Re: Transparent png plots

From: Rick Brownrigg <brownrig_at_nyahnyahspammersnyahnyah>
Date: Tue Mar 26 2013 - 09:51:35 MDT

Hi Peter,

At present there's no good way to set the background to transparent. For the next release (6.2.0), there will be a new resource -- wkBackgroundOpacityF -- that is intended for just what you are trying to do.

On Mar 25, 2013, at 7:00 PM, Peter Spear <> wrote:

> I am using NCL to make png images to overlay in google maps. I'm showing
> wind strength with colored contours and direction with a vector
> overlay. I would like the png to have variable transparency.
> Specifically I'd like the fills in the contour plot to become
> progressively more opaque for stronger winds.
> The problem I'm having is that I cannot make the base map background
> transparent . The contour fill transparency just lets the base map
> background color show through.
> There is an odd effect that if the transparency of the contour fill
> layer is less than around 0.2, the base layer and contour fill becomes
> completely transparent. This, unfortunately, is not the effect I am
> looking for.
> Is anyone aware of a way to do this?
> Thanks
> Peter
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Received on Tue Mar 26 09:51:44 2013

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