NGP Standards and Specifications

Lidar Base Specification

The Lidar Base Specification, LBS, is the set of specifications and requirements governing the collection and processing of lidar data for the 3D Elevation Program (3DEP) and inclusion into The National Map. 

Updates to the Lidar Base Specification

The 3DEP Lidar Base Specification is updated through the Elevation Specifications Review Board (ESRB) and the 3DEP Working Group. Once updates are approved, they are incorporated into the LBS and published to the web at the Lidar Base Specification Online site. The most recent updates incorporate Bridge and Saddle Requirements that have been in practice for several years. This update adds the following specifications:

  • All instructions and requirements regarding the use of breaklines also applies to non-hydrographic terrain generation below bridges.
  • Any breaklines used to enforce a logical terrain surface below a bridge shall be considered a required deliverable.
  • The bare-earth surface below the bridge shall be a continuous, logical interpolation of the apparent terrain lateral to the bridge deck.
  • Where abutments are clearly visible, the bare-earth interpolation shall begin at the junction of the bridge deck and approach structure. Where this junction is not clear, the contractor shall use their best judgement to delineate the separation of below-bridge terrain from elevated bridge surface.
  • Streams, rivers, and water bodies meeting the criteria for hydro-flattening shall be monotonically continuous where bridge decks have been removed.

The USGS intends to use this specification to acquire and procure lidar data and to create consistency across all USGS–NGP and partner-funded lidar collections, in particular those that support the standard national DEM available through The National Map and 3DEP.

This base specification covers four different data QLs and defines minimum parameters for acceptance of the acquired lidar data for each QL. Local conditions in any given project, specialized applications for the data, or the preferences of cooperators may mandate more stringent requirements.

The first version of the Lidar Base Specification, v. 1.0, was published in August 2012. Since then, there have been four revisions (versions 1.1, 1.2, 1.3, and 2.0) with publication dates of October 2014, November 2014, February 2018, and September 2018. The first three versions were authored by Hans Karl Heidemann. 

If you have questions or would like more information about these specifications, please contact The National Map Help.