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

[Marco Boeringa]

Hi Paul,

Done:

https://trac.osgeo.org/postgis/ticket/4951

Note that I copied the WKT representation straight from DBeaver's 
display of it in the table view. Seems to work fine though... I tested 
displaying the files in a browser based WKT renderer, and it appeared OK.

Marco

Op 12-7-2021 om 21:46 schreef 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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