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Precise Geodetic Infrastructure: National Requirements for a Shared Resource
FIGURE S.1 The geodetic infrastructure supports many research and practical applications. For example, this infrastructure is critical to measuring: (A) Major groundwater depletion in India. (B) Uplift of the crust near the Three Sisters volcanoes, Oregon. (C) A landslide near Flathead Lake, Montana, revealed through the obscuring tree coverage using airborne LiDAR data collected by the NSF National Center for Airborne Laser Mapping (NCALM). These and other examples, as well as figure credits, are presented in Chapter 3.
all observing systems and applications over time; its main function is to provide the necessary information, such as the International Terrestrial Reference Frame (ITRF),2 that underpins many Earth observation missions and location-based applications. The strength of the infrastructure lies in its
The International Terrestrial Reference Frame (ITRF) is a consistent set of agreed-upon 3-dimensional time-dependent coordinates for a network of reference points, distributed globally, which in turn are used to define the locations of all other sites. The DoD World Geodetic System 1984 (known as WGS-84) is consistent with the ITRF at the few-centimeter level, but the latter is intended for applications requiring the highest geodetic precision.