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Re: making a circle of certain values [message #56106]

Wed, 03 October 2007 01:42

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

David Fanning <david@dfanning.com> writes:
> rpertaub@gmail.com writes:
>
>> I have a set of data points (x,y coordinates) that can be plotted on
>> my 1240,1024 array. However, they are sparse x,y spots across the
>> image, and I want to 'thicken' it by drawing a circle with my x,y as
>> centers. I want to give it a certain radius and a certain value too,
>> so that the pixels in the circle (the filling) have values and can
>> thus contribute to my rgb image...
>> anyone know how to draw a circle, and assign a value to pixels within
>> that circle?
>
> I'd use the most useful routine I ever downloaded from the NASA
> Astronomy library: TVCIRCLE.
>
> You will probably have to write a new output keyword for that routine
> to recover the XY locations of the polygon it creates for the circle.
> Then use POLYFILLV to find the indices of the image inside that polygon.
>

Hmm, I just use this all the time:

pro circsym, _EXTRA=extra
theta=findgen(26)*0.251327412
xsym=cos(theta)
ysym=sin(theta)
usersym, xsym, ysym, _EXTRA=extra
return
end

either with CIRCSYM by itself, or CIRCSYM, /FILL, and then I'm ready
to plot with PSYM=8 and whatever SYMSIZE I want. And the circles stay
round!

Craig

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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@REMOVEcow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: making a circle of certain values By: Craig Markwardt on Wed, 03 October 2007 01:42
		Re: making a circle of certain values By: David Fanning on Tue, 02 October 2007 09:33
		Re: making a circle of certain values By: Loren Anderson on Tue, 02 October 2007 09:30
		Re: making a circle of certain values By: David Fanning on Tue, 02 October 2007 08:43
		Re: making a circle of certain values By: Loren Anderson on Tue, 02 October 2007 08:24
		Re: making a circle of certain values By: Jean H. on Mon, 01 October 2007 13:21
		Re: making a circle of certain values By: David Fanning on Mon, 01 October 2007 13:09

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