I'm in the process of creating a webpage to ease the process of visualizing NOTAM navigation warnings. Never done any geospatial software development before, so all the terms like geoid, reference ellipsoid, datums, different coordinate systems are new to me, though I've been doing a lot of reading up on the related material. I'm using the DotSpatial.Projections library to load the projection info either based on the EPSG code or the corresponding proj4 string. The target coordinate system is the one used by Google Maps API - (WGS84 / EPSG 3857).
I'm having trouble figuring out the proper conversion source coordinate system/projection. What I've come up with does not give the proper results: https://epsg.io/transform#s_srs=42310&t_srs=4326
The source coordinate system is described here: http://eaip.eans.ee/2018-02-01/html/eAIP/EE-GEN-2.1-en-GB.html#GEN-2.1-Geodetic
The converted nor the original coordinates don't align with the expected result. For example, the Zone 9 near north of Estonia surrounding Tallinn: Expected result, actual result on my website (large red/green polygon south of Tallinn)
Some proj4 strings I've come up with: NOTAM:
+proj=lcc +lon_0=24.0 +lat_0=57.51755393 +lat_1=58.0 +lat_2=59.3333333 +ellps=GRS80 +datum=WGS84 +units=degrees +no_defs
+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs
The aforementioned two strings result in a very tiny projection near the reference point of the source coordinate system.
This application is initially for personal use as a drone pilot to visualize if there are any flight restriction zones active at a given time.