Proj is like that: it goes wrong silently. I have had a quick look at the question of proj data files. There is a package called proj-data which contains all the data files that proj might look for. There is information on Docker https://hub.docker.com/r/osgeo/proj/ and on the proj website https://proj.org/en/stable/install.html . Also, if it configured correctly, proj should automatically download any data file which it looks for, but isn't in the data files folder.
I am encouraging you to use ETRS89 coords *because it will fit best with what OSM is doing in GB*. The OS has always worked with coordinates fixed to the land. They do all their surveying with GNSS receivers using RTK, and they work in ETRS89. Then they pass almost all of their data through the lens of National Grid (using OSTN15) before making it available. Thereby they cause a lot of confusion. The archive data you are working with was obtained by classical surveying methods: triangulation and levelling, using optical instruments (theodolites). The coordinates are inherently fixed to the land because the triangulation pillars are fixed to the land. So the date does not come into it; the measurement would have been the same whenever they did it. And most of the surveying was done before the idea of plate tectonics was accepted. On the other hand, the WGS84/ITRS coords of a given landmark are constantly changing. So if you convert to WGS84/ITRS you will be obliged to choose the date for which the conversion will be done. I guess most people would choose the date on which they did the conversion. Perhaps the different iterations (e.g. WGS84 G1762, ITRF2020) come with default dates if you don't choose one (or if the software doesn't let you choose). If you want to see what the difference is between ETRF and ITRF coords, there is a conversion tool on the EUREF website https://epncb.oma.be/_productsservices/coord_trans/ . This tool allows you to choose the date for which the conversion will be done. But understanding this tool, is hard. It really is specialist stuff. I think it would be a good idea for our colleagues in the USA to choose a specific date for their conversions to WGS84. This is so that different users' contributions will match up. Perhaps they have chosen a date by default, by recommending to convert to WGS84 G2139. This is on https://wiki.openstreetmap.org/wiki/How_to_transform_data_from_NAD83_to_WGS84 . _______________________________________________ Talk-GB mailing list [email protected] https://lists.openstreetmap.org/listinfo/talk-gb
