Title: Land Surveying Information - NGS INFO - About Us - National Geodetic Survey URL Source: https://geodesy.noaa.gov/INFO/geodesy.shtml Markdown Content: [Skip to main content](https://geodesy.noaa.gov/INFO/geodesy.shtml#main-content) [](https://www.noaa.gov/ "NOAA Home Page") Toggle navigation[NGS Home](https://geodesy.noaa.gov/index.shtml) * [About NGS](https://geodesy.noaa.gov/INFO/geodesy.shtml#) * [What We Do](https://geodesy.noaa.gov/INFO/WhatWeDo.shtml) * [Mission and Strategic Plan](https://geodesy.noaa.gov/web/about_ngs/info/mission-strategic-planning.shtml) * [NGS Leadership](https://geodesy.noaa.gov/INFO/leadership.shtml) * [Programs and Products](https://geodesy.noaa.gov/INFO/programs-products.shtml) * [Geodetic Advisors](https://geodesy.noaa.gov/ADVISORS/index.shtml) * [NGS History](https://geodesy.noaa.gov/INFO/history/) * [Policies](https://geodesy.noaa.gov/INFO/Policy/) * [Activities in My Area](https://geodesy.noaa.gov/INFO/activities.shtml) * [Grant Opportunities](https://geodesy.noaa.gov/grant-opportunities/index.shtml) * [Contracting Opportunities](https://geodesy.noaa.gov/ContractingOpportunities/) * [Student Opportunities](https://geodesy.noaa.gov/student-opportunities/index.shtml) * [FAQ](https://geodesy.noaa.gov/faq.shtml) * [Contact Us](https://geodesy.noaa.gov/INFO/NGSinfo.shtml) * [Data & Imagery](https://geodesy.noaa.gov/INFO/geodesy.shtml#) * [OPUS Share](https://geodesy.noaa.gov/OPUS/view.jsp) * [Survey Mark Datasheets](https://geodesy.noaa.gov/datasheets/) * [NGS Web Map](https://geodesy.noaa.gov/datasheets/ngs_map/) * [NOAA CORS Network (NCN)](https://geodesy.noaa.gov/CORS/) * [Antenna Calibration Data](https://geodesy.noaa.gov/ANTCAL/) * [Remote Sensing](https://geodesy.noaa.gov/RSD/rsd_home.shtml) * [Storm Imagery](https://storms.ngs.noaa.gov/) * [Coastal Imagery](https://geodesy.noaa.gov/web/APOS2/APOS.shtml) * [Shoreline Data Explorer](https://geodesy.noaa.gov/RSD/cmp_data.shtml) * [Orthomosaics](https://coast.noaa.gov/dataviewer/#/imagery/search/where:projectid=1020) * [Lidar](https://coast.noaa.gov/dataviewer/#/lidar/search/where:projectid=24) * [Aeronautical Data](https://geodesy.noaa.gov/AERO/aero.html) * [Gravity Data](https://geodesy.noaa.gov/GRAV-D/data_products.shtml) * [Tools](https://geodesy.noaa.gov/INFO/geodesy.shtml#) * [Process GPS Data (OPUS)](https://geodesy.noaa.gov/OPUS/) * [Coordinate Conversion and Transformation Tool (NCAT)](https://geodesy.noaa.gov/NCAT/) * [Geodetic Tool Kit](https://geodesy.noaa.gov/TOOLS/) * [Geodetic Software](https://geodesy.noaa.gov/PC_PROD/) * [Web Services](https://geodesy.noaa.gov/web_services/) * [Vertical Datum Conversions (VDATUM)](http://vdatum.noaa.gov/) * [GPS Toolbox](https://geodesy.noaa.gov/gps-toolbox/) * [GEOID18 Computation](https://geodesy.noaa.gov/GEOID/GEOID18/computation.html) * [Adjust Leveling (LOCUS)](https://geodesy.noaa.gov/locus/) * [Horizontal Time-Dependent Positioning (HTDP)](https://geodesy.noaa.gov/TOOLS/Htdp/Htdp.shtml) * [Surveys](https://geodesy.noaa.gov/INFO/geodesy.shtml#) * [Survey Project Proposal Form](https://geodesy.noaa.gov/SurveyProposal/) * [OPUS Share](https://geodesy.noaa.gov/OPUS/about.jsp#sharing) * [Mark Recovery](https://geodesy.noaa.gov/surveys/mark-recovery/index.shtml) * [User-submitted Survey Projects (Bluebooking)](https://geodesy.noaa.gov/FGCS/BlueBook/) * [Geoid Slope Validation Survey (GSVS)](https://geodesy.noaa.gov/GEOID/GSVS/) * [Calibration Base Lines (CBLs)](https://geodesy.noaa.gov/CBLINES/calibration.shtml) * [GPS on Bench Marks](https://geodesy.noaa.gov/GPSonBM/) * [GRAV-D](https://geodesy.noaa.gov/GRAV-D/) * [Height Modernization](https://geodesy.noaa.gov/heightmod/) * [Leveling](https://geodesy.noaa.gov/leveling/) * [Science & Education](https://geodesy.noaa.gov/INFO/geodesy.shtml#) * [Datums and Reference Frames](https://geodesy.noaa.gov/datums/index.shtml) * [New Datums](https://geodesy.noaa.gov/datums/newdatums/index.shtml) * [Research](https://geodesy.noaa.gov/research/) * [Geoid Models](https://geodesy.noaa.gov/GEOID/) * [Conferences/Training](https://geodesy.noaa.gov/web/science_edu/training/) * [Upcoming and Recent NGS Presentations](https://geodesy.noaa.gov/INFO/conferences.shtml) * [Educational Videos](https://geodesy.noaa.gov/corbin/class_description/NGS_Video_Library.shtml) * [Online Lessons](https://geodesy.noaa.gov/web/science_edu/online_lessons/index.shtml) * [Webinar Series](https://geodesy.noaa.gov/web/science_edu/webinar_series/) * [Presentation Library](https://geodesy.noaa.gov/web/science_edu/presentations_library/) * [Publication Library](https://geodesy.noaa.gov/library/) * [Commemorative Marks](https://geodesy.noaa.gov/commemorative/index.shtml) * [Applications of Geodesy](https://geodesy.noaa.gov/INFO/applications-of-geodesy.shtml) * ## About Us * [What we do](https://geodesy.noaa.gov/INFO/WhatWeDo.shtml) * [GNSS & GPS Data](https://geodesy.noaa.gov/INFO/gnss-gps-data.shtml) * [Remote Sensing](https://geodesy.noaa.gov/INFO/remote-sensing.shtml) * [Land Surveying](https://geodesy.noaa.gov/INFO/land-surveying.shtml) * [Geodesy](https://geodesy.noaa.gov/INFO/geodesy.shtml) * [Training & Education](https://geodesy.noaa.gov/INFO/training-education.shtml) * [Datums & Transformations](https://geodesy.noaa.gov/INFO/datums-transformations.shtml) * [Activities in my area](https://geodesy.noaa.gov/INFO/activities.shtml) * [Applications of Geodesy](https://geodesy.noaa.gov/INFO/applications-of-geodesy.shtml) * [Mission & Strategic Plan](https://geodesy.noaa.gov/web/about_ngs/info/mission-strategic-planning.shtml) * [NGS Facts](https://geodesy.noaa.gov/INFO/facts/index.shtml) * [Policies](https://geodesy.noaa.gov/INFO/Policy/index.shtml) * [Programs & Products](https://geodesy.noaa.gov/INFO/programs-products.shtml) * [NGS History](https://geodesy.noaa.gov/INFO/history/) * [FAQs](https://geodesy.noaa.gov/faq.shtml) * [Contact Us](https://geodesy.noaa.gov/INFO/NGSinfo.shtml) * [![Image 2: gov delivery icon](https://geodesy.noaa.gov/wp-content/uploads/2018/02/govdelivery-rsz.png) ## Subscribe for email notifications](https://geodesy.noaa.gov/INFO/subscribe.shtml) [](https://geodesy.noaa.gov/INFO/subscribe.shtml) # Geodesy Geodesy is the science of accurately measuring and understanding three fundamental properties of the Earth: its geometric shape, its gravity field, and its orientation in space, as well as the changes of these properties with time. * * * ## Data **Data available** includes high-accuracy coordinates (latitude, longitude, and height) at continuously operating GPS sites. * [Continuously Operating Reference Stations (CORS)](https://geodesy.noaa.gov/CORS/index.shtml): Partners maintain sites, then NGS processes continuous GPS data and publishes accurate coordinates. * [Orbits](https://geodesy.noaa.gov/orbits/index.shtml): NGS has