[postgis-users] Geometries returning zero area with PostGIS 3.1.2.

[Paul Ramsey]

Marco,
Can you open a ticket and attach some WKT to said ticket? That way I can test it without having to learn how to extarct those relations from OSM myself.
Thanks!
P

> On Jul 11, 2021, at 3:42 AM, Marco Boeringa <marco at boeringa.demon.nl> wrote:
> 
> Hi all,
> 
> I am running into an issue with two of OpenStreetMap's polygon geomtries returning a zero area for the following PostGIS SQL clause:
> 
> ST_Area(ST_ConvexHull(ST_Transform(way,4326))::geography,true)
> 
> Note that the data was imported using osm2pgsql, with the data stored in WGS1984, not Web Mercator.
> 
> The two relations that cause the issue are:
> 
> https://www.openstreetmap.org/relation/2186646 <https://www.openstreetmap.org/relation/2186646>
> 
> https://www.openstreetmap.org/relation/3394113
> 
> One represents "Antarctica", the other the "Ross Dependency".
> 
> Note that both relations appear to be quite old (years), and I am therefor pretty sure I have processed the exact same geometries previously without issues with older versions of PostGIS after planet import. Note also that both geometries test as valid with "ST_Isvalid(way)" after import using osm2pgsql.
> 
> Has something changed in the latest PostGIS 3.1.2 that might explain this result, e.g. especially related to the "::geography" cast or the "ST_ConvexHull" statement?
> 
> Of course, in the way these geometries wrap the globe, they may represent a challenge, but as said, I am pretty sure I must have processed the same geometries without issues in previous releases of PostGIS.
> 
> Marco
> 
> 
> 
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