Re: contour smoothing

From: Adam Phillips <asphilli_at_nyahnyahspammersnyahnyah>
Date: Fri Oct 30 2009 - 14:09:10 MDT

Hi Dave,
For what it's worth I'd stick with the webpage advice and just do
multiple passes on the data.

David B. Reusch wrote:
> Yes, that does seem to be helping, though I have to apply it three times
> to get where I want to be (with p=0.5, q=0.25, so fairly "heavy"
> smoothing). Is there any more guidance out there for the smoothing
> parameters? For example, is it worth trying different values of p or
> should I just stick with the web page advice and do multiple passes? I
> tried finding the source code so I could evaluate this myself, but
> didn't have any luck (and I do a binary install anyway so I might not
> even have it!).
> For what it's worth, I'm still curious about what I wasn't seeing with
> cnSmoothingTension -- but smth9 seems to meet my needs.
> Thanks,
> Dave
> Adam Phillips said the following on 10/30/09 3:20 PM:
>> Hi Dave,
>> I would highly recommend using smth9_Wrap to smooth your data before
>> plotting. This allows you to have complete control over the amount of
>> smoothing (heavy, light, pass the data through the function a few
>> times), as opposed to trying to mess with the cnSmoothingTension resource.
>> Adam
>> David B. Reusch wrote:
>>> Hello,
>>> I have a long-time-working script that uses gsn_csm_contour_map_polar to
>>> produce panelled plots of Antarctic meteo data and I've been wanting to
>>> experiment with tweaking the contouring so that basically I get a
>>> "smoother" look (for example, get rid of any really small areas that
>>> aren't particularly representative of the larger picture). Rather than
>>> approaching this by changing the cmin/cmax/cint values (which might also
>>> work, I think), I've been trying to use the cnSmoothingOn and
>>> cnSmoothingTensionF resources. The reason I'm writing is that these
>>> don't appear to be doing anything! I've tried a wide range of tension
>>> values with no resulting plot changes. All I've done to the script is
>>> add these two resources -- am I missing something else I need to get
>>> this to work? I didn't see any examples that address these particular
>>> resources (though I know there can't be examples for everything).
>>> I can provide the script/data if needed (I didn't attach the script
>>> because it's *long* and ugly). Or if someone has an example, that would
>>> be great. Also, if the prevailing wisdom is to use cmin/cmax/cint to
>>> accomplish such smoothing, that would be really nice to know too!
>>> This is NCL 5.1.1 on Mac 10.5.8.
>>> Thanks,
>>> Dave Reusch
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Adam Phillips
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Climate and Global Dynamics Division         fax: (303) 497-1333
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Received on Fri Oct 30 14:08:58 2009

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