Add Finnish geoid models

[jjimenezshaw]

Three geoid models for Finland based on these three transformations in EPSG

https://epsg.org/transformation_10694/EUREF-FIN-to-EUREF-FIN-N60-height-1.html
https://www.maanmittauslaitos.fi/kartat-ja-paikkatieto/asiantuntevalle-kayttajalle/koordinaattimuunnokset/fin2000-geoidimalli

https://epsg.org/transformation_10696/EUREF-FIN-to-EUREF-FIN-N2000-height-1.html
https://www.maanmittauslaitos.fi/kartat-ja-paikkatieto/asiantuntevalle-kayttajalle/koordinaattimuunnokset/fin2005n00-geoidimalli

https://epsg.org/transformation_10698/EUREF-FIN-to-EUREF-FIN-N2000-height-2.html
https://www.maanmittauslaitos.fi/en/maps-and-spatial-data/coordinates-and-positioning/koordinaattimuunnokset/fin2023n2000-geoidimalli

[jjimenezshaw]

@phakli , @jratike80

[rouault]

[jjimenezshaw]

@jratike80 (coming from another PR, but talking about this PR)

Hi,

I checked the TIFF files with gdalinfo. Pixel sizes, extents, and metadata tags look good to me. I believe that MMT here means MML (MaanMittausLaitos). MMT refers usually to Doctor of Agriculture and Forestry. But maybe MML would not add any value, while the full name National Land Survey of Finland might do that.

TIFFTAG_COPYRIGHT=Derived from work by NLS (MMT) Finland. CC-BY-4.0 https://creativecommons.org/licenses/by/4.0/

I changed it in the README and Metadata

[phakli]

Thanks @jjimenezshaw. I checked the grid files against the test data and they produce expected results. So all good from our side.