[geos-devel] Testing OverlayNG robustness in R-sf

[Roger Bivand]

On Fri, 16 Oct 2020, Martin Davis wrote:

> On Fri, Oct 16, 2020 at 11:59 AM Roger Bivand <Roger.Bivand at nhh.no> wrote:
>
>> Cases 794 and 936 are all-by-all intersections, and as noted in the latter
>> issue, the problems occurring differ by input order.
>>
>
> Well, that's disappointing that 794 and 936 still have failures.
> Especially because 794 was also reported as JTS 300:
>
> https://github.com/locationtech/jts/issues/300
>
> and the test data there is incoporated in the robustness test suilte in
> both JTS [1] and GEOS [2] , where it passes using OverlayNG.
>
> Is there any way to get a dump of the actual input geometries to GEOS which
> are causing these errors?

I've prepared a 13.7GB WKT file (I think - trying to tidy it up), but this 
looks like overkill. My present take after stepping back from the original 
question - which language multipolygons intersect each other and what are 
the combined geometries - to run N=7510 intersections between all and each 
in turn. These did not fail with Overlay-NG, but maybe didn't fail before 
either. All with all was probably an unhelpful understanding of how 
intersection works initially. Further, the list of all-with-each contains 
many non-polygon artefacts, which probably need to be discarded anyway.

So far for now,

Roger

>
> [1]
> https://github.com/locationtech/jts/blob/master/modules/tests/src/test/resources/testxml/robust/overlay/TestOverlay-jts-300.xml
> [2]
> https://git.osgeo.org/gitea/geos/geos/src/branch/master/tests/xmltester/tests/robust/overlay/TestOverlay-jts-300.xml
>

-- 
Roger Bivand
Department of Economics, Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; e-mail: Roger.Bivand at nhh.no
https://orcid.org/0000-0003-2392-6140
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