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CLSA Webinar: Demystifying Reference Frames and 3D Datums - Greg Helmer


Mr. Helmer is a Professional Land Surveyor registered in California, Colorado, Arizona and Nevada with over thirty-five years of experience in geodetic control, Surveying Geomatics and GIS. He is Vice President and Team Leader of geospatial services at Psomas. Mr. Helmer has published dozens of articles and professional papers and is nationally recognized for his contributions to GNSS surveying and high-precision geodesy. Mr. Helmer is a graduate of Chapman University, a contributing author to the National Height Modernization Program for NOAA, a Fellow in the Institute for the Advancement of Engineering, a Fellow with the American Association for Geodetic Surveying, and a founding member and past Chairperson of the California Spatial Reference Center at Scripps Institution of Oceanography.

Demystifying Reference Frames and 3D Datums

If my Quad Map is in NAD27 and my GIS land base is in NAD83, my local control network is in the 2011.00 epoch and the satellite orbits are in WGS84… or maybe it’s ITRF14 or 08… oh, I’m so confused. And then there’s elevations. If I’m using Geoid12B with NAVD88, and I need to know local MLLW, do I need to stand on my head and drink from a tide gauge to face up?

It’s no wonder that really-smart people are so confused. And it’s going to get worse. The proposed modernization of the National Spatial Reference System in 2022 promises to bring coordinates and elevations into closer alignment with GNSS orbits, and to introduce an additional transformation parameter in the form of a Euler pole and rotational velocity. Stay tuned. This webinar attempts to walk through the concepts of basic geodesy from plane coordinates, to earth-centered-earth-fixed cartesian coordinates, to spherical coordinates in inertial space, and 14-parameter transformation models; and yes, Euler poles, as well as gridded velocity models. If your head is not spinning by then, we will touch briefly on geopotential heights.


Earlier Event: June 30
OC-CLSA Angels' Night - June 30, 2017
Later Event: July 28
Pool Tourney & Board Meeting