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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Thanks Rick, that worked (see attached plot, showing Antarctic sea ice in white over ocean temperature, where the opacity represents sea ice concentration)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Initially I couldn’t get it to recognise the ‘a’ in the RGBa colormap – I was using RasterFill as my fill mode (since this is a highres model it’s a bit quicker). It worked when I changed to AreaFill<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I’m using version 6.6.2, so according to the documentation for cnFillMode, RasterFill ‘should’ support transparency, so maybe some clarification on the docs is needed.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Thanks again<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Will<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:12.0pt;color:black">From: </span></b><span style="font-size:12.0pt;color:black">Rick Brownrigg <brownrig@ucar.edu><br>
<b>Date: </b>Thursday, 25 March 2021 at 11:58 pm<br>
<b>To: </b>Will Hobbs <will.hobbs@utas.edu.au><br>
<b>Cc: </b>"ncl-talk@mailman.ucar.edu" <ncl-talk@mailman.ucar.edu><br>
<b>Subject: </b>Re: [ncl-talk] question about contour opacities<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hi Will,<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Offhand, I would think you could set up a custom colormap that consisted of RGBa tuples, which were all the same value for the 1st 3 components, and only the opacity (alpha) channel varied. Something like:<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> myColors = new((/100,4/_, float) ; colormap of 100 values<o:p></o:p></p>
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<p class="MsoNormal"> do i=0,99<o:p></o:p></p>
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<p class="MsoNormal"> mColors(i,:) = (/ 0., 0., 1., i / 100. /) ;; transparent to solid blues<o:p></o:p></p>
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<p class="MsoNormal"> end do<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Then set either cnFillPalette or cnFillColors to "myColors"<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> <a href="http://ncl.ucar.edu/Applications/rgbacolor.shtml">
http://ncl.ucar.edu/Applications/rgbacolor.shtml</a><o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">Hope that helps...<o:p></o:p></p>
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<p class="MsoNormal">Rick<o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal">On Thu, Mar 25, 2021 at 12:43 AM Will Hobbs via ncl-talk <<a href="mailto:ncl-talk@mailman.ucar.edu">ncl-talk@mailman.ucar.edu</a>> wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Hi all<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I suspect the answer is ‘no’, but is it possible to set multiple values for cnFillOpacity?<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I’d like to plot an overlay that has a single fill color, but uses opacity as it’s ‘colourmap/contour level’.
<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">I can see a way of doing this by looping through each contour level and setting explicit levels/opacities each time, but I wonder if there’s a more efficient way.<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto">Will<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><b><span style="color:black">Will Hobbs
</span></b><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black"> </span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">Institute for Marine and Antarctic Studies (IMAS)<br>
University of Tasmania</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">Private Bag 80, Hobart, 7001</span><span style="color:black">, TAS,
</span><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">AUSTRALIA</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black">+61 3 6226 2970</span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><a name="m_9199237565650479618__Hlk40780175"></a><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#E42313"><a href="http://imas.utas.edu.au" target="_blank" title="http://imas.utas.edu.au/"><span style="color:#0563C1">imas.utas.edu.au</span></a></span><o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:black"><a href="https://aappartnership.org.au" target="_blank" title="https://aappartnership.org.au/"><span style="color:#0563C1">aappartnership.org.au</span></a></span><o:p></o:p></p>
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<p class="MsoNormal" style="mso-margin-top-alt:auto;mso-margin-bottom-alt:auto"> <o:p></o:p></p>
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