[postgis-devel] [PostGIS] #240: ST_SimplifyPreserveTopology documentation unclear on intersections within a MultiPolygon

[PostGIS]

#240: ST_SimplifyPreserveTopology documentation unclear on intersections within a
MultiPolygon
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  Reporter:  perchrh  |       Owner:  robe         
      Type:  defect   |      Status:  new          
  Priority:  medium   |   Milestone:  postgis 1.5.0
 Component:  postgis  |     Version:               
Resolution:           |    Keywords:               
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Comment (by kneufeld):

 a forward from Martin Davis...

 The JTS doc for TPS is:

 {{{

 * Simplifies a geometry, ensuring that
 * the result is a *valid *geometry having the
 * same dimension and number of components as the input.
 * The simplification uses a maximum distance difference algorithm
 * similar to the one used in the Douglas-Peucker algorithm.
 * <p>
 * In particular, if the input is an areal geometry
 * ( {@link Polygon} or {@link *MultiPolygon*} ):
 * <ul>
 * <li>The result has the same number of shells and holes (rings) as the
 input,
 * in the same order
 * <li>The result rings touch at <b>no more</b> than the number of touching
 point in the input
 * (although they may touch at fewer points). * *(The key implication of
 this constraint is that the
 * output will be topologically valid if the input was.) *
 * </ul>
 }}}

 Note the bolded text - this answers the question.  If you can think of a
 way to make this clearer, let me know.

-- 
Ticket URL: <http://trac.osgeo.org/postgis/ticket/240#comment:3>
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