Updated digital elevation model (DEM) dataset files are now given a name that includes information about the resolution and format of the data. This prevents users from accidentally overwriting existing data that might have different resolutions and formats.
For example:
an older file: n44w071.zip
would now have the name: USGS_13_n44w071.tif
indicating 1/3 arc-second elevation data in geotiff format for the 1x1 degree tile.
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What is the difference between lidar data and a digital elevation model (DEM)?
Light detection and ranging (lidar) data are collected from aircraft using sensors that detect the reflections of a pulsed laser beam. The reflections are recorded as millions of individual points, collectively called a “point cloud,” that represent the 3D positions of objects on the surface including buildings, vegetation, and the ground. Digital elevation models (DEMs) are one of many products...
What is a digital elevation model (DEM)?
A Digital Elevation Model (DEM) is a representation of the bare ground (bare earth) topographic surface of the Earth excluding trees, buildings, and any other surface objects. DEMs are created from a variety of sources. USGS DEMs used to be derived primarily from topographic maps. Those are being systematically replaced with DEMs derived from high-resolution lidar and IfSAR (Alaska only) data...
What is the projection, horizontal datum, vertical datum, and resolution for a USGS digital elevation model (DEM)?
Projection: 3DEP DEMS have different projections/coordinate systems depending on the product: 1/3-, 1-, and 2-arc-second (also the discontinued 1/9-arc-second) DEMs are not projected. They are all in geographic coordinates (latitude/longitude). 5-meter DEMs (Alaska only) are Alaska Albers Equal Area. 1-meter DEMs are in Universal Transverse Mercator (UTM). Original Product Resolution (OPR) DEMs –...
How do I report errors in 3D Elevation Program (3DEP) elevation data?
If you think you’ve found an error in USGS elevation data, please send an email to tnm_help@usgs.gov. We will add the reported information to our "Digital Elevation Model Issues" data log for further analysis and possible correction. Spikes, pits, seam-line anomalies, and other data errors are of concern to us. We are working to correct or minimize known issues, but it will take some time. Errors...
What is Lidar data and where can I download it?
Light Detection and Ranging (lidar) is a technology used to create high-resolution models of ground elevation with a vertical accuracy of 10 centimeters (4 inches). Lidar equipment, which includes a laser scanner, a Global Positioning System (GPS), and an Inertial Navigation System (INS), is typically mounted on a small aircraft. The laser scanner transmits brief pulses of light to the ground...
Where can I find 3D Elevation Program (3DEP) product updates and status maps?
3D Elevation Program (3DEP) product updates and status maps are available at these sites: Updates The National Map Data Delivery News Subscribe to Simple Notification Services to receive emails regarding changes to the status of The National Map Services Status Maps The National Map Download Client – Click “Show” below each elevation product LidarExplorer – Lidar point cloud only DEM Availability...
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- FAQ
What is the difference between lidar data and a digital elevation model (DEM)?
Light detection and ranging (lidar) data are collected from aircraft using sensors that detect the reflections of a pulsed laser beam. The reflections are recorded as millions of individual points, collectively called a “point cloud,” that represent the 3D positions of objects on the surface including buildings, vegetation, and the ground. Digital elevation models (DEMs) are one of many products...
What is a digital elevation model (DEM)?
A Digital Elevation Model (DEM) is a representation of the bare ground (bare earth) topographic surface of the Earth excluding trees, buildings, and any other surface objects. DEMs are created from a variety of sources. USGS DEMs used to be derived primarily from topographic maps. Those are being systematically replaced with DEMs derived from high-resolution lidar and IfSAR (Alaska only) data...
What is the projection, horizontal datum, vertical datum, and resolution for a USGS digital elevation model (DEM)?
Projection: 3DEP DEMS have different projections/coordinate systems depending on the product: 1/3-, 1-, and 2-arc-second (also the discontinued 1/9-arc-second) DEMs are not projected. They are all in geographic coordinates (latitude/longitude). 5-meter DEMs (Alaska only) are Alaska Albers Equal Area. 1-meter DEMs are in Universal Transverse Mercator (UTM). Original Product Resolution (OPR) DEMs –...
How do I report errors in 3D Elevation Program (3DEP) elevation data?
If you think you’ve found an error in USGS elevation data, please send an email to tnm_help@usgs.gov. We will add the reported information to our "Digital Elevation Model Issues" data log for further analysis and possible correction. Spikes, pits, seam-line anomalies, and other data errors are of concern to us. We are working to correct or minimize known issues, but it will take some time. Errors...
What is Lidar data and where can I download it?
Light Detection and Ranging (lidar) is a technology used to create high-resolution models of ground elevation with a vertical accuracy of 10 centimeters (4 inches). Lidar equipment, which includes a laser scanner, a Global Positioning System (GPS), and an Inertial Navigation System (INS), is typically mounted on a small aircraft. The laser scanner transmits brief pulses of light to the ground...
Where can I find 3D Elevation Program (3DEP) product updates and status maps?
3D Elevation Program (3DEP) product updates and status maps are available at these sites: Updates The National Map Data Delivery News Subscribe to Simple Notification Services to receive emails regarding changes to the status of The National Map Services Status Maps The National Map Download Client – Click “Show” below each elevation product LidarExplorer – Lidar point cloud only DEM Availability...
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