[ncl-talk] Fwd: Pennants wind barbs thickness

Rabah Hachelaf hachelaf at sca.uqam.ca
Thu Jul 24 13:29:43 MDT 2014

Hi Kyle,

My goal is overlay a green windbarb over a black ones with a higher
thickness to get a green barb with a black borders like image attached.
I success to do that but for winds speed over 50KT the problem about
pennant occur.

Please can you tell me what is steps to do to create a filled polygone and
rotated it to the angle of each wind barb line.


2014-07-24 15:13 GMT-04:00 Kyle Griffin <ksgriffin2 at wisc.edu>:

> As Dave is one of the developers, he does usually know best. However, if
> it is very important to you to change it and you have a reasonable number
> on your plot, I would recommend outputting your file as a PS, EPS, or PDF
> and taking the vector file into a post-processing program such as Adobe
> Illustrator or similar. There, you can edit the length/width/color/position
> of the lines as necessary. Beyond that, I doubt this feature is simple to
> address. If you were going to set about fixing this as a user, you could
> start writing the code to draw each line individually relative to a base
> point and use the gsn_add_polyline(...) function or similar to try and
> construct these on your own. For the pennants, you would likely need
> gsn_add_polygon(...) to create a filled polygon, once again rotated to the
> angle of each wind barb line. Of course, this would be duplicating much of
> the code already written behind-the-scenes in NCL, but it IS possible if
> you really need a customized implementation in the immediate future.
> Kyle
> ----------------------------------------
> Kyle S. Griffin
> Department of Atmospheric and Oceanic Sciences
> University of Wisconsin - Madison
> Room 1421
> 1225 W Dayton St, Madison, WI 53706
> Email: ksgriffin2 at wisc.edu
> On Thu, Jul 24, 2014 at 1:50 PM, Rabah Hachelaf <hachelaf at sca.uqam.ca>
> wrote:
>> Hi David,
>> Yes i re-post my question maybe some one from NCL users has an other idea.
>> Rabah
>> 2014-07-24 14:11 GMT-04:00 David Brown <dbrown at ucar.edu>:
>> Hi Rabah,
>>> As you know I previously answered this question for you personally prior
>>> to your joining ncl-talk. For the record I am now answering on ncl-talk:
>>> You have diagnosed the problem correctly, and unfortunately there is no
>>> resource to directly control the size of the pennant part of the wind barb
>>> glyphs. The size and area of the pennants is fully determined by
>>> the vcWindBarbTickLengthF and the vcWindBarbTickAngleF. Unfortunately there
>>> is currently no adjustment made to account for the width of the lines,
>>> which also has the effect of making the barbs longer than their nominal
>>> length. No one has ever asked for this kind of flexibility in the past, but
>>> I can see that it could be useful.
>>> You could try playing with the tick length and tick angle resources.
>>> They may help give you a combination that looks better. But until we can
>>> add another option, my suggestion would be to just try to keep the width as
>>> small as feasible for your purposes.
>>>  -dave
>>> On Tue, Jul 22, 2014 at 4:54 PM, Rabah Hachelaf <hachelaf at sca.uqam.ca>
>>> wrote:
>>>> Hi NCL users,
>>>> I have problem with plotting wind barb with a relatively big thickness
>>>> I am using vcWindBarbLineThicknessF command to increase wind barb
>>>> thickness
>>>> it's correct for all wind barbs only for higher than 50KT ones where
>>>> the pennants or small triangle aren't affected by the thickness set.
>>>> When reading some documentation i noted that
>>>>   " The pennants are drawn using a filled polygon, while the ticks,
>>>> the shaft, and the calm circle are all rendered with polylines."
>>>> So i think this is why pennants aren't affected by the thickness change.
>>>> Have you some tricks to solve this problem and get the same pennants
>>>> thickness like the ticks.
>>>> Attached you can find an example of my case, where wind speed is
>>>> supposed to be about between 55KT and 60KT
>>>> Thank you.
>>>> ------------------------------
>>>> Cordialement,
>>>> Best regards,
>>>> Rabah Hachelaf
>>>> Msc Studient UQAM
>>>> Montréal/CANADA
>>>>      ____
>>>>     (       )
>>>>    (        )
>>>>   (___ __)
>>>>    /////////
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>> --
>> ------------------------------
>> Cordialement,
>> Best regards,
>> Rabah Hachelaf
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Best regards,
Rabah Hachelaf
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