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I wonder if I can do simple arithmetics with coordinates. Can I do substraction of coordinates like 2.570801 (lng) 46.89023 (lat) / 17.424316 (lng) 55.15377 (lat)?! Or will that get messy without a CRS?!

four-eyes
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  • Welcome to GIS SE! As a new user be sure to take the [Tour]. – PolyGeo Aug 25 '15 at 10:46
  • Short answer: No. Long answer: Search on "geodetic". BTW, it's not messy "without a CRS", it's impossible. It's a CRS with a GCS that makes it messy (partial differential equation). – Vince Aug 25 '15 at 10:48
  • @Vince thanks. It felt queer to do calculations but I did not know what to search for! – four-eyes Aug 25 '15 at 11:28
  • why do you want to do the substraction ? sometimes you could be just fine with simple arithmetics but you need to understand what you are doing. Sometimes it can get terribly wrong if you handle an angular coordinate like a cartesian one. – radouxju Aug 25 '15 at 13:33

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Yes, you can do that. You might want to look into spherical trigonometry for that. Though i personally find it much harder to interpret the results this way and would project the data into a metric-based crs like utm before doing any arithmetics.

karpfen
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  • Thanks! Meaning, I cannot calculate with the values I have there - I need to transform them? Would it work with degrees? – four-eyes Aug 25 '15 at 10:45