| Re: IDLgrROIgroup woes [message #32036] |
Mon, 09 September 2002 06:01  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Ben Tupper (btupper@bigelow.org) writes:
> I have bumped into a difficulty using the IDLgrROIgroup container
> object. I have a mixed bag of contours - some are closed and some are
> open - and there exists a variable number of these contours at each
> level (z value). I want to make a an IDLgrROI for each contour at
> each level and then stuff the IDLgrROI into a group container. There
> are three types of ROIs: 0 = points, 1 = open path and 2 = closed
> path. It seems that a given IDLgrROIgroup can contain any of one type
> - but not a mix of types.
>
> So, have I bumped into a bug or am I trying to misuse the
> IDLgrROIgroup?
I think you have discovered an undocumented feature! :-)
It doesn't surprise me that ROIs in an ROI-group have
to be the same type. There are operations you want to
apply to the group (e.g., through the IDLanROIGroup
object) such as computing masks, etc. that would be
impossible given contained ROIs of different types.
If you just want a convenient place to store these
objects, and you don't have any intention of using
the ROIGroup properties, you can use an IDL_CONTAINER,
of course.
Cheers,
David
--
David W. Fanning, Ph.D.
Fanning Software Consulting, Inc.
Phone: 970-221-0438, E-mail: david@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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| Re: IDLgrROIgroup woes [message #32113 is a reply to message #32036] |
Tue, 10 September 2002 13:00  |
btupper
Messages: 55
Registered: January 2002
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Member |
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On Mon, 9 Sep 2002 07:01:05 -0600, David Fanning <david@dfanning.com>
wrote:
>> So, have I bumped into a bug or am I trying to misuse the
>> IDLgrROIgroup?
>
> I think you have discovered an undocumented feature! :-)
>
> It doesn't surprise me that ROIs in an ROI-group have
> to be the same type. There are operations you want to
> apply to the group (e.g., through the IDLanROIGroup
> object) such as computing masks, etc. that would be
> impossible given contained ROIs of different types.
>
> If you just want a convenient place to store these
> objects, and you don't have any intention of using
> the ROIGroup properties, you can use an IDL_CONTAINER,
> of course.
>
Hi and thanks,
Ah! He jauntily juts out his chins and ventures forth into unknown
territory!
I see what you mean about some of the computations... and that makes
sense. This issue has surfaced before for me. I'm handed a number of
contours in X,Y, Value format. These I must display (including
labels) without the benefit of calling CONTOUR - since I have these
contours in hand. Usually it a no brainer - just call PLOTS - but
where to put the labels? Legends are the solution but not
necessarily the one I hoped for. Plus, I want them to be available
for object and direct graphics in one convenient bundle. I was hoping
that IDLgrROIgroup would allow me to organize the contours for given
contour Values together. I think you are right that I should organize
these in my own Container... in this case, an IDLgrModel I suspect.
That way the user can turn various contour Values on/off via the HIDE
property, and I can simply stuff them into an IDLgrView for object
graphics.
This is one of those times when I wish I could make the map
transformations work in object graphics. I keep thinking that a
programmer could set up the map transforms in a hidden DG window -
then copy the scaling and offsets into a OG destination... it seems so
simple in my daydreams!
Thanks again,
Ben
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