.umiacs.umd.edu:8080/
esdi/index.jsp
)
. The SRTM data is available as three arc second (~90 m resolution)
DEM. A one arc second data product was also produced, but is not available for all
countries. The vertical error of the DEM is reported to be less than 16 m. We need
at least these kinds of scale datasets but more accurate data like the IGN® BD
ALTI® (50 m resolution,
https://professionnels.ign.fr/ficheProduitCMS.
do?idDoc = 5323461
) gives better results.
Land Cover Classification Data (Raster or Vector)
For vegetation placement, we can use self-made scientist datasets and/or CORINE
Land Cover like datasets (
http://dataservice.eea.europa.eu/dataservice/metadetails.
asp?id = 822
). Land use and land cover maps show areas of land as 'parcels' or
polygons. Each parcel has attached to it a list of values or attributes, covering such
topics as land cover class, parcel area, length of boundary, processing history, knowledge-
based correction and identification of the original satellite scene. We need these kinds
of data to display actual and simulated landscape, i.e. the environmental impacts of a
simulated scenario in SEAMLESS need to be translated into land cover data.
Geotypical Textures Library (Raster)
For texture splatting (a method for combining different textures) on the terrain, we need
a collection of textures for the different land cover classes we could find (e.g. wheat,
corn and grassland). A preliminary library of textures is being developed, and if necessary,
according to the user requirements, a variety of different textures can be added.
Orthophoto (Raster)
For rendering more realistic landscape, an orthophoto (an aerial photograph that
has been geometrically corrected such that the scale of the photograph is uniform)
can be draped over the terrain and blended with the geotypical soil textures.
