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Hello I want to create an overlay for google maps. As far as I know google maps using Spherical Mercator, so the system where I read the maps use Mercator but is not specified which (spherical or cylinder) type it use.

When i create the images, i get some information in common. That means I have an offset. I want to try to solve this using cylinder mercator coordinates, but i don't know how can i transform google coordinates to Cylinder Mercator coordinates.

Thank you in advance.

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I suppose you mean Spherical vs Elliposidal Mercator. Google use real WGS84 coordinates and map them as if they were on a sphere rather then an ellipsoidal datum. It depend on the coordinates of your original images how to reproject them on Spherical Mercator projection. You can user gdal_transform or whatelse GIS tool to do the transformation. The target CRS is EPSG:3857 (or the legacy, not standard, EPSG:900913).

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