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Re: IDL ROI Objects [message #90120 is a reply to message #90119]

Wed, 28 January 2015 10:17

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Fabien writes:

> See those three examples which are perfectly coherent with each other:

Humm. I guess maybe I should look up "perfectly coherent" in my
dictionary. ;-)

I do note that even Function Graphics gets the notion of a polygon
correct, a result I find especially remarkable:

poly = [[5, 10, 10, 5, 5], [5, 5, 10, 10, 5]]
aplot = Plot([1], XRange=[0,20], YRange=[0,20], /NoData, $
YTickLen=1.0, XTickLen=1.0)
apoly = Polygon(poly[*,0], poly[*,1], /FILL_BACKGROUND, $
FILL_COLOR='Steel Blue', /DATA)

I think if you have to jump through elaborate hoops and rationalizations
to justify results you intuitively can't possibly expect, there is
probably something wrong somewhere.

This would go a long way, too, in explaining why IDLanROI areas don't
jive with areas calculated from, say, chain-code algorithms that also
rely on pixel centers to determine if a pixel is in or out of a polygon.

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.idlcoyote.com/
Sepore ma de ni thue. ("Perhaps thou speakest truth.")

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[Message index]

		IDL ROI Objects By: David B on Tue, 27 January 2015 09:28
		Re: IDL ROI Objects By: David Fanning on Tue, 27 January 2015 10:53
		Re: IDL ROI Objects By: David Fanning on Tue, 27 January 2015 11:00
		Re: IDL ROI Objects By: Fabzi on Tue, 27 January 2015 15:10
		Re: IDL ROI Objects By: David B on Wed, 28 January 2015 02:00
		Re: IDL ROI Objects By: David B on Wed, 28 January 2015 02:06
		Re: IDL ROI Objects By: David Fanning on Wed, 28 January 2015 06:12
		Re: IDL ROI Objects By: David Fanning on Wed, 28 January 2015 06:19
		Re: IDL ROI Objects By: David Fanning on Wed, 28 January 2015 09:17
		Re: IDL ROI Objects By: Fabzi on Wed, 28 January 2015 09:49
		Re: IDL ROI Objects By: David Fanning on Wed, 28 January 2015 10:17
		Re: IDL ROI Objects By: Fabzi on Wed, 28 January 2015 10:30
		Re: IDL ROI Objects By: David Fanning on Wed, 28 January 2015 10:42
		Re: IDL ROI Objects By: Fabzi on Wed, 28 January 2015 10:56
		Re: IDL ROI Objects By: David Fanning on Wed, 28 January 2015 11:20
		Re: IDL ROI Objects By: Fabzi on Wed, 28 January 2015 11:24
		Re: IDL ROI Objects By: David Fanning on Wed, 28 January 2015 11:38
		Re: IDL ROI Objects By: David B on Thu, 29 January 2015 02:05
		Re: IDL ROI Objects By: Fabzi on Thu, 29 January 2015 02:50

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