Þann 10.09.2016 18:47, Oleksiy Muzalyev reit:
On 10/09/16 20:23, Colin Smale wrote:
On 2016-09-10 18:55, Oleksiy Muzalyev wrote:
Latitude and longitude are physical values, they will never change
for a house on Earth, no matter what. They do not depend on
politics, economics, linguistics of the current moment.
You sure about that? Plate tectonics means that everything is in
motion, albeit slowly. On top of that there have been a couple of
"adjustments" to WGS84 which have caused coordinates to change.
Hello and welcome to the wonderful world of plate tectonics.
Iceland has its own co-ordinate system ISN and makes an updated version
every decade. We still use ISN93 mostly but we also have a ISN2004 and
the difference there was between 7 cm and 23 cm from the previous
decade. Iceland is slowly migrating not only north but the western part
is going west and the eastern part is going more east with the southern
part starting to lag behind in movement and a few points there starting
to migrate more south.
Work is ongoing on ISN2016 measurements.
http://www.euref.eu/symposia/2015Leipzig/06-12-Iceland.pdf
This is also why we are not always overly fastidious in making a
millimeter accurate feature on OpenStreetMap because it is gonna shift
anyways.
--
Jói
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