Hi Andrew,
> Hi there,
>
> I've got some radar data in my visad display, which I am overlaying
> over a filled in map and some other stuff. The radar data is from
> a McIDAS ADDE image server.
>
> The bad bit is that a large black box surrounds the small amounts
> of rain (radar data).
> So what I want to do is set 0 values in the radar data to be
> transparent.
> This is something along the lines of mapping radarValue to ALPHA,
> but not quite, as I don't want a linear relationship.. I want to
> define my own function (in loose language). This seems to be
> possible with mapping samples to colours, where you get your mouse
> and choose the R, G and B intensities for that sample, on a
> contiguous sample space thingy.
> Can I do this for alpha? How do I do it programatically? I don't
> want the user having to drag his mouse around just to set 'no rain'
> to be transparent.
>
> thanks in advance,
Though I'm sure Bill's approach would work, you might considering
setting the 0 values to Float.NaN (Not-a-number).
This would make them invisible (or transparent, I'm not sure).
Cheers,
Ugo
