[postgis-users] negative buffer

Torsten Lange tlange at gwdg.de
Tue Jan 20 12:10:47 PST 2009


I have polygons with sometimes very peculiar shapes representing the 
distribution limits of specific types of sediments (e.g. channel-like 
branching, fluvial fans...). When I try to create positive and negative 
buffers of that polygons using the combined 
(st_buffer(st_simply(geom,i)j)-method I succeed only in positive 
direction. In negative direction it very fastly violates 
enforce_geotype_geom-check. When I look on the last results I see, it is 
related to the channel-like branches. Using the buffer-method in ArcGIS 
it works as expected. Is there a clever method getting it work in 
PostGIS too?

Thank you, Torsten

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