| Re: Image scale as 0 - 4096 instead of 0 - 255 [message #29943 is a reply to message #29908] |
Tue, 26 March 2002 16:45   |
Mark Hadfield
Messages: 783
Registered: May 1995
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Senior Member |
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"Akhila" <idlfreak@yahoo.com> wrote in message
news:b1ad7b05.0203261438.19606cd0@posting.google.com...
> I can display two images in two different windows in direct graphics
> like this:
>
> ...
>
> I want to display the two images this way in two windows but in
> object graphics. I tried to do the following in object graphics, but
> didn't help.
>
> oImage = Obj_New('IDLgrImage', image, ORDER = 2)
> oWindow = Obj_New('IDLgrWindow')
> oView = Obj_New('IDLgrView', VIEWPLANE_RECT = [0,0,512,512], COLOR =
> [0,0,0], PROJECTION = 2)
> oModel = Obj_New('IDLgrModel')
> oModel -> Add, oImage
> oView -> Add, oModel
> oWindow -> Draw, oView
>
> and again for image1.
>
> ...
Hmmm. I think it's a redrawing problem. If I run your code on my
system (IDL 5.5, Windows 2000, hardware renderer) I get two object
graphics windows, one on top of the other. The image is visible in the
second window (ie. the one initially visible), but when I expose the
first window it's black. Then when I expose the first window it's
black also. And they both stay black thereafter, because the
IDLgrWindow objects don't retain their contents and they're not being
redrawn on exposure.
A simple fix is to set the RETAIN property of the IDLgrWindows to
something other than 0. (Possible values are 1 & 2. On Windows they
give identical results. On Unix it depends on X backing store and
other complicated stuff--try them both.)
The basic problem is that Object Graphics provides quite a nice
toolkit for scientific visualisation, but it's all very
low-level. Plain IDLgrWindow objects are not really very useful. You
need an object-graphics window embedded in a widget application with
event-handling code to take care of redrawing. You could display each
of your IDLgrImage objects with XOBJVIEW. Or you roam through David
Fanning's WWW site looking for something suitable. My IDL libray has a
general-purpose OG window object (MGH_Window) that could be just what
you need. It's at
http://katipo.niwa.cri.nz/~hadfield/gust/software/idl/
As I've explained recently on this group, my library is not as
user-friendly as some others. But you're welcome to try it out and I'd
love to hear how you get on.
--
Mark Hadfield
m.hadfield@niwa.co.nz Ka puwaha et tai nei
http://katipo.niwa.co.nz/~hadfield Hoea tatou
National Institute for Water and Atmospheric Research (NIWA)
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