[postgis-users] St_makevalid issue

[Paul van der Linden]

Doesn't anybody have an idea? Or is at least curious?

Especially the select st_isvalid(geo) where not st_valid returning a "true"
row?

>I have a query that gives inconsistent results.
>It almost seems like st_makevalid doesn't always produce the same results
>given the same input, and sometimes even returns invalid geometries...
>
>Results are
>f;1159320407;"Bangladesh"
>f;1159321073;"Mozambique"
>f;1159316737;"Nord"
>f;1159314827;"Uusimaa"
>
>second run:
>f;1159321073;"Mozambique"
>t;1159315455;"Syddanmark"
>t;1159314827;"Uusimaa"
>t;1159317795;"Gerona"
>
>third run:
>f;1159321073;"Mozambique"
>t;1159315455;"Syddanmark"
>
>note the 't' in the second and third run...
>
>Query:
>
>SELECT ST_isvalid(simplifiedgeo2),* FROM (
>SELECT
>    foo2.ne_id,
>    foo2.name,
>    CASE
>        WHEN ST_isvalid(foo2.simplifiedgeo) THEN foo2.simplifiedgeo
>        ELSE ST_makevalid(foo2.simplifiedgeo)
>    END AS simplifiedgeo2
>   FROM (
>     SELECT
>       ST_simplifypreservetopology(foo.geom,
>         LEAST(
>           ST_xmax(foo.shiftedgeo::box3d) - ST_xmin(foo.shiftedgeo::box3d),
>ST_ymax(foo.shiftedgeo::box3d) - ST_ymin(foo.shiftedgeo::box3d))
>         ) AS simplifiedgeo,
>       foo.ne_id,
>       foo.name,
>       foo.geom
>     FROM (
>        SELECT
>          natearth.ne_id,
>          natearth.geom,
>          natearth.name,
>          CASE
>              WHEN (
>                ST_xmax(ST_shiftlongitude(natearth.geom)::box3d) -
>ST_xmin(ST_shiftlongitude(natearth.geom)::box3d))
>                <
>                (ST_xmax(natearth.geom::box3d) -
>ST_xmin(natearth.geom::box3d)
>              ) THEN ST_shiftlongitude(natearth.geom)
>              ELSE natearth.geom
>          END AS shiftedgeo
>          FROM (
>             SELECT
>                ne_10m_admin_0_countries_lakes.ne_id,
>                ne_10m_admin_0_countries_lakes.geom,
>                ne_10m_admin_0_countries_lakes.name
>              FROM natural_earth.ne_10m_admin_0_countries_lakes
>          UNION ALL
>             SELECT
>                ne_10m_admin_1_states_provinces_lakes.ne_id,
>                ne_10m_admin_1_states_provinces_lakes.geom,
>                ne_10m_admin_1_states_provinces_lakes.name
>             FROM natural_earth.ne_10m_admin_1_states_provinces_lakes
>          ) natearth
>     ) foo
>   ) foo2
>) as fff
>WHERE NOT ST_isvalid(simplifiedgeo2)
>
>Any advice on how to further debug this?
>
>"POSTGIS="2.5.1 r17027" [EXTENSION] PGSQL="110" GEOS="3.7.0-CAPI-1.11.0
>3.7.1" PROJ="Rel. 4.9.3, 15 August 2016" GDAL="GDAL 2.2.4, released
>2018/03/19 GDAL_DATA not found" LIBXML="2.7.8" LIBJSON="0.12"
>LIBPROTOBUF="1.2.1" (core procs from "2.5.0 r16836" nee (...)"
>"PostgreSQL 11.2, compiled by Visual C++ build 1914, 64-bit"
>
>Running on windows 64-bit.
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