contributed to enabling such GPS/GNSS access to the national spatial reference system by computing high-accuracy GPS orbits. * [Gravity data](https://geodesy.noaa.gov/GRAV-D/data_products.shtml): airborne and terrestrial survey information, gravity data, and gravity-based geoids or datums ![Image 3](https://geodesy.noaa.gov/wp-content/uploads/2018/06/science-cors-2.jpg) * * * ## Models and Tools **Tools and models available** to process GPS data and transform coordinates (latitude, longitude, and height) across various reference frames. * [Antenna Calibration](https://geodesy.noaa.gov/ANTCAL/): Accounting for each antenna’s properties significantly improves post-processed GPS coordinates. * [Transformation tools (geodetic toolkit)](https://geodesy.noaa.gov/TOOLS/index.shtml): Transformation tools are available to transform data referenced from one geodetic datum to another. * [Geoid Models](https://geodesy.noaa.gov/GEOID/index.shtml): In combination with GPS derived heights, an accurate geoid model will help determine the direction water flows. ![Image 4](https://geodesy.noaa.gov/wp-content/uploads/2018/06/models-2.jpg) * * * ## Survey **Surveys** refer to data collection efforts. Learn about NGS survey projects or submit your own to share with NGS and others. * [New Datums](https://geodesy.noaa.gov/datums/newdatums/index.shtml): The North American Datum of 1983 (NAD 83) and the North American Vertical Datum (NAVD 88) will be replaced in 2022 to improve alignment with reference frames and improve accuracy of GPS-derived heights. * [GRAV-D](https://geodesy.noaa.gov/GRAV-D/index.shtml): The project collects airborne gravity data, which will help improve future geoid models, and ultimately replace NAVD 88. * [Geoid Slope Validation Survey (GSVS)](https://geodesy.noaa.gov/GEOID/GSVS14/index.shtml): These surveys are conducted to test the accuracy of the gravimetric geoid model, which will be the basis for the next vertical datum. * [International Earth Rotation & Reference System Service (IERS) Site Survey (ISS) Program](https://geodesy.noaa.gov/corbin/iss/index.shtml): NGS is conducting and reporting on local tie vector information for co-located geodetic technique instruments. ![Image 5](https://geodesy.noaa.gov/wp-content/uploads/2018/06/grav-d-2.jpg) [NOS Home](https://oceanservice.noaa.gov/)![Image 6: bullet](https://geodesy.noaa.gov/ngsstandard/images/redbullet.gif)[Privacy](https://geodesy.noaa.gov/privacy.shtml)![Image 7: bullet](https://geodesy.noaa.gov/ngsstandard/images/redbullet.gif)[Feedback](https://geodesy.noaa.gov/survey.shtml)![Image 8: bullet](https://geodesy.noaa.gov/ngsstandard/images/redbullet.gif)[Disclaimer](https://geodesy.noaa.gov/disclaimer.html)![Image 9: bullet](https://geodesy.noaa.gov/ngsstandard/images/redbullet.gif)[USA.gov](https://www.usa.gov/)![Image 10: bullet](https://geodesy.noaa.gov/ngsstandard/images/redbullet.gif)[Ready.gov](https://www.ready.gov/)![Image 11: bullet](https://geodesy.noaa.gov/ngsstandard/images/redbullet.gif)[Information Quality](https://www.noaa.gov/organization/information-technology/policy-oversight/information-quality)![Image 12: bullet](https://geodesy.noaa.gov/ngsstandard/images/redbullet.gif)[Site Map](https://geodesy.noaa.gov/sitemap.xml)![Image 13: bullet](https://geodesy.noaa.gov/ngsstandard/images/redbullet.gif)[Contact Us](https://geodesy.noaa.gov/cgi-bin/redirectNOAA.prl?u=ngs.infocenter)