[OpenMap Users] OMCircle Distortion?

From: Christopher Franklin <christopher.franklin_at_lmco.com>
Date: Mon, 28 Jul 2008 14:37:06 -0400

Greetings,

I am working on a project that requires a user to select an area on the
map by using a circle. The user clicks to select the center and then
again to select the edge (radius). I am using an OMCircle because it
exhibits the proper behavior for a circle on a globe.

I have noticed a problem with the OMCircle though. After drawing it
using the provided center and radius I am adding a graphic to represent
the center and another to represent the rightmost edge of the circle.
When the circle is drawn on or near the equator everything appears
correct. However, if the circle is drawn north or south there is a
noticeable distortion in how the circle and the edge handle are drawn. I
have done some experimentation and discovered that the handle is being
drawn in the correct location, but the edge of the circle is not. The
further away from the equator the greater the discrepancy between my
handle location and the OMCircle edge. If, however, I move the handle to
the top of the circle it is always drawn in the correct location. For
usability purposes I would like the handle to be on the right hand side!
Is there a way to fix this? If not, I guess they will have to deal with
the handle being on the top or bottom of the circle...

Another problem I would like to bring up is when zoomed in to a small
area (~1m scale) the OMCircle draws as a polygon approximation of a
circle. Is there a way to increase the number of segments being drawn at
that low of scale?

Thanks in advance for any help!
Chris Franklin
MES
LMCO - ATL

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Received on Mon Jul 28 2008 - 14:38:19 EDT

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