[Proj] Problem overlaying georeferenced images in Google, Maps(projection problem!)

[support.mn at elisanet.fi]

Hmmm....

are you sure the "gdalwarp" you are using uses the latest proj-4 libraries?
Are you sure all programs are doing what thye should? If so, it is maybe the
input data (assumptions) then?

Regards: Janne

------------------------------ 

Jorge <jorge.arevalo at gmail.com> kirjoitti: 
> Now, the results in Google Earth:
> 
> The image before reproyecting (UTM zone 30 datum ED50)
> http://www.nebulared.com/tmp_geo/Balearic_Island_UTM_ED50.png
> 
> The image reproyected
> http://www.nebulared.com/tmp_geo/Balearic_Island_Reprojected.png
> 
> What's the problem?:
> - The input image's projection really isn't UTM ED50 (Mapinfo lies??), or is bad georeferenced (low probability...)
> - The output image's projection really isn't GMaps projection (assuming GMaps projection = GEarth projection)
> - GMaps projection not equal GEarth projection (I think so...)
> - Any other?
> 
> The line executed:
> gdalwarp 
> 	-s_srs "+init=epsg:23030 +towgs84=-84,-107,-120,0,0,0,0" 
> 	-t_srs "+init=epsg:3785 +towgs84=0,0,0,0,0,0,0" 
> 	-tr 250 250 
> 	-co INTERLEAVE=PIXEL 
> 	Balearic_Island_UTM_ED50.png
> 	Balearic_Island_Reprojected.png
> 
> The epsg codes:
> Input code (23030):
> # ED50 / UTM zone 30N
> <23030> +proj=utm +zone=30 +ellps=intl +units=m +no_defs  <>
> 
> 
> Output code (3785):
> # Spherical/Web Mercator
> <3785> +proj=merc +lat_ts=0.0 +lon_0=0.0 +k=1.0 +x_0=0.0 +y_0=0.0 +a=6378137.0 +b=6378137.0 +units=m +nadgrids=@null +no_defs <>
> 
> 
> Sorry for the insistence, and thanks a lot
> Jorge
> 
> Jorge wrote:
> > The EPSG code 3785 is a custom one, but the same of 900913 (I didn't know it thanks), except for the "+wktext" term. What does it mean?
> > 
> > OK, I'm lost with this issue. Could my calcs be wrong? I have, for example, this image:
> > http://www.nebulared.com/tmp_geo/UTM_ED50_Balearic_Island.png
> >
> > And is georeferenced by this world file:
> > http://www.nebulared.com/tmp_geo/UTM_ED50_Balearic_Island.wld
> >
> > The image is obtained for a MIF/MID couple of files with UTM projection, zone 30, ED50 datum (Mapinfo said... I don't know what 
> > are the dX, dY, dZ parameters, buth they must be -84, -107, -120). Really, the raster file obtained from MIF/MID files isn't a
> > PNG file, but I did the transform to "see" what I was doing.
> > 
> > OK, I need to reproject the image, and the output image must be used to overlay it in a GMaps' frame. This is my last attempt:
> >
> > gdalwarp 
> >	-s_srs "+init=epsg:23030 +towgs84=-84,-107,-120,0,0,0,0" 
> >	-t_srs "+init=epsg:3785 +towgs84=0,0,0,0,0,0,0" 
> >	-tr 250 250 
> >	-co INTERLEAVE=PIXEL 
> >	UTM_ED50_Balearic_Island.png
> >	GMaps_Balearic_Island.tif
> >
> > Then, I transform the TIFF file in a PNG (transformation OK) and I have this image:
> > http://www.nebulared.com/tmp_geo/GMaps_Balearic_Island.png
> >
> > But the image doesn't fit exactly in the map... Is there any error in this reprojection? If the projection is OK, I need to review
> > the rest of the code...
> 
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