[geos-devel] Possible speed improvement for overlay operations

[Darafei "Komяpa" Praliaskouski]

>
> Other ideas about performance improvements are welcome.  For instance, I
> have had some ideas about only noding geometry in the region of actual
> overlap in the case of an intersection computation.  That probably has
> implications for robustness, however.  Needs some research...
>


I tried to implement this speed up in PostGIS via box clipping.
Current GEOS recangle clipping is unfortunately not robust, but helps quite
a lot when not crashing.

I tried redoing clipping by doing just O(N) clamping to the box. Result
retains many required properties (ie, raycasting will give correct
inside/outside result for it, area is okay) but has holes touching edges
and edges touching themselves. GEOSIntersection can't handle that.

Is there a simple way to recover the boundary for such geometry to feed
further to GEOSIntersection? Buffer(,0) does not help in many cases,
ST_MakeValid too.

Can we make GEOSIntersection handle such invalid input, or is it completely
incompatible with monotone chain conception?
-- 
Darafei Praliaskouski
Support me: http://patreon.com/komzpa
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