For knowing more on DEM/DTM check the link digital elevation modeling
georectification services
Showing posts with label digital elevation model. Show all posts
Showing posts with label digital elevation model. Show all posts
Tuesday, March 2, 2010
Tuesday, February 16, 2010
Creation ofDigital Elevation Model (DEM)
For the accurate removal of the image distortions, a digital elevation model (DEM) is used to make image orthorectification. The requisite DEM can be produced by semi-automatic DEM extraction software from stereo satellite scenes obtained by the QuickBird, IKONOS, SPOT-5, or ASTER satellite sensors, and stereo aerial photography.
In situations where higher mapping accuracy standards are required, the DEM is extracted from the already existing topographic maps with reference to a standard scale or collected using stereo satellite image data.
To obtain this accuracy standard, adequate GPS-derived ground control points (GCPs) are necessary. Other remote sensing techniques can also be used such as radar interferometry or LIDAR.
When a particular vector data needs to be extracted from satellite or aerial image data by raster-to-vector translation, the process of ortho rectification of the remotely sensed image data can rectify all digital images of geological, environmental, topographic or any other source map which will be used in the GIS mapping environment.
In situations where higher mapping accuracy standards are required, the DEM is extracted from the already existing topographic maps with reference to a standard scale or collected using stereo satellite image data.
To obtain this accuracy standard, adequate GPS-derived ground control points (GCPs) are necessary. Other remote sensing techniques can also be used such as radar interferometry or LIDAR.
When a particular vector data needs to be extracted from satellite or aerial image data by raster-to-vector translation, the process of ortho rectification of the remotely sensed image data can rectify all digital images of geological, environmental, topographic or any other source map which will be used in the GIS mapping environment.
Thursday, January 14, 2010
Digital Elevation/ Digital Terrain Model Tips (DEM/DTM)
Digital elevation are frequently obtained by remote sensing rather than direct survey. These can be prepared in a number of ways,but one of the powerful technique for generating digital elevation model is interferometric synthetic aperture radar: two passes of a radar satellite (such as RADARSAT-1), or a single pass if the satellite is equipped with two antennas (like the SRTM instrumentation), suffice to generate a digital elevation map tens of kilometers on a side with a resolution of around ten meters.
A digital elevation model (DEM) or digital elevation modeling is a digital representation of ground surface topography or terrain, thus also widely known as a digital terrain model (DTM) or digital terrain modeling. A DEM can be represented as a raster , a grid of squares or as a triangular irregular network. digital elevation models are commonly built using remote sensing techniques, but they may also be built from land surveying. DEMs are used often in GIS, and are the most common basis for digitally-produced relief maps. DTM DEM generation is commonly used in remote sensing gis.
A digital elevation model (DEM) or digital elevation modeling is a digital representation of ground surface topography or terrain, thus also widely known as a digital terrain model (DTM) or digital terrain modeling. A DEM can be represented as a raster , a grid of squares or as a triangular irregular network. digital elevation models are commonly built using remote sensing techniques, but they may also be built from land surveying. DEMs are used often in GIS, and are the most common basis for digitally-produced relief maps. DTM DEM generation is commonly used in remote sensing gis.
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