University of Wisconsin–Madison

Wisconsin Geospatial News

Fun with Geodesy

Last week I attended a “geodesy refresher” course offered at the Wisconsin Society of Land Surveyors Annual Institute in the Dells.  Dave Doyle, former Chief Geodetic Surveyor with the National Geodetic Survey (NGS), was the instructor for the day-long training session.

We all groan and our brains hurt just a little when we start to think about datums, transformations, and geodesy in general, but Dave definitely has a knack for making those topics both interesting and entertaining.  Dave had a long and distinguished career with NGS before retiring several years ago. He continues to work in the field of geodesy, offering consulting services through his company.

I can’t begin to summarize the depth and breadth of knowledge Dave shared last week, but happily, you can get the same info directly from him in a series of YouTube videos produced by the Florida Surveying and Mapping Society in 2016.

Dave talked a lot about an upcoming datum change happening in 2022.  Suffice it to say, this is something we all need to pay attention to.  Unlike recent datum adjustments where some users could perhaps ignore small positional differences (right or wrong), the 2022 change will be significant enough that all users will need to take note.  The changes will not be as significant as the move from NAD 27 to NAD 83, but they are noteworthy none the less.

I don’t want to quote too many numbers from Dave’s presentation last week since I have many numbers swimming around in my head, but I recall a positional shift of about 1.3 meters is expected in most parts of Wisconsin. The sixth video in Dave’s series addresses the 2022 datum in detail.

Check out Dave’s videos, a little extra knowledge never hurts.