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Location Science Improves Everyday Life
This short video explores some of the ways that location science improves everyday life. It follows two characters, Jane and John, through the course of a typical day. Jane has a smooth trouble-free day fishing with friends, thanks in part to accurate location surveys. John, on the other hand, has an awful day traced to inaccurate surveys and out-of-date maps.
Gravity for Geodesy II: Applications
Gravity is an important part of geodesy, with implications for height measurements and many other applications. In this module, we explore the concept of equipotential surfaces and relate them to gravity. Then we discuss geodetic applications that rely on accurate gravity measurements, including leveling surveys and floodplain mapping. We introduce a special surface based on gravity, called the gravimetric geoid, and explain why we want to use it as a reference datum. We discuss how to measure Earth’s gravity and introduce you to the National Geodetic Survey’s GRAV-D project, including how and ...
Foundations of Global Navigation Satellite Systems (GNSS)
This lesson provides a technical introduction to Global Navigation Satellite Systems (GNSS), covering theory, procedures, and accuracy issues. Aimed at professionals in a “geospatial science” field, including engineers, surveyors, meteorologists, geographers and GIS professionals, it will also be useful for emergency managers, and technically-inclined members of the general public with appropriate math and/or science background. For those who may currently see GPS/GNSS as a “black box”, this 1.5 hour lesson provides an understanding of the underlying principles and concepts to support correctl ...
Gravity for Geodesy I: Foundations
The first of a two-part series, this 40-50 minute non-narrated interactive lesson is intended to help professionals with basic science background better understand the Earth’s gravity field and what causes its variations. Of particular interest to earth/physical scientists as well as surveying engineers, this lesson covers Newton’s laws with a focus on Earth’s gravity field as it applies to geodesy. After a review of the basics of Newtonian gravitation and gravity, it explores how density, altitude, and latitude affect gravity.
NOAA’s VDatum: Transforming Heights between Vertical Datums
Produced in collaboration between NOAA’s National Geodetic Survey (NGS) and The COMET Program, this video explains NOAA’s VDatum tool and its role in facilitating height transformations between vertical datums including tidal, orthometric, and ellipsoidal datums. It also provides an overview of different types of vertical datums and how they may be used for different applications with a focus on coastal areas and navigation services. Leaders from NOAA as well as other government agencies such as the U.S. Geological Survey (USGS), the Federal Emergency Management Agency (FEMA), and the U.S. Arm ...
Best Practices for Minimizing Errors during GNSS Data Collection
Aimed at surveyors and GIS professionals who use geodetic-quality GNSS equipment to determine positions for land planning, coastal monitoring and other purposes, this video covers best practices for reducing errors in the areas of: 1. location and environment, 2. equipment setup and 3. observation times and accuracy checks. This resource is hosted on COMET's YouTube Channel.
The Importance of Accurate Coastal Elevation and Shoreline Data
Produced in collaboration between NOAA’s National Geodetic Survey (NGS) and The COMET Program, this video explains the role of topo-bathy lidar products in NOAA’s mapping and charting program, and how these products provide a critical dataset for coastal resilience, coastal intelligence, and place-based conservation. Federal, state and local decision-makers, coastal zone managers, community planners as well as general and scientific users of mapping products will find this 4-minute video helpful for understanding the benefits of coastal elevation data produced by NGS. This resource is hosted o ...
Geospatial Infrastructure for Coastal Communities: Informing Adaptation to Sea Level Rise
Aimed at community planners, emergency managers, and other coastal zone decision-makers this video will explain how using geospatial information already available through NOAA, combined with strategic local investments in infrastructure can provide communities with the data needed to confidently plan for future sea-level changes. This resource is hosted on COMET's YouTube Channel.
Two Right Feet? Understanding the Difference Between U.S. Survey Feet and International Survey Feet
This video explains the difference between the U.S. survey foot (sFT) and the international survey foot (iFT) and the importance of this distinction when working with map projections. It will be helpful to surveyors, planners and anyone who needs to convert map coordinates from meters to feet. This resource is hosted on COMET's YouTube Channel.
Introduction to Geodesy and Mapping
This lesson covers the topics of geodesy, datums, map projections, and map coordinate systems. Geodesy addresses the shape of the earth: the topographic surface, geoid, and best-fit ellipsoid. Datums addresses the position and orientation or the best-fit ellipsoid and the resulting coordinates. Map projections addresses the different ways to project an ellipsoidal datum onto a flat surface. Each projection has unique properties and each has pros and cons. Coordinate systems addresses the different ways that a rectangular coordinate system can be superposed on latitude-longitude graticule.
Precision and Accuracy in Geodetic Surveying
This brief video focuses on the importance of both precision and accuracy in geodetic surveying and the difference between them. Produced in collaboration between NOAA’s National Geodetic Survey and The COMET Program, this video is aimed at surveying professionals, planners, policy-makers and others who use mapping products. The video emphasizes that the accuracy of survey measurements should always be verified by relating measurements to a known reference system such as the National Spatial Reference System in the United States. This resource is hosted on COMET's YouTube Channel.
An Introduction to Geodetic Datums
This series of short videos, produced in collaboration between NOAA’s National Geodetic Survey and The COMET Program, provides an introduction to geodetic datums for anyone who uses mapping products or other geo-spatial tools. 1. What are Geodetic Datums? (4:36) In this video we explain the basic concepts behind geodetic datums, where they are used, and why it is important to know about and use the correct datums. 2. How Were Geodetic Datums Established? (3:12) In this video, we explore the history of geodetic datums in the United States, and how they were established at a national level to as ...
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