Digital Elevation Model Changes
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.
The USGS is making this change to improve product processing time, storage, and to support new and evolving cloud processing capabilities for users. COG is an open standard, directly accessible and cloud ready-to-use format. Legacy software can read the file with no additional modifications because the underlying file format of a COG is a geotiff.
Online software systems can stream any portion of the data needed, improving processing times and allowing workflow flexibility that was not possible when DEMs were stored inside ZIP files. Since users can stream the data, they do not need to keep their own local copy, therefore reducing data redundancy and overall storage requirements. COG formats can also be translated into other raster formats if needed through open source GDAL tools.
Currently, the USGS serves standard DEMs in a variety of formats (ArcGrid, IMG, Grid float). After the transition to COG format for each product is complete, all other existing legacy formats will be removed from distribution.
The goal of 3DEP is to complete acquisition of nationwide lidar (IfSAR in AK) by 2023 to provide the first-ever national baseline of consistent high-resolution elevation data – both bare earth and 3D point clouds – collected in a timeframe of less than a decade.
For any questions, comments, or concerns regarding this update, contact tnm_help@usgs.gov.
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