- CALIFORNIA DIGITAL TERRAIN MODEL HOW TO
- CALIFORNIA DIGITAL TERRAIN MODEL MANUAL
- CALIFORNIA DIGITAL TERRAIN MODEL FULL
- CALIFORNIA DIGITAL TERRAIN MODEL SERIES
GTOPO30 was derived from several raster and vector sources of topographic information. Global Bathymetry and Elevation Digital Elevation Model: SRTM30PLUS v8 (30 arc. Geological Survey (USGS) with a horizontal grid spacing of 30 arc seconds (approximately 900 meters). GTOPO30 is a global Digital Elevation Model (DEM) produced by the U.S. This data was collected during the Shuttle Radar Topography Mission (SRTM) and contains global coverage from 56 degrees south latitude to 60 degrees north latitude withĪn approximate resolution of 900 by 900 meters. This data was collected during the Shuttle Radar Topography Mission (SRTM) and contains global coverage from 56 degrees south latitude to 60 degrees north latitude in 1īy 1 degree blocks with an approximate resolution of 90 by 90 meters.
CALIFORNIA DIGITAL TERRAIN MODEL FULL
This data was collected during the Shuttle Radar Topography Mission (SRTM) and contains full coverage of the United States in 1 by 1 degree blocks with an approximate Meter resolution for all of the contiguous United States, Hawaii, and limited portions of Alaska. Geological Survey (USGS) and provide coverage in 1 by 1 degree blocks with approximately 90 by 90 These Digital Elevation Model (DEM) data files are produced by the U.S. On 30 by 30 meter data spacing with the Universal Transverse Mercator UTM projection. Geological Survey (USGS) as part of the National Mapping Program. All nonstandard quadrangles with neat-lines that extend beyond the standard unit size to accommodate overedge boundaries are collected and sold as multiples of the standard unit sizes.WebGIS - Free Terrain Data - Geographic Information Systems Resource - GIS In Alaska these are west, central, and east files. (All values are latitude-longitude, respectively.) DEM data are produced by the National Imagery and Mapping Agency (NIMA) in lby 1-degree units that correspond to the east or west half of USGS 1by 2-degree topographic quadrangle map series(1:250,000 scale) for all of the United States and its territories.
cover 15by 30-minute areas, and those north of 68ù N. cover 15by 22.5-minute areas, those between 62ùand 68ù N. cover 15by 20-minute areas, those between 59ù and 62ù N. The unit sizes in Alaska vary depending on the latitude.
CALIFORNIA DIGITAL TERRAIN MODEL SERIES
DEM data for 15-minute units correspond to the USGS 15-minute topographic quadrangle map series in Alaska. This series is distributed as four units of 15-minute DEM data covering full 30by 30-minuteareas that correspond to the east or west half of the USGS 30by 60-minute topographic quadrangle map series (1:100,000 scale). Data for 2-arc-second (30 minute) DEM's provide coverage for the conterminous United States, except Alaska. Unit Size and File Extent DEM data for 7.5-minute units correspond to the USGS 7.5-minute topographic quadrangle map series for all of the United States. DEM data for 1-degree units are collected from topographic map sources, ranging from the 7.5-minute map series to the 1by 2-degree map series, or from photographic sources by using image correlation systems.
CALIFORNIA DIGITAL TERRAIN MODEL HOW TO
DEM data for 15-minute and 2-arc-second (30 minute) units are derived from DLG hypsographic and hydrographic data. Astrogeology team member, David Mayer, presented a poster at the Lunar and Planetary Science Conference in The Woodlands, Texas on how to produce DTMs of Mars using the free Ames Stereo Pipeline software.
CALIFORNIA DIGITAL TERRAIN MODEL MANUAL
The following three methods (now discontinued or deactivated) were used primarily for the production of 7.5-minute DEM data: (1) the Gestalt Photo Mapper II (2) manual profiling from photogrammetric stereomodels (3) interpolation of the elevations from stereomodel digitized contours. Of these methods, only one, interpolation from vectors or digital line graph (DLG) hypsographic and hydrographic data, is currently used for7.5-minute DEM's and other series DEM's. The USGS has used four methods to collect DEM data.
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