[mkgmap-dev] Has anyone added a USA TIMEZONE overlay ontop of their custom maps?

Tue Jun 7 10:18:21 BST 2016

On Mon, Jun 06, 2016 at 01:09:34PM -0400, greg crago wrote:
>Since I cannot seem to get this feature added to the OSM database 
>(because it is not verifiable, or something) has anyone got this data 
>from a different source and combined to maps together so I can tell 
>when riding across the counrty thay I am crossing a timezone??

I would expect time zone to be an (explicit or implicit) attribute of a 
boundary=administrative relation. That is, the whole country or state 
(or province or city) would use the same time zone.

If the above does not apply (for example, if some US state is being 
divided by a time zone boundary), then some overlay of an external data 
source would indeed seem to be needed.

http://wiki.openstreetmap.org/wiki/Key:timezone seems to agree with my 
reasoning above. It also refers to a changeset that introduced time 
zones for the Australian states. However, all those modified objects 
have since then been removed, and the new Australian state relations do 
not seem to include timezone=*.

http://taginfo.openstreetmap.org/keys/timezone lists a number of values 
starting with America/*. Maybe the US states are already tagged?

There is also an algorithmic problem of extracting boundaries of tagged 
areas. Even if all the administrative areas are tagged with timezone=*, 
we would want to derive the boundaries, so that only those 
administrative boundaries that also represent a time zone boundary (with 
different values on each side) will be displayed.

Best regards,

	Marko