Presentation on theme: "New Geometric Datum: plans Modernizing the U.S. National Spatial Reference System FGCS San Diego, California Monday 11 July 2011."— Presentation transcript:
New Geometric Datum: plans Joe.Evjen@noaa.gov Modernizing the U.S. National Spatial Reference System FGCS San Diego, California Monday 11 July 2011
Geodetic control is the foundation for all geospatial products. Geodetic Control is the critical “basemap” layer for GIS applications Coordination begins with good coordinates Source: Zurich-American Insurance Group
Crustal velocities Passive networks are aging ( instability, accessibility, loss) How accurate is the NSRS?
stable N.A. world avg. NAD83 vs GNSS 2.2 meters NAD 83 Origin Earth’s Surface ITRF Origin ( Identically shaped ellipsoids )
New geometric datum minus NAD 83 (horizontal)
New geometric datum minus NAD 83 (ellipsoid height)
1.6 meter shift on a 1:25,000 map modern users abuse map scale NAD83 and GNSS lat/lon lattices are 0.006 cm apart Accurate and seamless!! Optimized for my project!!
the path to a new geospatial datum SCIENCE: – participate in international geodesy – maintain core geodetic infrastructure – define stable North America, plate motions, local issues OUTREACH: – illustrate limitations of current system – geospatial summits with FGCS, ACSM, ION, etc. – assist key stakeholders to identify use cases, issues TOOLS: – dependable models – GEOID, NADCON, H(+V) TDP exploitable via vendor toolkits – services for RTN operators
the path to a new geospatial datum DEFINE: – Fixed to plate at what epoch? Update frequency/tolerance? – Coordination with international community, Canada, Mexico, etc. – FGDC vote to adopt, Federal Register Notice, formal report, & FAQ IMPLEMENT: – Products (datasheets, OPUS, GEOIDs, maps, charts, projects) – Toolkit (NADCON, TDP) and best practices – Legacy plan: how much support for USSD, NAD27, NAD83 TIME FRAME: – Follow in synch with geopotential datum effort – Note, NAD27 is still in use.
Benefits, Progress… and Challenges o Benefits o Facilitates direct use of GNSS for positions and “physical” height determination o More closely aligned with CORS and global reference frames (e.g., ITRF) o More efficient, less reliance on passive control o Better monitoring/modeling of temporal change in coordinates, heights, and gravity o Progress o Multi-Year CORS Solution and new adjustment of passive GNSS control o Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project underway o Federal geospatial summits to communicate change to users (2010, 2012, more in future) o Challenges o Coordination with neighbors (Canada and Mexico) o Fix new geometric datum to North American plate? o Integration of GNSS heights (using geoid model) w/geodetic leveling; Dynamic heights o Providing means/best practices for users to move data to new datums o Depends on full funding for GRAV-D (and schedule) o Original completion target 2018, now by 2022…
Geospatial summit 2012 What do you want to talk about? geodesy.noaa.gov/2010Summit/ Presentations Handouts Proceedings
Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey Replacing NAD 83 Want the new reference system to be more geocentric Option 1: Adopt ITRF20xx Option 2: Adopt reference frame that agrees with ITRF20xx at some instant of time, but does not move relative to “stable” North America.
Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey Option 1: Adopting ITRF20xx Advantage: Ideally there would be just one reference frame for everyone in the world. (Note: The current WGS84 realization is essentially equivalent to ITRF2000 and its next realization will be essentially equivalent to ITRF2008.) Disadvantage: All points in North America would have significant horizontal velocities –In central & eastern CONUS, between 1 and 2 cm/yr –In California, western Oregon, western Washington, Alaska and Canada, more than 2 cm/yr
Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey Option 2: Frame fixed to North American plate Advantage: Points in “stable” North America would experience no significant horizontal motion. Disadvantage: Each tectonic plate would need its own reference frame. Hawaii is located on the Pacific plate, Puerto Rico on the Caribbean plate, and Guam on the Mariana plate. Also, points located near plate boundaries would still be moving significantly (eg., California, Oregon, Washington, southern Alaska).
16% of US population lives in the Pacific region.
Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey Analogy with time systems The world has adopted essentially two time systems: * Universal Coordinated Time (UTC) for global applications * Local time for applications within a single “time zone” The conversion between the two time systems is simply a matter of adding or subtracting an integral number of hours.
Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey Can the geospatial community deal with two geometric reference systems? ITRF20xx for interplate applications Plate-specific reference frames for intraplate applications A conversion between two given frames would simply involve applying a set of 3 rotation rates.
Positioning America for the Future NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION National Ocean Service National Geodetic Survey EPOCH DATE … date for which published positional coordinates are valid.
National Spatial Reference System (NSRS) The NSRS is a consistent coordinate system that defines latitude, longitude, height, scale, gravity, and orientation throughout the United States. Evolving from passive to active to real-time augmentations One common datum for all FGDC products (yours too?) Geodetic control: overview & evolution