I find this thread interesting. In my experience overlaying both raster (orthophoto) and vector data in Google Earth with KML, EPSG:4326 has worked with no problems whatsoever. So far as I know, GE does not apply a vertical datum, it simply drapes the 2D data over its internal terrain model.
Would it be possible for you to share some data where you have seen that this is a problem? Thanks, Roger On Fri, Oct 28, 2011 at 1:05 PM, Hamish <[email protected]> wrote: > Helmut wrote: > > ... > > > in my experience overlaying kml (vector and raster) > > > with EPSG:4326 in google > > > earth works relatively well in flat areas, in mountain > > > areas there are > > > sometime distortions therefore. > Markus: > > I can confirm this from my (limited) experience to export > > data to KML. To correct for the geoid heights, you could use > > the previously indicated map and calculate the local > > ellipsoid-geoid difference and vertically shift your vector > > data with v.transform. > > Then export to KML. For raster, use r.mapcalc to shift. > > n.b., IIUC raster KML support in google earth is essentially a > hack building on/abusing their raster-icon support. > they may have improved things, but this is what I was lead to > believe at the time of writing r.out.kml. > > probably it is useful to consider if the ellipsoid-geoid > difference is important vs. the overall vertical differences > in the data, if the result is just for viewing maybe it is not > worth the trouble. > > > Hamish > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user >
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