Charlie Savage wrote:
Hi Martin,
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.
Ah - that's interesting.
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.
Thanks for the information. Ok, then I'll see if I can fix up the bbox2
to geometry conversion so it returns a point if either xmin=xmax or
ymin=ymax. Currently it returns an invalid polygon - same problem that
envelope had.
Hmmm... for an linear envelope would returning a linestring not make
more sense?
Charlie
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Paul Ramsey
Refractions Research
http://www.refractions.net
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Phone: 250-383-3022
Cell: 250-885-0632
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