Charlie, this is not a problem. Floating point rounding error only
comes into play when you are doing computations using numeric
operations. Extent computation only uses comparison operations, and
these are exact. So if a BBox is computed for a geometry and it has the
max and min x and y being exactly the same, it can be determined to be a
Point, with no worry about error. (Conversely, if a geometry is not a
point, it must have at least two coordinates with different Xs or Ys,
and so its BBox will have a non-zero extent.
Charlie Savage wrote:
PostgreSQL will rewrite Centroid(Extent()) to
Centroid(Box2Geom(Extent())
Right. I was thinking more about how you would change Box2Geom to
recognize the extent is actually a point (being wary of comparing
floating point numbers).
Charlie
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Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022
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