[PROJ] About PROJ.6: Radians or Degrees ?

[Kristian Evers]

Sorry for the inconvienence! This is a leftover from PROJ 5 were angular
coordinates could in fact only be interpreted as being radians. I've
updated the docs now so that they are more specific in this matter:
https://proj4.org/development/reference/functions.html#c.proj_angular_input

It would probably also be smart to add aliases to those two functions.
Something like proj_input_is_radians() and proj_output_is_radians().
Or, alternatively make sure that radians are never expected where
degrees is actually used (e.g. proj_create("+proj=utm +zone=32")
would expect degrees and not radians as today).

I am leaning towards the latter solution but it is also the most difficult
to implement... Something to think about for the 7.0 release.

/Kristian

-----Oprindelig meddelelse-----
Fra: a.furieri at lqt.it <a.furieri at lqt.it> 
Sendt: 2. april 2019 14:33
Til: Kristian Evers <kreve at sdfe.dk>
Cc: Even Rouault <even.rouault at spatialys.com>; proj at lists.osgeo.org
Emne: Re: SV: [PROJ] About PROJ.6: Radians or Degrees ?

On Tue, 2 Apr 2019 10:52:25 +0000, Kristian Evers wrote:
>> Kristian, perhaps the documentation should explicitly mention that 
>> angular
> here must be understood as radian ?
>
> Yes, I agree. I'll update the docs for those two functions right 
> away.
>

Hi Kristian and Even,

thanks a lot for your clarifications.
As far as I'm concerned this definitely resolves any trouble;
calling proj_angular_input() and/or proj_angular_output()
effectively is all that is required in order to safely determine
if coordinate values must be passed (or returned) expressed in
Radians or Degrees.
it's nice and effective.

the documentation absolutely needs to be expanded/clarified;
I personally spent several hours attempting to resolve this
puzzling issue because my mind was stuck in intending
"angular" as a synonym for "geographic/latlong/longlat",
so I was completely unable to figure out that it was
intended to really mean "radians".

bye Sandro