Freeze hard-coded prime meridians and note they are no longer updated #4042
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| @@ -580,8 +580,11 @@ int main(int argc, char **argv) { | |||
| } | |||
| proj_unit_list_destroy(units); | |||
| } else if (arg[1] == 'm') { /* list prime meridians */ | |||
| (void)fprintf(stderr, | |||
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I wouldn't emit a warning. If we want to emit one, then we should also do it for datum, ellipsoid, units, etc
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I'm fine with the second sentence "This list is no longer updated, and some values may conflict with other sources"
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Listing datums was already removed (e9605e4).
Listing ellipsoids could potentially show a similar message.
Listing units uses proj_get_units_from_database so is fine.
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Feel free to disregard my comments. I'm not that strong about them.
The only thing that is a bit weird is that internally PROJ still creates PROJ pipeline strings with those deprecated features, but one could argue that is an implementation detail. Well, actually not completely true, as we also export that to the sight of the advanced user...)
$ bin/projinfo -s "NTF (Paris)" -t "NTF" -o PROJ -q
+proj=pipeline
+step +proj=axisswap +order=2,1
+step +proj=unitconvert +xy_in=grad +xy_out=rad
+step +inv +proj=longlat +ellps=clrk80ign +pm=paris
+step +proj=unitconvert +xy_in=rad +xy_out=deg
+step +proj=axisswap +order=2,1
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I think it's fine to have a short list of hard-coded of prime meridians (e.g. where paris ↔ 2.33722917) with the caveat that it doesn't change. It's a bit deprecated, but I wasn't planning to establish this as a deprecated feature. But yes, I can tone down the "legacy PROJ.4" wording throughout.
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The above pipeline could also have +pm expressed in decimal degrees, so the PROJ internals could be changed to do that in the future, should we decide to drop support for these hard-coded lists.
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| @@ -580,8 +580,11 @@ int main(int argc, char **argv) { | |||
| } | |||
| proj_unit_list_destroy(units); | |||
| } else if (arg[1] == 'm') { /* list prime meridians */ | |||
| (void)fprintf(stderr, | |||
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The above pipeline could also have +pm expressed in decimal degrees, so the PROJ internals could be changed to do that in the future, should we decide to drop support for these hard-coded lists.
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Thanks for feedback @kbevers. I've taken the moment to further expand the docs on angular inputs too, which I wouldn't mind a bit of review on too. |
Looks great. Good job! |
This PR "freezes" hard-coded prime meridians that are listed in
src/datums.cpp'sPJ_PRIME_MERIDIANSstruct. This has only had a few modifications since it was added 22 years ago (27c197f), but has some omissions (#4031) and some values conflict with other sources (#4029, #4030). Also, there are potentially many other prime meridians that users may want to choose from.This PR doesn't go as far as deprecating
cs2cs -lm, actually it adds this missing doc item. However, a message is sent to stderr:Suggestions in rewording or changing tone are welcome.
This also updates docs/source/usage/projections.rst with a few corrections. The example is changed from
madrid(which "has had various determinations", including 84b8264) tolisbonwhich I assume has stayed put there for a while now.Closes #4031, #4029