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Re: How to define resolution (not dimension!) for IDLanRoi->computeMask [message #65120 is a reply to message #65051]

Tue, 10 February 2009 04:00

justspam03
Messages: 36
Registered: October 2003

Member

Thanks. I've been hacking a bit and it seems in the end I'll extract
the data points
from the ROI, scale them properly, create a 'helper' roi and let the
latter do the
computeMask. The advantage is a.o. that this way I can also non-square
pixels (which
is a requirement).
PolyFillv might not be first choice as it implicitly maps the bounding
box of the 'Roi'
to an integer number of pixels (if I understood that correctly.)

Still, if I may ask again: is anyone aware of the difference between
the 'location' and
the 'pixel_center' keyword of IDLanROI->computeMask?

Cheers
Oliver

On Feb 9, 4:11 pm, David Fanning <n...@dfanning.com> wrote:
> justspa...@yahoo.de writes:
>> eieieiei - I was afraid I'd need to do something like this :-(
>> Well, I guess I'll have my own overloaded computeMask... I anyway
>> subclass from IDLanRoi.
>
> Well, somehow you have to get from a data coordinate system
> into a pixel coordinate system. There are probably other
> ways to do it. I showed you what I do in direct graphics.
> There are certainly comparable methods in object graphics,
> but I don't know what they are. :-)
>

> I suppose you could use the old Scale_Vector/Value_Locate

> trick to find the device values of your ROI:
>
> s = Size(image)
> xvec = Scale_Vector(Findgen(s[0], 1, 5)
> yvec = Scale_Vector(Findgen(s[1], 1, 5)
> xdevice = Value_Locate(xvec, x)
> ydevice = Value_Locate(yvec, y)
> indices = PolyFillv(xdevice, ydevice, s[0], s[1])
>
> I haven't tested that, but it should work. :-)
>
> Cheers,
>
> David
> --
> David Fanning, Ph.D.
> Fanning Software Consulting, Inc.
> Coyote's Guide to IDL Programming:http://www.dfanning.com/
> Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: How to define resolution (not dimension!) for IDLanRoi->computeMask By: David Fanning on Mon, 09 February 2009 07:11
		Re: How to define resolution (not dimension!) for IDLanRoi->computeMask By: justspam03 on Mon, 09 February 2009 06:56
		Re: How to define resolution (not dimension!) for IDLanRoi->computeMask By: justspam03 on Mon, 09 February 2009 06:09
		Re: How to define resolution (not dimension!) for IDLanRoi->computeMask By: ben.bighair on Tue, 10 February 2009 06:13
		Re: How to define resolution (not dimension!) for IDLanRoi->computeMask By: David Fanning on Tue, 10 February 2009 05:52
		Re: How to define resolution (not dimension!) for IDLanRoi->computeMask By: ben.bighair on Tue, 10 February 2009 05:26
		Re: How to define resolution (not dimension!) for IDLanRoi->computeMask By: justspam03 on Tue, 10 February 2009 04:00

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