Support for non Web Mercator (EPSG 3857) tiles.

[LebronsDad]

Does Terracotta support serving non Web Mercator tiles?

I tried to change _TARGET_CRS: str = "epsg:3857" and target_crs: str = "epsg:3857", to use "epsg:4326" for the Equirectangular projection. It doesn't throw an error, but I'm getting blank map tiles. Am I doing something wrong or was Terracotta not meant to be used this way?

It would also be nice to have a setting to easily change this in the config.py

[dionhaefner]

That does not work because there is no mapping from physical bounds to xyz tiles in that case. We are using mercantile for this conversion which is specifically tailored to Web Mercator.

There may be conventions on how to define xyz tiles for other CRS; in that case, the functions in terracotta.xyz would have to be re-implemented to reflect that. Happy to review a pull request if anyone wants to contribute that functionality.

[j08lue]

There is a library for tile matrix support in other projections: https://github.com/developmentseed/morecantile. rio-tiler uses that https://github.com/cogeotiff/rio-tiler and, based on that, TiTiler https://github.com/developmentseed/titiler

[dionhaefner]

Sounds like a straightforward PR, then :)