Shuttle Radar Topography Mission (SRTM) digital elevation data were collected by a modified radar system that flew on board the Space Shuttle Endeavour in February 2000, using a technique known as Interferometric Synthetic Aperture Radar (ifsar) to gen
Send an e-mail message to tnm_help@usgs.gov and 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
The standard 3DEP DEMs serve as the elevation layer of The National Map, and provide elevation information for earth science studies and mapping applications in the United States.
The 3DEP DEMs are updated continuall
Yes, lidar data are represented as a cloud of variably spaced point locations (x,y,z) of any terrestrial target reflecting the laser pulse. In addition to bare-earth, the point cloud will typically include buildings, trees, towers, and powerlines.
Specific data for average (or mean) county elevations for the United States are not presently available from the USGS. You can extract an elevation for the centroid of each county polygon using Esri ArcGIS software (see procedures below).
Specific data for current mountain peak elevations do not exist at USGS other than what was previously published in an Elevations and Distances in the United States booklet.
Yes, the file naming convention in the ned19readme.pdf should be as follows where corrections are noted in bold type:Example:  ned19_n40x50_w074x50_nj_mercerco_2008     ned19 = Elevation Product