[postgis-devel] [PostGIS] #1535: Negative distance argument to ST_Buffer not documented

PostGIS trac at osgeo.org
Fri Feb 3 01:23:07 PST 2012

#1535: Negative distance argument to ST_Buffer not documented
 Reporter:  rutsky         |       Owner:  robe         
     Type:  defect         |      Status:  new          
 Priority:  medium         |   Milestone:  PostGIS 2.0.0
Component:  documentation  |     Version:  1.5.X        
 Keywords:  buffer         |  
 Documentation to ST_Buffer [1] says that argument "radius_of_buffer" is
 distance and defines buffer operation as "all points whose distance from
 this Geometry/geography is less than or equal to distance".

 Documentation implies that ST_Buffer can buffer only on positive values
 which isn't correct as I see in practice, and since ST_Buffer is
 implemented using GEOS it is possible to buffer on negative distances [2].

 [1] http://www.postgis.org/docs/ST_Buffer.html


Ticket URL: <http://trac.osgeo.org/postgis/ticket/1535>
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