Geodesy Visualizations

Mechanics behind Geodesy Tools

Satellite Orbits

Orbiting Earth (more info) Flash animation comparing two typical satellite orbit patterns: geostationary and polar orbits.

Global Positioning Systems (GPS) ( This site may be offline. ) View an animated Flash slide show explaining how GPS works. GPS operates because of three interconnected segments: the satellite, ground control, and user segments. This animation focuses on the satellite and user segments, briefly touching upon how the satellite signal is processed to produce positional values in hand-held GPS units. Note that the accuracy claimed for handheld GPS units 100 m is now routinely exceeded. With the turning off of selective availability, today's GPS handheld units usually get accuracies of better than 10 meters. Note that the video loads slowly.


How Do Global Positioning Systems, or GPS, Work? (more info) A movie of students interviewing a NASA expert, who explains basic GPS principles. Simple, but clear description of how trilateration works with a two-dimensional model vs 3-D. Appropriate for the 6-8 grade range.
IRIS - GPS- Measuring Plate Motion (more info) Well organized collection animations and videos (with descriptions) of how GPS can be used to measure plate motion. The videos use the Pacific NW as an example to understand this topic. Videos can be downloaded along with a pdf of the classroom activity.


InSAR Unavco thumbnail 2008 Unavco short course, InSAR for Geoscientists, provides files containing excellent visuals of the inter-workings of InSAR satellites and data output. In particular, Principles and Theory of Radar Interferometry powerpoint presentation by Paul Rosen of NASA's Jet Propulsion Laboratory (JPL) is visually rich and contains information about the fundamentals of radar imaging, the a geometry of interferometric phase measurements, principles of interferometric correlation, and explains how the data is then processed. Also touches on X-band, L-band, and C-band wavelengths, and how each can be useful.

Very Long Baseline Interferometry (VLBI) Introduction ( This site may be offline. ) A labeled conceptual/explanatory diagram. Text describes the mechanics of VLBI and has links to information on the history of VLBI, current VLBI usage (which is outdated to the 1990's), and the future of the project. Though some information is dated, the visuals and conceptual information is useful and accurate.

NASA JPL How InSAR Works (more info) NASA video explaining how InSAR (Interferometric Synthetic Aperture Radar) works and why it is useful


DORIS diagrams showing the instrument layout, receiving stations, and a representation of data transfer.

Terrestrial Reference Frame/ Geoid

( This site may be offline. ) 3D tool to display and explore geodesy information. Data sets include Seismology, Geodynamics (GPS velocities, plate boundaries, the geoid, InSAR images, etc.), Geophysics, geologic maps and cross sections, and more.

NOAA Geoid and Deflection Models (more info) Geoid and Deflection Models of the contiguous US, Alaska, Hawaii, Mexico, Caribbean, Guam, and American Samoa.

Gravity Data

Global Seafloor Topography from Satellite Altimetry (more info) Bathymetric maps of the global seafloor derived from a combination satellite altimetry and shipboard depth soundings. Sea surface height variations are directly related to ocean floor gravity anomalies.

Science on a Sphere (SOS) (more info) A giant 6-foot diameter sphere uses projectors and computers to display scientific research of our globe. This site contains beautiful and informative videos of hundreds of datasets that have been displayed using the SOS system. Datasets include atmosphere, land, ocean, models, astronomy, and more. Geodedic animations include Sea Surface Height Anomaly

Marine Gravity from Satellite Altimetry (more info) This web site displays a global marine gravity map, produced from satellite altimetry, that has been sectioned into 16 clickable regions. A color poster of the map can be ordered for a fee.

Topography & Bathymetry

Global Relief Model Map (more info) Global Relief model combines land topography and ocean bathymetry to produce a beautiful and high-resolution map. Data include shoreline, bathymetry, topography, and bedrock all derived from hydrographic survey soundings, sonar bathymetry, satellite radar altimetry, airborne radar, and topographic maps. Web page contains extensive data as well as a Google Earth download (KMZ File 25kB Dec1 11) to display the map on a globe.

Deformation & Tectonics

A movie of the San Francisco area showing earthquake risk based on InSAR data . A very informative and interesting way of displaying geodetic data visually to understand a larger geologic problem.

Jules Verne Voyager, Jr (more info) Developed by UNAVCO, this interactive map tool provides a means to integrate base maps, and geographic and geophysical data. Velocity vectors can then be superimposed to create a visual representation of both 'absolute' plate motion and relative motion. Webpage gives background information and directions.

( This site may be offline. ) 3D tool to display and explore geodesy information. Data sets include Seismology, Geodynamics (GPS velocities, plate boundaries, the geoid, InSAR images, etc.), Geophysics, geologic maps and cross sections, and more.

University Navstar Consortium GPS Site Motion Vector/Crustal Velocity Archive (more info) UNAVCO GPS site motion vector archive. Includes project information, maps, links, data, and metadata from regional and global GPS analyses.

Hydrosphere and Cryosphere

Ocean Surface Topography from Space (more info) Interactive Flash Module about Ocean Surface Topography. Module includes sea surface observations and measurements as well as visuals explanations of the alimetry instruments used to detect surface changes.

GRACE: Tracking water from space (more info) This 7-minute video gives an overview of the GRACE (Gravity Recovery and Climate Experiment) satellites and explains the technique of using gravity to measure mass movement such changing as ice and snow. It gives examples of important things we have learned about climate change and water resources management from the GRACE mission. For example, snow & ice mass is depleting in places such as the Himalaya and ground water reservoirs are depleting in places such as Australia.
Sea Surface Height 1993-2011 (more info) Animation of the Pacific Ocean sea surface height from 1993-2011. Data gathered by multiple NASA satellite missions (TOPEX/Poseidon, Jason-1, and Jason 2). Animation shows view of Pacific Ocean and simultaneously graphs global average sea surface height data.
NOAA Near Real-Time Altimeter (more info) Interactive map interface displaying altimeter data globally (Sea Height Anomaly (SHA) and Significant Wave Height data). Select date/time/location to display. MAC USERS VIEW IN SAFARI.
The Real Time Ocean Environment (more info) Naval Research Laboratory shows regional map views of satellite derived ocean data. Data include altimetry, temperature and salinity, and more.
NASA Science Explorer (more info) Digital video globe that allows users to display dynamic digital images of the Earth, Sun, and other planets. User can turn the globe, display various data sets (carbon, water, climate, atmosphere, weather, etc) gathered from various satellite instruments. Information about the collecting instrument and the data set are displayed in a user-friendly interface. Touchscreen interface is available.

Public Applications & Handheld GPS

Geospatial Revolution (more info) Penn State assembled a public service media project about GPS and digital mapping. Episodes cover a variety of topics that pertain to the power of modern geospatial data, and the advent of handheld GPS units. Topics include: background history of geospatial information, Climate Change, war, natural disasters, refining business, interactive city, preventing hunger, and disease tracking.