Hermosillo timezone

[Rui Lopes]

Eric Muller wrote:
> Jesper Norgaard Welen wrote:
>> Of course you would need the Latitude and Longitude of the airport codes
>> to do what *you* mentioned, but I assume that would be trivial?
>>   
>
> The UN/LOCODE (CODE FOR TRADE AND TRANSPORT LOCATIONS) database has 
> coordinates for many locations, and airport codes for airports. 
> http://www.unece.org/cefact/locode

I've tried to use the geonames.org database, but some airports seem to 
have wrong coordinates (when seen in google maps). I'll try to compare 
it with LOCODE db.


> Generating the list for all the airports should be relatively trivial 
> if you put the map in spatially-enabled database such as PostGIS. 
> Something like
>
> SELECT unlocode.code, tz.tzid
> FROM unlocode, tz
> WHERE ST_within (tz.geom, unlocode.location)
> AND unlocode.class = airport;
>
> assuming that unlocode is a table  for the UN/LOCODE database and the 
> coordinates have been turned into point geometries (of course, the SQL 
> above is just the idea)

the tz table is from your shapefile at http://efele.net/maps/tz/world/ ?


> The main difficulty would be to have a good enough map, so that the 
> UN/LOCODE coordinates do not fall in water. May be a bit of buffering 
> around the point and an intersection with tz polygons would do the trick.

By map you mean the TZ map from your shapefile?

Can you elaborate a bit about the buffering and intersection?   (I'm 
starting to enter into the GIS world, so I don't yet known the lingo).

Thanks.

Best regards,
Rui Lopes