Tag Archive: datums

Jan 14 2013

A Few Good Reads (1/14/13): The 2012 Disaster Tally and Underestimating the Elwha Dam Removal

This week: Hurricane Sandy tops the 2012 disaster list, the silt total underestimated at Elwha Dam, the Morganza levee project swells in cost, using biomimicry to protect coastal cities, and the decaying thousands of bridges in America . Hurricane Sandy Tops 2012 Disasters, But More in Store for 2013 (Property Casualty 360) Flood losses are …

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Jun 02 2011

The Vertical Side of Things

A vertical datum is defined by the measured gravity anomalies between ellipsoid and geoid. But it’s not quite that simple. Between understanding mean low water versus mean high water versus mean low low water versus mean sea level, this area can get very dangerous. On top of that you have other things to complicate the …

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May 31 2011

Rescue Your Floating Data

UTM

We’ve previously discussed some of the basics of geodesy, ellipsoids and the geoid,  as well as datums and projections. Now, it’s time to pull it all together into what a coordinate system is. Knowing about coordinate systems matters because this is what you interact with inside of a GIS or even CADD currently. Your project …

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May 17 2011

Where am I?

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“It is clear that the earth does not move, and that it does not lie elsewhere than at the center.”                 – Aristotle (one of first to estimate size of the earth, On the Heavens, p54) We’ve talked a little about geodesy and reference ellipsoids but what is a datum? It’s pretty simple, actually. A datum …

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