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The National Map Seamless Digital Elevation Model Specifications The National Map Seamless Digital Elevation Model Specifications Chapter 9 of Section B, U.S. Geological Survey Standards, of Book 11, Collection and Delineation of Spatial Data Techniques and Methods 11–B9 U.S. Department of the Interior U.S. Geological Survey Cover: Tahoe Basin Lidar Project—A view of the seamless digital elevation model (DEM) in the Desolation Wilderness of the Sierra Nevada mountain range, looking northeastward over Mount Ralston toward Mount Tallac and Lake Tahoe, shows the difference in feature crispness in the area derived from lidar (area north of blue line), as compared to the surrounding region. Note that the DEM itself does not vary in resolution across the image. The National Map Seamless Digital Elevation Model Specifications By Christy-Ann M. Archuleta, Eric W. Constance, Samantha T. Arundel, Amanda J. Lowe, Kimberly S. Mantey, and Lori A. Phillips Chapter 9 of Section B, U.S. Geological Survey Standards, of Book 11, Collection and Delineation of Spatial Data Techniques and Methods 11–B9 U.S. Department of the Interior U.S. Geological Survey U.S. Department of the Interior RYAN K. ZINKE, Secretary U.S. Geological Survey William H. Werkheiser, Acting Director U.S. Geological Survey, Reston, Virginia: 2017 For more information on the USGS—the Federal source for science about the Earth, its natural and living resources, natural hazards, and the environment—visit https://www.usgs.gov or call 1–888–ASK–USGS. For an overview of USGS information products, including maps, imagery, and publications, visit https://store.usgs.gov/. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. Although this information product, for the most part, is in the public domain, it also may contain copyrighted materials as noted in the text. Permission to reproduce copyrighted items must be secured from the copyright owner. Suggested citation: Archuleta, C.M., Constance, E.W., Arundel, S.T., Lowe, A.J., Mantey, K.S., and Phillips, L.A., 2017, The National Map seamless digital elevation model specifications: U.S. Geological Survey Techniques and Methods, book 11, chap. B9, 39 p., https://doi.org/10.3133/tm11B9. ISSN 2328-7055 (online) iii Contents Abstract ...........................................................................................................................................................1 Introduction.....................................................................................................................................................1 Purpose and Scope .......................................................................................................................................1 Applicability ....................................................................................................................................................1 Product Descriptions............................................................................................................................1 Requirement Terminology .............................................................................................................................3 Background for The National Map Seamless Digital Elevation Model Datasets ...............................3 Product Specifications..................................................................................................................................4 Source Data Requirements .................................................................................................................4 Spatial Reference System ...................................................................................................................4 Distribution Tiling ..................................................................................................................................4 Horizontal Resolution ...........................................................................................................................4 Horizontal Accuracy .............................................................................................................................4 Lidar Source Data .................................................................................................................................4 Legacy Topographic Data ....................................................................................................................5 Vertical Accuracy .................................................................................................................................5 Digital Elevation Model Surface Treatment ......................................................................................5 Georeferencing Information ...............................................................................................................5 Data Source and Tile Dates.................................................................................................................5 Distribution and Supporting File Formats .........................................................................................5 Void Areas ..............................................................................................................................................5 Metadata ................................................................................................................................................6 Spatial Metadata...................................................................................................................................6 Quality Assurance and Control ...........................................................................................................7 Maintenance...................................................................................................................................................7 Selected References .....................................................................................................................................7 Glossary ...........................................................................................................................................................9 Appendixes ...................................................................................................................................................13 Appendix 1. Seamless Digital Elevation Model Metadata Example ................................................14 Appendix 2. Seamless Digital Elevation Model Spatial Metadata Data Dictionary—1/3-Arc-Second, 1-Arc-Second, and 2-Arc-Second .........................................26 iv Figures 1. Map showing seamless digital elevation model datasets are produced in 1-degree by 1-degree tiles with a 6-pixel overlap between tiles ...........................................................2 2. Graphic showing seamless digital elevation model nested resolution for Denali, Alaska .............................................................................................................................................3 3. Example of georeferencing information in metadata file ......................................................5 4. Example showing spatial metadata for available seamless digital elevation model (DEM) tiles as of January 26, 2016, for the Newburg, Missouri, DEM area ........................6 Tables Table 1. Prioritized list of data sources for seamless digital elevation models ...............................2 Conversion Factors [International System of Units to U.S. customary units] Multiply By To obtain Length centimeter (cm) 0.3937 inch (in.) meter (m) 39.37/12 foot (ft) meter (m) 1/0.3048 International foot (ft) meter (m) 1.094 yard (yd) kilometer (km) 0.6214 mile (mi) Area square meter (m2) 0.0002471 acre square kilometer (km2) 247.1 acre square meter (m2) 10.76 square foot (ft2) square kilometer (km2) 0.3861 square mile (mi2) Datum Vertical coordinate information is referenced to the North American Vertical Datum of 1988 (NAVD 88). Horizontal coordinate information is referenced to the North American Datum of 1983 (NAD 83). Elevation, as used in this specification, refers to the distance above the geoid, unless specifically referenced to the ellipsoid. v Abbreviations 3D 3-dimensional 3DEP 3D Elevation Program CONUS conterminous United States DEM digital elevation model FGDC Federal Geographic Data Committee GPS Global Positioning System ifsar interferometric synthetic aperture radar IMU Inertial Measurement Unit lidar light detection and ranging NPD nominal pulse density NPS nominal pulse spacing QA quality assurance QC quality control USGS U.S. Geological Survey UTM Universal Transverse Mercator XML Extensible Markup Language The National Map Seamless Digital Elevation Model Specifications By Christy-Ann M. Archuleta, Eric W. Constance, Samantha T. Arundel, Amanda J. Lowe, Kimberly S. Mantey, and Lori A. Phillips Abstract interferometric synthetic aperture radar (ifsar), or other input data. For more information on lidar procurement specifica- This specification documents the requirements and stan- tions, refer to Heidemann (2014). dards used to produce the seamless elevation layers for The National Map of the United States. Seamless elevation data are available for the conterminous United States, Hawaii, Alaska, Applicability and the U.S. territories, in three different resolutions—1/3-arc- second, 1-arc-second, and 2-arc-second. These specifications The specifications in this report are applicable to the
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