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I have a database with coordinates in WGS84 (4326) that all of them belong to Italy. Italy is split in two more or less equal UTM zones, 32 and 33. I need to transform those geographic coordinates to a projected system, but I don't want them to be in two different systems (ETRS89 UTM 32N AND ETRS89 UTM 33N), I want to keep them in a single representative SRID. My guess is that I should stick to something based on ETRS89.

I have the same problem with Mexico, which has several official UTM zones and I need to represent coordinates in just one. After a lot of searching, I found ITRF2008 LCC, but I don't know if that should be the one to go with.

So what should be the projected system to use for point representation and distance calculation for the whole country of Italy and Mexico? Is there a method to make this kind of decisions when you run into an area with several equal UTM zones? Is there a consensus about this?

It is clear that when a country has most of its area in a single UTM zone (like Spain), you just pick the one that covers the biggest area like asked here. What about these two countries?

Also, this is for professional use, so the chosen system should be something somewhat "official" or "standard" if possible.

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    UTM, by its very nature, represents a six degree slice of the globe. While it is possible to map outside the three degrees outside the central meridian, significant error is introduced outside of six degrees. Every country has a standard projection used for mapping. Wide countries are likely to use an Albers Equal Area or similar comic projection. Determining which projection(s) is(are) standard for which country is a lookup task, which varies by GIS package (and country). – Vince Apr 10 at 10:49
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Some countries have never published a countrywide projected coordinate reference system (CRS). The only way to discover it if no one contacts a GIS software vendor or CRS registry is if it's easily found on the national mapping agency's website or you start checking metadata information.

According to the EPSG registry, there is one for Italy based on RDN2008:

7794: RDN2008 / Italy zone (E-N)
6785: RDN2008 / Italy zone (N-E)

The only difference is in the axis ordering--easting-northing or northing-easting when interchanging or displaying the data. The N-E zone was added in 2014 while the E-N one was added in 2016, so relatively recently. They use transverse Mercator, so a wide zone and conformal which maintains shape/angles, not areas.

As you've found, the only widely (relatively) known countrywide projected CRS for Mexico is the ITRF2008 Lambert conformal conic one.

If you're doing statistical analysis, it's often better to use an equal area projection instead like Albers or Lambert azimuthal equal area. If there's nothing available, placing the standard parallels of Albers at approximately 1/6th and 5/6th of the north-south extent is a typical setting to use.

  • Thank you for the info, I will check out that italian CRS. Thank you very much! – A.T. Apr 11 at 6:11

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