[R-sig-Geo] downsampling a lines shapefile?

Hadley Wickham hadley at rice.edu
Sun Oct 30 09:53:05 CET 2011

> GEOS is neutral, and the GEOS nomenclature is misleading IMO. Because the
> process treats each ring (polygons) separately, all that is preserved are
> the nodes where three rings touch, but not the boundaries between two
> polygons, which may generate empty slivers, or overlap. I would have taken
> the term to imply that if input rings shared all boundary points between
> nodes, then they would be simplified identically, but this is not the case.
> To get this (desirable) behaviour, you need a topological vector GIS, like
> GRASS. Since I feel that the GEOS name is misleading, the default is FALSE,
> but I'm open to better ideas.

Ah, thanks.  This sort of simplification has been on my to do list to
implement for a long time, but unfortunately it's pretty low priority.
 If I have to, I do simplification by hand with http://mapshaper.org/
- I've tried, with no luck, to contact the authors to find out how
they're implementing it so quickly.


Assistant Professor / Dobelman Family Junior Chair
Department of Statistics / Rice University

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