Spatial -

NOAA Datums Videos 2014

Differential correction with NA2011 and the newest epoch of NAD83

See our and Datums Basics and GPS Tutorials for the long-awaited results of months of rigorous testing and peer review

Trimble Positions software has replaced Trimble GPS Analyst in ArcGIS 10.1

ALASKA GPS and GIS users - check out Joel Cusick's Datum and Projections presentation Feb 2013

ArcGIS 10.1 - New and Cool improvements see Presentation from Melita Kennedy, ESRI : Projections and Datums Dec 2012

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Please help

Based on our findings here we hope you will help us spread the word and promote change by

·         Testing GPS data and stations in your own area

·         Occupying truth

·         Communicating those results with GIS/GPS community

·         Educating users on these issues


Test GPS data and stations in your own area

Our step-by-step, detailed methods are to incourage you to conduct your own tests. The latest projection (.prj) and transformation (.gtf) files are already installed in ArcGIS 10.1. Melita Kennedy, ESRI has made these files available for users not yet in ArcGIS 10.1 but desiring this functionality.   Likewise, this functionality is already installed in Pathfinder Office 5.3 but can be added to any version of PFO via this Pathfinder Office .csd file.

Occupy truth

In my demonstrations, locations were compared relative to each other.  I would be eager to see an updated OPUS 2011 position (today's standard) versus the same SSF with various processes.  This would allow these workflows to be analyzed for both accuracy and precision.

Communicate your results with GIS/GPS users, dealers and software companies

Datum shifts vary highly.  In tectonically active areas such as the Western US and AK, these datums shifts are significant.  This article has not addressed the latest NAD83 epochs for the Pacific NAD83(PA11) or Marianas Plates NAD83(MA11) but if a ticket shows up in my mailbox, I’ll be more than happy to come and do some testing on the beach or even AK if during the salmon runs!

Educate users of these issues

In his paper “Do the Right Thing, M Dennis, NGS notes  -

‘The software has also become easier to use, so that it is now possible for a user with minimal training to collect and process GPS data. Such “user-friendly” software has made GPS a much more accessible technology, yet this ease of use has come at a price: It is also easy for users with little geodetic knowledge to unwittingly generate erroneous coordinates.’