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I run gdal2tiles.py on a vrt (EPSG:4326) file and gives good results when overlay over OSM. Openlayers projection is EPSG:900913. The output is a set of directory/files (z/x/y). I used ms4w.

However, when I use slippy map calculations to find x/y tiles using equations here (lon/lat to tile numbers) it gives wrong y tiles (14730 in equations 17876 in gdal2tiles) (x tiles are the same as gdal2tiles).

When I reverse sign y coordinates I get right tile numbers, but the reverse equation (tile number to lat/lon) gives negative lat coordinates.

Is this related to coordinates transformation?

Thanks.

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Can you expand this a bit more, to show the calculations you are trying to do and the working in your working of the equations? – BradHards Aug 19 '12 at 11:32

closed as too localized by underdark♦ Aug 20 '12 at 6:35

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1 Answer

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Sorry, The above calculations on both methods are correct. The thing that made this confusion is that gdal2tiles calculated tile set per mercator profile (default) even the vrt file is EPSG:4326, while I was calculating mine on geodetic profile. When I set the profile to geodetic I got same results.

Note: tile set for geodetic/mercator is different, although x coordinates are the same.

Regards,

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