[postgis-tickets] [PostGIS] #4949: Transform regression for N, E CRS

[PostGIS]

#4949: Transform regression for N,E CRS
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  Reporter:  rcoup    |      Owner:  pramsey
      Type:  defect   |     Status:  new
  Priority:  medium   |  Milestone:  PostGIS 3.1.3
 Component:  postgis  |    Version:  3.1.x
Resolution:           |   Keywords:
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Comment (by rcoup):

 PostGIS/etc has always done E/N with 2193 (& a group of associated local
 circuit CRS) since I started working with it >15 years ago.

 With CRS WKT1 the axes were never really were visible (even now `SELECT
 srtext FROM spatial_ref_sys WHERE srid=2193;` doesn't show it), everything
 was always treated as X/E/Lng, Y/N/Lat. Same as EPSG:4326 ;-) And proj4
 didn't do axis ordering AFAIK.

 Maybe becomes a larger question (PostGIS 4?):
 1. Should postgis support axis ordering ala the CRS defintion?
 Fundamentally, probably yes.
 2. Should postgis continue to store data in XYZM order? In which case,
 seems like axis ordering is an operation to apply only at
 input/output/transform time.
 3. Or should it be storing data in the CRS order? In which case, seems
 like many beahviour/definitions need to change wrt functions? eg:
 `ST_XMax()` returns "first axis" not X/E/Lng. And the IO-time/SetSRID
 operations need to change to flip as appropriate.
 4. What's the path for a user to migrate from what they have now? Options
 at a function/geometry/column/user/session/database level?

 WRT a simpler fix for the regression though...

 Should `ST_Transform()` be calling
 `proj_normalize_for_visualization()`([https://proj.org/development/reference/functions.html#_CPPv432proj_normalize_for_visualizationP10PJ_CONTEXTPK2PJ
 ref])? Then we can say everything is X/Lng/E, Y/Lat/N ala all other
 PostGIS versions, and continue to ignore the CRS axis ordering.

-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/4949#comment:6>
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