[PostGIS] #5765: Incorrect distance between geography polygons

[PostGIS]

#5765: Incorrect distance between geography polygons
------------------------+---------------------------
 Reporter:  Mike Taves  |      Owner:  pramsey
     Type:  defect      |     Status:  new
 Priority:  medium      |  Milestone:  PostGIS 3.4.3
Component:  postgis     |    Version:  3.1.x
 Keywords:              |
------------------------+---------------------------
 Looking into https://lists.osgeo.org/pipermail/postgis-
 users/2024-July/046496.html there appears to be issues with a few distance
 functions on polygons with geographic coords. Running the same query on a
 few docker images it appears this been broken since version 3.1.

 Here is a query that does several distance methods between two
 valid/simple polygons:
 {{{#!sql
 SELECT ST_Distance(ST_Transform(A, 27700), ST_Transform(B, 27700)) AS
 distance_27700,
   ST_DistanceSpheroid(A, B, 'SPHEROID["WGS 84",6378137,298.257223563]') AS
 DistanceSpheroid,
   ST_DistanceSphere(A, B) AS DistanceSphere,
   ST_Distance(A::geography, B::geography, true) AS
 distance_geography_spheroid,
   ST_Distance(A::geography, B::geography, false) AS
 distance_geography_sphere
 FROM (
  SELECT
   ST_GeomFromText('POLYGON ((-1.7485534738529238 52.477989324720184,
 -1.7485528426344397 52.47797089391474, -1.748563887653701
 52.47797046786393, -1.7485727216213993 52.47797048661752,
 -1.7485733502887397 52.47798936691661, -1.7485739840754728
 52.478007348228196, -1.748563677771212 52.47800732634904,
 -1.7485541076315525 52.47800730603188, -1.7485534738529238
 52.477989324720184))', 4326) AS A,
   ST_GeomFromText('POLYGON ((-1.748665164272404 52.47789651546308,
 -1.748705653223533 52.477896601376905, -1.7487057222918938
 52.47788446504611, -1.7487307518185344 52.47788451814952,
 -1.7487299491521497 52.47789620342481, -1.7487660211267058
 52.477896279947124, -1.748767153309673 52.477956065736684,
 -1.7486648265496951 52.477955848635304, -1.7485639721184771
 52.477955634571074, -1.7484653236191374 52.47795587460495,
 -1.748465659049668 52.47789699092737, -1.7485017310241382
 52.477897067530265, -1.7485018001486063 52.47788493119968,
 -1.7485297717654242 52.47788544009214, -1.7485297103282949
 52.477896227941585, -1.748562835091827 52.47789674776739,
 -1.7485996432291142 52.47789682590328, -1.7485997123266428
 52.47788468957258, -1.7486276865033974 52.47788474894817,
 -1.748627619972449 52.477896435785155, -1.748665164272404
 52.47789651546308))', 4326) AS B
 ) AS data;
 }}}
 With PostGIS 3.0 (via `postgis/postgis:10-3.0`) here is the expected
 result:
 {{{
 -[ RECORD 1 ]---------------+-----------------
 distance_27700              | 1.64995405783897
 distancespheroid            | 1.65055968246111
 distancesphere              | 1.64935316
 distance_geography_spheroid | 1.65055968
 distance_geography_sphere   | 1.64935316
 }}}
 whereas with PostGIS 3.1 (via `postgis/postgis:10-3.1`) here is the
 malformed result:
 {{{
 -[ RECORD 1 ]---------------+-----------------
 distance_27700              | 1.6499540575588
 distancespheroid            | 1.65055968246111
 distancesphere              | 0
 distance_geography_spheroid | 0
 distance_geography_sphere   | 0
 }}}
 and similar results with the latest docker images (PostGIS 3.4.2):
 {{{
 -[ RECORD 1 ]---------------+-------------------
 distance_27700              | 1.649954057558797
 distancespheroid            | 1.6505596824611086
 distancesphere              | 0
 distance_geography_spheroid | 0
 distance_geography_sphere   | 0
 }}}

 Based on the above, there appears to be some issues with:
 * `ST_Distance(geography, geography)`
 * `ST_DistanceSphere(geometry, geometry)`

 And to be clear, there are no issues with:
 * `ST_Distance(geometry, geometry)`
 * `ST_DistanceSpheroid(geometry, geometry, spheroid)`
-- 
Ticket URL: <https://trac.osgeo.org/postgis/ticket/5765>
PostGIS <http://trac.osgeo.org/postgis/>
The PostGIS Trac is used for bug, enhancement & task tracking, a user and developer wiki, and a view into the subversion code repository of PostGIS project.