[GRASS5] i.composite problems verified

[Eric G. Miller]

On Tue, Apr 17, 2001 at 04:38:51PM -0400, mberglund wrote:
> I have verified that there is a problem on Linux with i.composite.
> 
> I can run i.composite on an image group, and it will run forever, LONG
> after the output has been generated.
> 
> Every thing _seems_ to be ok after you force the software to exit.
> 
> Problems: i.composite will not exit after completeing output.
> 	: continues to consume processesor time after output has been
> completed.
> 
> Any ideas on why this might be?
> 
> I have looked at the generated output in every way I can think of, and
> have seen no errors. It does not seem to be incomplete in anyway.

Looking at a running version of i.composite, I see the gen_colors()
routine near the end calls G_set_color() for the number of color levels
set. This eventually results in a call to add_color_rule() in libgis
(color_rule.c).  Within add_color_rule, there's a loop that iterates
through all of the color rules in order to remove duplicates.  So, as
the number of color levels is increased for i.composite, running time
increases by n^3 or some such.  I suppose it eventually will finish even
for large color rule sets, but there should be no need for the pruning
to begin with.  However, I don't see any color rule function in
color_rule.c that doesn't end up calling add_color_rule().  Maybe we
need some color rule functions that don't check for duplicates?

-- 
Eric G. Miller <egm2 at jps.net>

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