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 that can be derived from lidar data, though they can also be derived from other sources. DEMs are digital representations of the earth’s topographic surface. They’re a “bare-earth” product because they do not include surface features like buildings and vegetation. 

A high-resolution DEM can be derived from lidar point-cloud data by stripping away the surface features and sampling the ground elevation in uniform increments to produce a bare earth model. 

The USGS is in the process of replacing all of our legacy DEMs with DEMs derived from lidar and IfSAR (Alaska only) data. 

Learn more: 

Divided image with tree-covered slope on one side and the treeless, bare earth on the other side revealing landslides

By processing lidar point clouds to bare earth DEMs, the vegetation is stripped away to reveal past landslides and steep slopes at risk of failure masked by forested canopies. In dense forests, landslides, especially ones in the distant past, may be invisible on aerial images and hard to detect from the ground.

(Public domain.)

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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: 3DEP Product Availability 3DEP Data Acquisition Status Maps Acquire updated products through The National Map Downloader , The National Map Services , or through a bulk data request . 3D Elevation Program News The National Map Data Delivery News Subscribe to...

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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...

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...
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August 28, 2020

Lidar Base Specification 2020 rev. A is now available

The 3DEP Lidar Base Specification 2020 rev. A is now available! 

This release of the Lidar Base Specification (LBS) introduces a new version naming convention to aid in tracking revisions and to clarify the year of release. This and following releases will labeled with "YYYY rev. L" where YYYY is the year of the release and L is a letter corresponding to the order of the release. 

Date published: October 23, 2019

USGS Digital Elevation Models (DEM) Switching to New Distribution Format

In support of ongoing efforts to provide efficient, cloud ready, open data formats, the U.S. Geological Survey National Geospatial Program is announcing plans to migrate its 3D Elevation Program (3DEP) Digital Elevation Models (DEM) to a new data delivery format called Cloud Optimized Geotiff (COG) during the first half of fiscal year 2020.

Date published: February 7, 2019

USGS 3DEP Lidar Point Cloud Now Available as Amazon Public Dataset

The USGS 3D Elevation Program (3DEP) is excited to announce the availability of a new way to access and process lidar point cloud data from the 3DEP repository.

Date published: August 8, 2018

New Elevation Map Service Available From the USGS 3D Elevation Program

The USGS 3D Elevation Program (3DEP) announces the availability of a new dynamic map service.

Date published: June 26, 2018

The 3D Elevation Program Distributing Lidar Data in LAZ Format

In support of ongoing efforts to provide efficient, cloud ready, open data formats for the use of lidar data, the USGS National Geospatial Program and its associated 3D Elevation Program is transitioning all of its lidar data distribution files to LAZ format by September 30, 2018.

Date published: May 23, 2018

Keeping Current with Map Services Made Easier

The National Map provides a new Simple Notification Service and has new URLs for some of its thematic cartographic map services.

Date published: January 23, 2017

Maps Made With Light Show the Way

The topic, officially, was water. But during a scientific conference in Butte, Montana, in 2013, earthquake expert Michael Stickney glimpsed something unexpected in a three-dimensional lidar image of the Bitterroot Valley in nearby Missoula.

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Automated GNIS Summit Core Generation
July 26, 2018

Automated GNIS Summit Core Generation

A few summit cores delineated by the National Terrain Mapping program in the Blue Ridge province, North Carolina. While many summits are mapped via the Geographic Names Information System points, boundaries for these features don't exist. This program is automating procedures to do so for the whole nation.

May 11, 2018

New 3D Model of the Drained Crater at Pu‘u ‘Ō‘ō

During an overflight on May 11, we collected thermal images of the crater at Pu‘u ‘Ō‘ō and created an updated 3D model of the crater geometry. The collapse on April 30 produced a large cavity, with the deepest point roughly 350 m (1150 feet) below the crater rim.

November 18, 2004

PubTalk 11/2004 — From Plane Tables to Pixels

The Revolution in Mapping at the U.S. Geological Survey

by Susan P. Benjamin, Research Geographer

  • Mapping the United States in the 19th century was arduous, dangerous work; flash floods, bears, and bandits were just a few hazards
  • By the mid-20th century, aerial photography, photogrammetry, and stereophoto pairs, allowed