[OSM-talk] Projections

[Andy Robinson]

Christopher Schmidt
>Sent: 19 January 2007 3:58 PM
>To: SteveC
>Cc: Andrew Rowbottom; talk at openstreetmap.org
>Subject: Re: [OSM-talk] Projections
>
>On Fri, Jan 19, 2007 at 03:37:19PM +0000, SteveC wrote:
>> * @ 19/01/07 03:30:15 PM andrew.rowbottom at gmail.com wrote:
>> > >Are you trying to say that there is a standard for tiling in Mercator
>> > >projection written down somewhere, and we are breaking it?
>> >
>> > The big issue here is that the program used to display the tiles must
>> > know the projection used if it wants to convert pixel coordinates (or
>> > tile names) to lat/long. The current implementation assumes a
>> > particular conversion that is not the same for all the different sets
>> > of tiles.
>>
>> The current (top two layers) tiles can be dropped in to google maps -
>> it's a pretty compelling reason to stick with it.
>
>Unless you're using a different definition than I am, I don't think
>that's true... maybe I'm misunderstanding something though. Google, in
>my experience, uses a simple mercator projection, and OSM isn't creating
>tiles that match that...
>

Well this link seemed to spell out the Google code pretty well, so which
layer(s) does indeed use that math?

http://cfis.savagexi.com/articles/category/cartography

Cheers

Andy


Andy Robinson
Andy_J_Robinson at blueyonder.co.uk 


>Regards,
>--
>Christopher Schmidt
>MetaCarta
>
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