Transparent png plots

From: Peter Spear <peter_spear_at_nyahnyahspammersnyahnyah>
Date: Mon Mar 25 2013 - 19:00:45 MDT

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 Mon Mar 25 19:01:02 2013

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