| Re: cyclic colour tables? [message #32169] |
Mon, 23 September 2002 08:49  |
Manish
Messages: 20
Registered: April 2001
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Junior Member |
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Cheers David,
This may be a bit of a daft question, but how do i get around the limit of
60 elements in the LEVELS keyword for contour? I assume if i could set this
high enough (ie a lot greater than 60) then i would have the resolution i
need and the colours would cycle automatically (through C_COLORS right?),
but it won't let me go above 60... :-(
I fear i am but a blind minnow in the ocean that is IDL, and your help is
very much appreciated!
Cheers,
Manish
--
"David Fanning" <david@dfanning.com> wrote in message
news:MPG.17f8dd98b727081a9899ba@news.frii.com...
> M (mrmanish@bigfoot.com) writes:
>
>> I have a contour map (of solar radiation, longitude-latitude type) and
i've
>> set up the routine to give a nice colour contour plot... I just wanted
to
>> know if it is possible to pick out small variations using a colour
table -
>> the maximum (solar radiation) value is around 50, but i would like to
>> highlight areas where the variation is only around 2 % or less maybe....
>>
>> Is there a way to cycle colour tables, so that fine structure in the
contour
>> plot can be seen?
>
> If you are using a 24-bit graphics card you can pretty much
> do whatever you like with colors. The NOERASE keyword might
> also come in handy. :-)
>
> 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: cyclic colour tables? [message #32265 is a reply to message #32169] |
Mon, 23 September 2002 09:23  |
James Kuyper
Messages: 425
Registered: March 2000
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Senior Member |
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M wrote:
>
> Cheers David,
> This may be a bit of a daft question, but how do i get around the limit of
> 60 elements in the LEVELS keyword for contour? I assume if i could set this
> high enough (ie a lot greater than 60) then i would have the resolution i
> need and the colours would cycle automatically (through C_COLORS right?),
> but it won't let me go above 60... :-(
Are you sure that contours are the right approach? Much more than 60
different contours is going to be very hard to follow by eye. If you
want to use that many different discrete levels, you might be better off
converting your raw data into discrete integer levels:
discrete_date = FIX( (continuos_data+offset)/bin_size )
and just displaying it directly, rather than trying to draw the lines
seperating the levels. If your array is too small to make decent 'tv'
output, you might want to rebin it (before discretizing it, not after).
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| Re: cyclic colour tables? [message #32267 is a reply to message #32169] |
Mon, 23 September 2002 09:02 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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M (mrmanish@bigfoot.com) writes:
> This may be a bit of a daft question, but how do i get around the limit of
> 60 elements in the LEVELS keyword for contour? I assume if i could set this
> high enough (ie a lot greater than 60) then i would have the resolution i
> need and the colours would cycle automatically (through C_COLORS right?),
> but it won't let me go above 60... :-(
Well, now. That's where that NOERASE keyword might be
*very* useful! :-)
I'd draw the contours in groups of 60 or so, taking
care not to erase the display between calls to the
Contour command.
> I fear i am but a blind minnow in the ocean that is IDL, and your help is
> very much appreciated!
We are *all* minnows, more or less.
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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