[geos-devel] what happened to my digits ?

Sandro Santilli strk at kbt.io
Tue Aug 18 13:17:42 PDT 2020


On Mon, Aug 17, 2020 at 01:45:41PM -0700, Martin Davis wrote:
> Would it be this one?
> 
> https://github.com/libgeos/geos/commit/bacd58058025b25de93fb23bb78ff540ef1e3b63
> 
> Paul was having some issues with output precision, but I can't remember the
> details.  He made some kind of fix - perhaps this one.

Yes, this was the one.

> Agreed that the output in sci not for such small numbers is not useful.

Not really. I'd revert. Look what output we get here, with that commit
reverted:

        Description: AA - A hole close to shell, B coincident with A
        Geometry A: POLYGON ((10 100, 10 10, 100 10, 100 100, 10 100), (90 90, 11 90, 10 10, 90 11, 90 90))
        Geometry B: POLYGON ((10 30, 10 10, 30 10, 30 30, 10 30))
        Expected result: MULTILINESTRING ((10 10, 30 10), (10 10, 10 30))
        Obtained result: MULTIPOINT (30 10, 10 30)

Pretty clear. Now to find out WHY we get the wrong result with
OverlayNG... (JTS passes)

I've filed https://trac.osgeo.org/geos/ticket/1044 to tackle this

--strk;


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