Elevation - 3 of 39

Elevation FAQs - 39 Found

How accurate are spot elevation query values?

The NED Point Query Service uses the National Elevation Dataset (NED) 1/3 arc-second layer from the U.S. Geological Survey (USGS) as its source. Spot elevation query values from the NED are not official and do not represent precisely measured or surveyed values. Data are extracted from digital elevation models for a given set of coordinates and might differ from elevations cited in other sources, including those published on USGS topographic maps. Published map data represent precisely surveyed points that often are marked by a benchmark or triangle on the map and a monument physically anchored into the ground at the site. Variances between the elevation data and other sources generally arise from acceptable tolerances and will be most evident for features such as mountain peaks or summits, where precision is of more concern, and where the local relief (rate of change of elevation) is more prominent. If an elevation value for a particular feature seems significantly inaccurate, the digital elevation model data for those coordinates may also be incorrect. For most purposes, queried elevation values are sufficiently accurate, although efforts are continuously being made to improve accuracy of NED data. For applications requiring more accurately surveyed elevations of mountain peaks or summits, and other spot elevations at benchmark monuments or control points, please reference the National Geodetic Survey datasheets.

Tags: Maps, Coordinates, Topographic, Recreation, Quadrangle, GeoPDF, Scale