Rotate map while rendering

[hholzgra]

I am still looking for a way to render a rotated map, so that the top of it is not oriented to true North, but towards the direction a person facing the map would be looking, like e.g. those tourist guide posts in London:

https://www.alamy.com/stock-photo-london-england-uk-you-are-here-tourist-map-in-trafalgar-square-nelsons-118350972.html?imageid=0A9DD1D6-04EB-405B-A2EB-2231B40BCB62

I am aware of earlier issue #531, but none of the projection tips given there ever worked out for me, and doing coordinate transformation on database import already is also not an option as I'd need this for an on-demand service with a full planed database behind it.

The original patch mentioned on issue #531 unfortunately seems to have been in the original Trac instance, and is now lost forever? I remember having tried to contact the original author back in 2016, but never noticed any reply, and the Trac mirror instance then still available did not seem to have the attachments, only the message texts.

Issue #531 was closed as "completed" in 2015, but without any comment ... :(

[cadnant]

A couple of different options that use Mapnik as-is, both based on experience with magnetic-north aligned or arbitrarily aligned maps at https://github.com/oobrien/oomap

1. Query a larger true-N aligned bbox and render to a rotated canvas;
2. For PostGis queries, wrap the geometry column SELECT statement in an ST_ROTATE() function.