Opened 9 years ago

Closed 8 years ago

#475 closed defect (invalid)

ST_Simple should return false with duplicate points

Reported by: kneufeld Owned by: pramsey
Priority: low Milestone: PostGIS 2.0.0
Component: postgis Version: trunk
Keywords: Cc:

Description

The OGS specs state: "has no anomalous geometric points, such as self intersection or self tangency" and "is simple if it does not pass through the same point twice". (2.1.5)

The SQL/MM specs state: "is not simple if any interior point has the same location as another interior point or a point on the boundary" (4.1.4)

So, by definition then, this should return false.

select st_issimple(
  'LINESTRING(0 0, 1 1, 1 1)'::geometry
);
 st_issimple 
-------------
 t
(1 row)

Change History (2)

comment:1 Changed 8 years ago by strk

They talk about points, not vertices. Listing the same vertex twice could be just seen as a redundancy but doesn't change the point set defined by the line.

What do other spatial database return ?

comment:2 Changed 8 years ago by pramsey

Resolution: invalid
Status: newclosed

I agree with strk, the language is the language of spatial stuff, not structural stuff.

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