st_simplifypreservetopology() fails on some MultiSurfaces

[tvijlbrief]

select st_simplifypreservetopology('MULTISURFACE(((178632.044 397744.007,178631.118 397743.786,178646.399 397679.574,178693.864 397690.889,178698.958 397669.487,178700.206 397669.784,178758.532 397683.689,178748.351 397726.468,178752.199 397727.384,178748.782 397741.904,178744.897 397740.98,178738.157 397769.303,178632.044 397744.007)))'::geometry,1);

ERROR: Unknown geometry type: 12 - MultiSurface

See also: ​https://github.com/postgis/postgis/pull/588

Quote from ​https://postgis.net/docs/ST_SimplifyPreserveTopology.html

Will actually do something only with (multi)lines and (multi)polygons but you can safely call it with any kind of geometry.

but this MultiSurface generates an error

[Algunenano]

I'm wondering if the condition should be a positive one (only continue if the type matches one of the "good" ones) instead, which would make things clearer.

[tvijlbrief]

I agree, that would not only be clearer but we would also be actually simplifying these geometries.

I wonder what the positive condition is, more than 1 sub-geometry or at least one with a curve?

This error is generated somewhere in libgeos, so the cause and correct fix are upstream. My PR proposal is just a workaround.

[tvijlbrief]

The root cause is that MULTISURFACES without curves are not passed to libgeos() but generate an error in the Postgis code. I changed the code in the github PR.

[komzpa]

The problem isn't just Simplify. It's issue with all GEOS functions and should be fixed in converters into GEOS. Generally speaking it should be just downgraded into a collection instead of crash, just like TIN.

select postgis_geos_noop('MULTISURFACE(((178632.044 397744.007,178631.118 397743.786,178646.399 397679.574,178693.864 397690.889,178698.958 397669.487,178700.206 397669.784,178758.532 397683.689,178748.351 397726.468,178752.199 397727.384,178748.782 397741.904,178744.897 397740.98,178738.157 397769.303,178632.044 397744.007)))'::geometry);
ERROR:  XX000: Unknown geometry type: 12 - MultiSurface
LOCATION:  pg_error, lwgeom_pg.c:255

[Paul Ramsey <pramsey@…>]

In 0a083db6/git:

Polish handling of curvilinear geometry types being
sent to GEOS. GEOS only takes linear types, so all
curvilinear types need to be (a) stroked and (b)
re-typed to a linear type. The lwgeom_has_arc() function
is to exact for that work: it will correctly note
that curve types with no curve components have no arc.
So a new broader test for any type that *might* have
an arc is added, to handle the GEOS transformation
situation.
Closes #4796