[postgis-users] ST_Area(geog): ptarray_area_spheroid: cannot handle ptarray that crosses equator

[Regina Obe]

Hmm something seems a little fishy with this.  I'm running 2.3.3 so I guess it's possible it's something we fixed in PostGIS 2.3.3.

 

When I run:

 

SELECT ST_Area(ST_GeographyFromText('POLYGON((40 0.009,40.1 0.009,40.1 0,40 0,40 0.009))'));

 

I get:

 

11078167.65815

 

I think since version 2.2.0 or 2.3, I forget which, the geographicLab library (which requires Proj 4.9+) kicks in so it's possible I'm not having the same issue because I'm using a newer Proj version so I'm using the improved calc stuff.

 

This is the version I'm using.

 

POSTGIS="2.3.3 r15473" GEOS="3.6.1-CAPI-1.10.1 r4317" PROJ="Rel. 4.9.1, 04 March 2015" GDAL="GDAL 2.2.1, released 2017/06/23" LIBXML="2.7.8" LIBJSON="0.12" RASTER

 

 

 

 

 

From: postgis-users [mailto:postgis-users-bounces at lists.osgeo.org] On Behalf Of Peter Schmitt
Sent: Monday, August 21, 2017 4:31 PM
To: postgis-users at lists.osgeo.org
Subject: [postgis-users] ST_Area(geog): ptarray_area_spheroid: cannot handle ptarray that crosses equator

 

Hi,

 

The following query:

 

>  SELECT ST_Area(ST_GeographyFromText('POLYGON((40 0.009,40.1 0.009,40.1 0,40 0,40 0.009))'));

 

returns the error: 

 

> ptarray_area_spheroid: cannot handle ptarray that crosses equator

 

I am using Postgis-2.3 provided by https://hub.docker.com/r/mdillon/postgis/

 

postgis_full_version =  POSTGIS="2.3.2 r15302" GEOS="3.4.2-CAPI-1.8.2 r3921" PROJ="Rel. 4.8.0, 6 March 2012" GDAL="GDAL 1.10.1, released 2013/08/26" LIBXML="2.9.1" LIBJSON="0.11.99" RASTER

 

I believe the geometry is valid.  I can pass the error by setting use_spheroid=false, like so:

 

> SELECT ST_Area(ST_GeographyFromText('POLYGON((40 0.009,40.1 0.009,40.1 0,40 0,40 0.009))'), false);

 

However, I would like to use the sphere everywhere else in my application.  Can anyone provide some insight?  I found something reporting this should not hapen on Postgis >= 2.2: https://gis.stackexchange.com/questions/169436/postgis-polygons-lying-on-the-equator/169482#169482

 

Thanks!

Pete

 

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