SDTS DEMs
The Spatial Data Transfer Standard (SDTS) is a file format the USGS uses for distributing geospatial data. The file format is complicated and generally handled well only by advanced software.
About DEMs
A DEM is a digital elevation model. It can be used in ArcView's Spatial Analyst, Model Builder, and 3-D Analyst extensions. To read up more about DEMs, go to the USGS National Spatial Data Clearinghouse DEM web site.
DEMs from each source display characteristic error artifacts
e.g. effects of mis-tagged contours in the products of scanned contour lines
Uses of DEMs ...
DEMs from Imagery
I was wondering if you could steer me to information on how to create
DEMs from imagery. Are there any software products out there, for a
relatively low cost, that can perform that kind of conversion? (I'm ...
The DEMs are being distributed as compressed images, 16-bit binary raster image files in a latitude/longitude coordinate system. The elevation values are given in meters above mean sea level with ocean areas masked as -9999 (representing no data).
Free DEMs are also available for Mars: the MEGDR, or Mission Experiment Gridded Data Record, from the Mars Global Surveyor's Mars Orbiter Laser Altimeter (MOLA) instrument; and NASA's Mars Digital Terrain Model (DTM).[4]
[edit] United States ...
2. 3D DEMs can now be exported to VRML format in addition to DXF and XYZ formats ...
Using USGS DEMs in ArcView GIS - This brief tutorial walks you through the process of importing USGS SDTS format DEMS in ArcView GIS with the help of the SDTS2DEM translator (Nov. 2001) ...
Digital Elevation Models (DEMs) and Viewing Modes
In recent years, contour values have been digitized allowing them to be manipulated into versatile displays of topographic data as digital elevation models or DEMs.
terraflow but provides more accurate results in areas of low slope as well as DEMs constructed with techniques that mistake canopy tops as the ground elevation. Kinner et al. (2005), for example, used SRTM and IFSAR DEMs to compare r.
Various topographic functions can be computed from elevation information provided by DEMs or DTMs. Topographic functions usually are computed from raster data of elevation.
Digital Elevation Models (DEMs) are a type of raster GIS layer. Raster GIS represents the world as a regular arrangement of locations. In a DEM, each cell has a value corresponding to its elevation.
DIGITAL ELEVATION MODELS (DEMs)
A DEM is an image that contains topographic information. These are available for free download (at a low 1 km resolution), or at higher resolutions for a cost.
The late Sol Katz wrote translators to convert SDTS DEMs into the USGS DEM format and ArcInfo grid format (the format used by Spatial Analyst). These translators, sdts2dem.exe and sdts2arc.exe, respectively, are available at many web sites.
LIDAR can also provide archaeologists with the ability to create high-resolution digital elevation models (DEMs) of archaeological sites that can reveal micro-topography that are otherwise hidden by vegetation.
Resolution, in the context of a TIN, is a simpler concept than for DEMs formed from a regular matrix of values.
Digital elevation models (DEMs), orthomosaics and 3D animations are replacing traditional techniques for the display of geospatial information and geographical phenomena.
In a GIS, collections of geographic features are organized into data sets, such as land parcels, fire locations, buildings, orthophoto imagery, and raster-based digital elevation models (DEMs).
The representation of continuous elevation values over a topographic surface by a regular array of z-values, referenced to a common datum. DEMs are typically used to represent terrain relief.
Arc second - A unit of angular measurement that is used to denote the spacing of adjacent profiles in USGS DEMs. An arc second is approximately equivalent to 30 meters of linear measurement.
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The first is 30-meter elevation data from 1:24,000 seven-and-a-half minute quadrangle map. The second is the 1:250,000 3 arc-second digital terrain data. DEMs are produced by the National Mapping Division of USGS.
This means that additional value-added processing can deliver much higher spatially resolved DEMs that can be used for agriculture field leveling/terracing, ...
This data can be arrayed spatially as random points, as a regular grid, or as centroids of polygons. Examples are temperature measured at monitoring stations, digital elevation models (DEMs), and cancer rates per county.
 See also: Information, GIS, Mapping, Resolution, Feature
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