[fdo-users] MPolygon <-> FDO

djonio djonio at miami-airport.com
Sat Mar 8 06:46:48 EST 2008

1) ...."it would be a good precaution to add code to coerce the starting and
ending positions of each ring to match exactly.  That is, the last position
of the last curve segment should be assigned as a copy of the first position
of the first curve segment."
2)... "floating point drift"
3) .... "Overriding the last XY ordinates (using the first ones) used to
create the geometry should fix this."

I am not the brightest bulb on the tree but it looks like CurveString and
Ring are pretty much broken. At best they are totally unreliable.

In rereading this thread it would appear you have know all along that these
methods are a best, flawed. Ok, I can take a little "guided discovery". Not
the most time conserving approach to learning but, OK.

What are the plans to fix these methods? 


Hi, Dennis.  Sorry for the delay.  Yes, trying to create CurveStrings is a
good test, and easy since both the Ring and CurveString types are created
from a CurveStringCollection.

While text conversions can hide small floating point drift, I can see some
drift in your first case.  The last X value is -9.50149754820001, with that
trailing 0001 being drift.  This CurveString would probably return false in
its "IsClosed" method.  Overriding the last XY ordinates (using the first
ones) used to create the geometry should fix this.


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