What is the vertical accuracy of the 3D Elevation Program (3DEP) DEMs?

The USGS 3D Elevation Program (3DEP) is in the process of collecting high-quality lidar and  IfSAR (for Alaska) coverage for all of the United States and its territories. As this new data becomes available, legacy Digital Elevation Models (DEMs) are being systematically replaced with high-resolution DEMs produced almost entirely from the lidar and ifsar data.  Legacy DEMs were produced from...

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...

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...

The National Map’s   Elevation Point Query Service (EPQS) returns elevations that are interpolated from the 3DEP dynamic elevation service. This is a web coverage service (WCS) that includes multiple resolutions of DEMs including 1 meter resolution lidar-based DEMs where available, and 1/3 arc-second seamless DEMs. The accuracy of the elevations returned by EPQS will vary according to the source...