[Fwd: [Proj] Re: Problem overlaying georeferenced images in Google,
jorge.arevalo at gmail.com
Wed Jun 4 09:15:31 EDT 2008
> The Mercator-based coordinate system used by Google Maps can be
thought of in
> two ways.
> 1) It uses a sphere with radius=6378137.0 m. Sent to Mercator, hopefully, the
> code is smart enough to use the spherical equations.
> 2) It uses WGS84 with spherical Mercator equations.
> No ellipsoid-to-sphere conversion should take place. Data that's really on WGS84
> is assumed to be on the major auxiliary sphere (R=6378137.0m) and just projected
> using the spherical math. This means that you can't create a custom 3 or 7
> parameter datum transformation to convert directly to the sphere (because the
> latitude values are converted to the sphere).
> So you might try transforming your data from ED50 (or other datum) to WSG84
> first. Then project those coords to the Google Mercator.
> ESRI, Inc.
I forget it...
Really, what I put over the GMaps' frame isn't an only image. Really, I put many images of 100x100 pixels
(based on the raster) together. And after putting them, I "move" to avoid the overlap, as you can see
in this screenshot
I thought that I could avoid the overlap by reprojecting the raster, obtained from a MIF/MID files with UTM
projection and ED50 datum, of course, but I'm not sure now...
Anyway, thanks a lot everyone!
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