[a little bit OT] calculating X,Y from latitude and longitude

[Kobben, Barend (UT-ITC)]

You can’t unless you know which X & Y you want/mean. It is NOT correct to say that y is latitude and x is longitude!! XY means you use a cartesian coordinate system (the map = flat rectangle) instead of lat & lon which are angles from the center of a spheroid or ellipsoid (the globe = a 3D object).

We call the transformation from 3D globe to flat map a projection. There are endless ways of projecting. Choose one of those projections and do the math and then you go from lat-lons to y-es and x-es...
For a nice overview of all this see e.g. https://kartoweb.itc.nl/geometrics

Yours,
--
Barend Köbben
Senior Lecturer/Researcher – ITC-GIP
Thesis Coordinator STAMP & M-CARTO (Joined Erasmus Mundus MSc in Cartography)
University Twente, PO Box 217, 7500 AE Enschede (The Netherlands)
+31-(0)53 4874 253 / room 1303 Langezijds (Hallenweg 8)

On 18/08/2025, 21:53, "Luca Bertoncello" <lucabert at lucabert.de> wrote:

Am 18.08.2025 um 17:34 schrieb Robert Hewlett:
> First step, make sure you are not crossing over.
>
> You say x y but latitude longitude is y x.

Yes, I know... y is latitude and x is longitude...
How can I calculate them?

Thanks
Luca Bertoncello
(lucabert at lucabert.de)
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