| Re: objects ROIS [message #16086] |
Tue, 29 June 1999 00:00 |
davidf
Messages: 2866
Registered: September 1996
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Senior Member |
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gabriel rodriguez ibeas (gabriel@gbt.tfo.upm.es) writes:
> I would like to know if anybody has ever worked with ROIS and
> Graphics Objects. What I would like to do is define a ROI trough user
> interaction in a DRAW_WIDGET, (object type) and get all the index of a
> IDLgrImage data that lie within the roi (I thick the procedure DEFROY
> does something similar, but with direct graphics)
>
> I would appreciate some basic tips to start playing arount, but I
> would not mind at all a closed program that did something similar.
A draw widget is a draw widget, whether you are putting direct
graphics into or object graphics. The most you can get out of
a draw widget when you are moving the cursor inside it are
a series of *locations* in the draw widget window, usually in
device coordinates.
It is up to you as a programmer to turn those locations
into something meaningful. This is as true in direct graphics
as it is in object graphics. Making meaningful inferences
about locations is made infinitely easier if there is a one
to one correlation between the location in the window and
the same location in the image. But, again, this has
absolutely nothing whatsoever to do with what kind of
graphic system you choose to use.
I would have to think a good long time, however, for
a reason to use object graphics images over direct
graphics images. (Any application that required
alpha channel capability would be one.)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting
Phone: 970-221-0438 E-Mail: davidf@dfanning.com
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Toll-Free IDL Book Orders: 1-888-461-0155
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