Functions of `loxodrome` or `rhumb line` is needed

[AkexStar]

I have did a lot of surveys, but found that there is few libs about rhumb_inverse and rhumb_direct. I noticed that Geographiclib has a solution for rhumb, but does not support python. pyproj has geodesic.inv_intermediate and geodesic.fwd_intermediate for great-circle(geodesic), but lacks of functions to calculate rhumb line.

Rhumb Line is very important for air/sea track calculation. I hope that there will be funtions just similar to geodesic.fwd_intermediate to compute rhumb line.

I will be very grateful if any developer could reply me.

[snowman2]

The geodesic functions use c functions from PROJ which are imported from the GeographicLib library you reference (https://proj.org/en/9.2/geodesic.html). To get the logic in pyproj, the logic will need to be added to PROJ first.

See: https://github.com/OSGeo/PROJ/

[AkexStar]

@snowman2 Thank you! I'll go to PROJ and raise an Issue

[snowman2]

Related:

• https://github.com/jrversteegh/geofun
• https://github.com/OSGeo/PROJ/issues/3855

[jjimenezshaw]

Some people showed in the ticket in PROJ (https://github.com/OSGeo/PROJ/issues/3855) how to easily compute a loxodrome using the Mercator projection. Should this issue be closed?

[snowman2]

Do you think that their suggestion is worth documenting?

[jjimenezshaw]

https://github.com/OSGeo/PROJ/issues/3855#issuecomment-1698098657 I don't know if it is worth it, maybe.