Hi Andrew. Thanks for taking the time to read my email and reply it. I'm aware of Copernicus land and other datasets like SMRT3 and ASTER however I need the best possible elevation resolution available. To do so, I'm getting the elevation dataset directly from countries geographic institutes and converting them into the coordinate system 4326+3855. But as described in my previous email, I'm having some trouble with some geoids. Do you have an idea why I'm having these transformation issues? To be honest, I'm a bit lost because I can't understand it.
Thanks again for your help, Diogo On Fri, 14 Oct 2022 at 15:57, Andrew C Aitchison <and...@aitchison.me.uk> wrote: > On Fri, 14 Oct 2022, Diogo wrote: > > > Hello everyone! > > > > I'm merging multiple elevation datasets from different countries and I > > would like to re-project all into the same coordinates system, 4326+3855 > > using gdalwarp. I'm using `gdaltransform` to confirm that there is in > fact > > a conversion from the original projection to the aspected one. However, > for > > some datasets, there is only conversion in the XY axis, while the Z > output > > is the same as the input. > > Is there a good reason to start with these particular datasets ? > > There are international bodies who have produced elevation datasets > covering the whole of > Europe, eg > https://land.copernicus.eu/user-corner/how-to-access-our-data > > https://www.eea.europa.eu/data-and-maps/data#c0=5&c11=&c5=all&b_start=0&c12=elevation > > https://www.eea.europa.eu/data-and-maps/data/copernicus-land-monitoring-service-eu-dem > > which would save you trying to stitch together data in different CRSes. > > > Below there are some examples (the geoid code is extracted from the > dataset > > documentation) > > > > Genoa 1942 height (Italy) > > > > $ echo "14.995 37.755 3357" | PROJ_NETWORK=ON gdaltransform --debug on > > -s_srs "EPSG:4326+3855" -t_srs "EPSG:32632+5214">> 1028333.73796622 > > 4195591.29690422 3357 > > > > N2000 (Finland) > > > > $ echo "25.15296 62.50195 269" | PROJ_NETWORK=ON gdaltransform --debug > > on -s_srs "EPSG:4326+3855" -t_srs "EPSG:3067+3900">> 404861.868388335 > > 6931460.32557422 269 > > > > EVRF2007 (Estonia) > > > > $ echo "27.059167 57.714444 318" | PROJ_NETWORK=ON gdaltransform > > --debug on -s_srs "EPSG:4326+3855" -t_srs "EPSG:3301+5621">> > > 682284.606829111 6401087.4159131 318 > > > > > > I don't have much experience with the projections and I'm a bit lost > > to understand the possible issues, or interpreted the Z output. What > > can be the possible issues? > > > > Any help would be appreciated. > > > > Best regards, > > > > Diogo > > > > -- > Andrew C. Aitchison Kendal, UK > and...@aitchison.me.uk >
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