| Re: Object graphics output police (iImage) [message #44088] |
Fri, 13 May 2005 10:24 |
Randall Skelton
Messages: 31
Registered: October 2004
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Member |
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Many thanks for the replies. However, I thought this was a 'simple'
graphic ;) In my real plot, the bitmap image is included to try and
give some sense model grid-box size before adding contours, wind
vectors, and symbols/text annotations for various observations. Thus,
there are real, vectors that I'd like to preserve in the output as
well. The truely correct way of doing this probably involves drawing
each grid-box as a filled polygon but I was trying to cheat. Yes, the
'square' pixels aren't perfect, but they'd get my point across in this
case.
More generally, my obsession with vector graphics stems from them
generally being a more flexible and useful format. Licensing restricts
me to using IDL when connected to the net so if I need to edit some
text quickly I can fire up Adobe illustrator or Corel draw and simply
edit the text. Likewise, with fine adjustments of arrows and axes and
the thickness of certain contour lines. Lastly, It is common practice
for nice, illustrative figures to be recycled for years--- long after
the people/scripts that created them have disappeared.
Trying to quickly edit a bitmap image is an absolute nightmare and it
never looks as good as it should when you are done. The default image
sizes being output by IDL (and iTools in particular) generally result
in very poor quality figures for paper publications. I know it isn't
rocket science but, if I had a nickel for every time I've seen a
powerpoint talk or a paper with badly scaled bitmap figures, I'd be
wearing gold suits.
I'll probably just revert to using filled contour lines and forget
about the grid boxes for the moment.
Cheers,
Randall
NB: who do I write to for requesting getting native pdf output again?
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| Re: Object graphics output police (iImage) [message #44090 is a reply to message #44088] |
Fri, 13 May 2005 09:42  |
Randall Skelton
Messages: 31
Registered: October 2004
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Member |
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I had really hoped this would work, but I wasn't entirely suprised that
it failed. For those of us who need to publish figures, it is rather
important that the vector postscript be correct. Karl has made some
fantastic improvements with the vector postscript output in OG in 6.1.1
so perhaps he can work some magic with this as well.
Cheers,
Randall
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| Re: Object graphics output police (iImage) [message #44091 is a reply to message #44090] |
Fri, 13 May 2005 09:41 |
Karl Schultz
Messages: 341
Registered: October 1999
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Senior Member |
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On Fri, 13 May 2005 09:34:03 -0600, David Fanning wrote:
> Randall Skelton writes:
>
>> Can someone explain if there is a way to 'fix' the iTools problem
>> demonstrated in the code below. The problem is that the image plotted
>> in the iMap call does not export to a vector postscript cleanly
>> (File->Export->'To File'->myFile.eps). Instead of getting a white
>> masked area outside of the map projection, I get black in the eps file.
>> None of the bitmap outputs suffer the same. I've tinkered with the
>> CHANNEL and CLIP_PLANES keywords but was unable to make this go away :(
>
> Sadly, this is pretty much what I would have expected
> in this case. The truth is, the vector implementation
> is just limited when it comes to textured overlays,
> which is what I think this is. :-(
>
I think that is correct. The image uses an alpha channel to mask out the
parts not occupied by real data.
Vector devices don't have depth buffers and have other limitations. Many
do not support alpha, and that's what is happening here. Not all
PostScript versions support alpha. The IDL docs do mention that there are
restrictions and that vector output is most valuable for simpler graphics.
Why are you (Randall) using vector output here anyway? If you are
generating output where image data is covering 100% of the scene, you are
going to end up putting about the same number of bits into the PS file for
bitmap and vector output anyway. So there is no size advantage to using
vector output. In fact, in a case like this one, the vector output file
might be larger because the code to draw the lines and text would have to
be in the file along with the image bits.
Karl
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| Re: Object graphics output police (iImage) [message #44092 is a reply to message #44091] |
Fri, 13 May 2005 08:34 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Randall Skelton writes:
> Can someone explain if there is a way to 'fix' the iTools problem
> demonstrated in the code below. The problem is that the image plotted
> in the iMap call does not export to a vector postscript cleanly
> (File->Export->'To File'->myFile.eps). Instead of getting a white
> masked area outside of the map projection, I get black in the eps file.
> None of the bitmap outputs suffer the same. I've tinkered with the
> CHANNEL and CLIP_PLANES keywords but was unable to make this go away :(
Sadly, this is pretty much what I would have expected
in this case. The truth is, the vector implementation
is just limited when it comes to textured overlays,
which is what I think this is. :-(
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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