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Ellipse fitting? [message #66407]

Tue, 12 May 2009 13:36

robparker23
Messages: 10
Registered: March 2009

Junior Member

Hi,

I was hoping that someone could help with this.

I have a satellite footprint which is more or less elliptical. I have
the 4 coordinates of the top, bottom, left and right-most points and
want to fit an ellipse to these 4 coordinates.

I've put a diagram here to explain: http://img217.imageshack.us/img217/5048/ellipse.png

I've googled this quite a bit and there seem to be lots of ways to fit
ellipses to complicated data sets using techniques like optimal
estimation but I can't find an easy/quick way of doing it. To do this
manually I think I could just take the equation for an ellipse and
adjust it to fit but I need to do this automatically for a large
number of points where the shape of the ellipse will change depending
on the location.

This gets slightly more complicated (doesn't it always) as the shape
may not quite be an ellipse due to the geometry of the satellite (it
might have one side slightly "fatter" than the other) and it might be
titled at an angle (so not horizontal).

Does IDL have any ellipse fitting capabilities built in or is anyone
familar with a solution that might work?

Cheers

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[Message index]

		Ellipse fitting? By: robparker23 on Tue, 12 May 2009 13:36
		Re: Ellipse fitting By: Oriol Güell Riera on Thu, 09 September 2010 11:55
		Re: Ellipse fitting By: Jeremy Bailin on Thu, 09 September 2010 06:50
		Re: Ellipse fitting By: Kenneth P. Bowman on Thu, 09 September 2010 06:29

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