Alaska coverage is partially available now and is being expanded to statewide coverage as part of the Alaska Mapping Initiative.
#Digital terrain model graphics full
with full coverage of the 48 conterminous states, Hawaii, and U.S. Horizontal coordinates are referenced to Albers Equal Area Conical projection.ġ/3 arc-second – This is the highest resolution seamless DEM dataset for the U.S. The 1/9 arc-second dataset will no longer be updated with newly acquired DEMs however, it will continue to be distributed.ĥ meter – This dataset is comprised of 5-meter IfSAR-derived DEMs (3DEP quality level 5) over Alaska only. Horizontal coordinates are referenced to geographic coordinates (longitude, latitude). and is produced from 3-meter or higher resolution DEMs acquired by the USGS prior to January 2015. Horizontal coordinates are referenced to the Universal Transverse Mercator projection.ġ/9 arc-second – This dataset covers about 25 percent of the conterminous U.S. These data are distributed in tiles that can be merged to support analysis across large geographic areas.ġ-meter – This dataset was introduced in 2015 with limited coverage of the U.S., but will be expanding as new DEMs from 3DEP quality level 2 or better lidar data are acquired. Seamless DEMs are produced by blending only the highest quality project data into a continuous terrain surface for the U.S. Project-based DEMs are available for the full areal extents of projects when produced from light detection and ranging (lidar), or as one-degree blocks with overedge when produced from IfSAR. Standard DEMs are characterized either as project-based or seamless. Each DEM dataset is identified by its horizontal resolution and is produced to a consistent set of specifications. Standard DEMs represent the topographic surface of the earth and contain flattened water surfaces. The collection is located under the Digital Elevation category.
#Digital terrain model graphics download
EarthExplorer can be used to search, preview, and download IFSAR Alaska data. The pixel values for the grayscale images represent elevation numbers.
![digital terrain model graphics digital terrain model graphics](https://pbs.twimg.com/media/EBc35AHXsAAY2zb.jpg)
This topographic product reflects the height of bare earth where the elevations of vegetation and man-made features have been removed. The USGS Earth Resources Observation and Science (EROS) Center distributes IFSAR Alaska products in Georeferenced Tagged Image File Format (GeoTIFF). IfSAR digital terrain model (DTM): provide elevation values of the underlying terrain of the earth’s surface. This topographic product contains the height of the highest surface on the ground including vegetation, man-made structures, and bare earth. IfSAR digital surface model (DSM): These 5 meter rasters, available only in Alaska, are the initial IfSAR product. DSMs provide elevation values of landscape features on the earth's surface.
![digital terrain model graphics digital terrain model graphics](https://i.ytimg.com/vi/FWloVW5kqtY/maxresdefault.jpg)
Source DEM’s processed by the USGS after January 2015 are provided where the original DEM horizontal resolution or projection differ from the 3DEP standard DEM datasets.ĭifference between a digital surface model (DSM) and digital elevation models (DEM). Source resolution DEMs: these data are the original bare earth DEMs derived from lidar point cloud source. Distinctions in nominal pulse spacing are provided in the lidar point cloud status graphics and in the download platform however, other qualities such as vertical accuracy must be examined to determine if the data meet particular 3DEP quality level specifications. Most of the data collected in 2014 and later meet 3DEP specifications for quality level 2 nominal pulse spacing and vertical accuracy, and data collected prior to 2014 often do not meet the quality level 2 specification. Lidar point cloud: These data are the foundational data for 3DEP in the conterminous U.S., and contain the original three-dimensional information from which the DEM products are derived.