Digital Elevation Models (DEMs) Mapping Our World in 3D

There is a variety of DEM - http://www.satimagingcorp.com/gallery-dem.html - source data available for developed areas and the suitability of this available data is depending on the project specifications. In remote regions around the World, were little or no source Data is available, the DEM can be produced by automatic DEM extraction from stereo satellite scenes, from Satellite sensors such as IKONOS (2-5m resolution), SPOT-5 (5-10m res.) and ASTER (15-25m res.). The DEM can also be provided from Stereo Digital Aerial Photography at various resolutions, depending on the quality and scale of the Aerial Photography.

To represent the earth's surfaces and bathymetry/hydrographic features in a 2D or 3D Geographic Information Systems (GIS) or CAD computer environment relative to existing geodetic horizontal and vertical datum's the reference surfaces have to be clearly defined.

Orthorectified Satellite Images and Aerial Photography which can be processed for visualization of terrain conditions in 3 Dimensions (3D) or Digital Elevation Model (DEM) which are generated from a variety of resources. In addition to the Orthorectification of Remote Sensed Images, the DEM's are utilized in support of the pre-planning and lay-out of corridor surveys, area developments, seismic line locations, Well sites and Engineering, Construction activities, Environmental and Geological purposes.

The term Digital Elevation Model (DEM) has several meanings and is not always understood correctly or misinterpreted due to the surface it represents or geographic location the DEM data is being used. As used in most of the western hemisphere a DEM has "Bare Earth" z-values at regularly spaced intervals in x (Easting's) and y (Northing's). In some countries the x and y orientation are opposite from the general use with "x" being Northing and "y" Easting. Because of many different horizontal and vertical geodetic reference systems available around the world the necessity to clearly define the 3D geodetic reference system to be utilized is critical to a projects success to obtain the mapping standards defined.

Category:

Science & Technology

Tags:

• worldview 1
• quickbird
• ikonos
• geoeye-1
• landsat
• aster
• spot-5
• satellite photos
• satellite imaging
• satellite images
• satellite image
• 3d terrain visualization
• aerial photography
• digital elevation models
• dem
• land cover
• change detection
• agriculture
• forestry
• cadastre
• pipeline corridor
• earth observation
• earth photos
• remote sensing