Elevation - 7 of 37

Elevation FAQs - 37 Found

How are the highest quality elevation data sources selected for deriving 3DEP seamless DEMs?

There are frequently multiple sources of elevation data held by the USGS that cover a given geographic location. In generation of the seamless DEMs, preference is given to that which is the most detailed and up-to-date, unless there are overriding quality concerns. Data source requirements for the seamless layers are listed below:

  • Bare-earth elevation surface
  • Highest resolution USGS source for an area
  • Most recent USGS source for an area
  • Most accurate USGS source for an area
  • Freely redistributable
  • Hydro flattened*
  • Must not be hydro-enforced or hydro-conditioned*.

* National Map seamless layers represent a topographic surface. Hydro-flattening is necessary for any dataset to be considered for the seamless layers. Hydro-enforced or hydro-conditioned DEM data create surfaces that are not suitable for topographic mapping, and are not considered suitable for seamless DEMs.

Tags: Maps, Topographic, Data Products