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0 pointsbee_rider2y ago0 comments

Hi from New England, middle-of-the-plate buddy. In fact, it had never occurred to me that the mapping of parts of the ground to, like, latitude-longitude could be time dependent, haha. I guess this could make a big difference in surveying.

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manarth2y ago

Latitude-Longitude are references within a CRS (Coordinate Reference System).

US mapping can be based on USNG (United States National Grid) which is a cartesian geometry reference system, and if the entire USA moved a meter to the east, you may find that your USNG coordinates do not change at all.

The most common CRS is called WGS84, as this is the reference CRS for GPS. If the USA moved a meter to the east, the WGS84 coordinates would change.

There's a field of study devoted to translations between different coordinate reference systems, projections, geometries and more – and that's before we even get to mapping Mars or the Moon!

Geospatial definitions have a similar delight to date definitions, in that any and every reference could be annotated with "It depends" :-)

blacksmith_tb2y ago

For most surveying wouldn't the the relative, nearby points be shifting together equally?

johncalvinyoung2y ago

not in California, Iceland, or Japan!

midasuni2y ago

It’s unlikely the relative position of Griffiths Observatory and the Chinese Theatre would change though, both may shift north by 74cm relative to Las Vegas sure, but I’m not aware of any faults between those two points

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