| On the edge of a polygon...? [message #47920] |
Wed, 15 March 2006 03:50 |
Olivia
Messages: 16
Registered: February 2006
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Junior Member |
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Dear All,
Firstly, apologies for posting on a topic that I know has been covered
a lot - but I cannot find the answer to my query and I am hoping that
someone has brighter ideas than me at the moment :-)!
I am comparing the morphology of ellipses with polygons. I compare the
major axis of an ellipse to the distance between the most distant
vertex points of the polygon, (found for a set of points from
triangulate). Then I find the center x-coordinate on the major axis of
the polygon. I want to find a minor axis comparator - the distance from
the top of the polygon to the bottom of the polygon at x=x0.
So far I have found the equations of the lines connecting the polygon
vertices. Then I solved these lines for x=x0 to find the corresponding
y values. Here's the thing - I tried various ways and lit upon using
IDLanROI:ContainsPoints, which would return a 2, or a 3, for the
(hopefully) 2 points which intersect with the polygon boundary. Only it
doesn't return that at all. In fact, it gives me always one point
inside the boundary, and everything else exterior to the polygon.
This is a lengthy explanantion, but I think I might be going a long way
about this, and cannot figure out why it isn't working. I've messed
around with the accuracy, but everything is working in double.
Any ideas would really be appreciated, cheers,
Olivia
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