Hi Andrew,
> 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.
You can do it with a ScalarMap to Display.RGBA. The
getControl() method for this ScalarMap will return a
ColorAlphaControl, and you can call its setTable() method
to set the 4-component lookup table for red, green, blue
and alpha. See Sections 4.6 and 4.11 of the tutorial for
more details.
Cheers,
Bill
----------------------------------------------------------
Bill Hibbard, SSEC, 1225 W. Dayton St., Madison, WI 53706
hibbard@xxxxxxxxxxxxxxxxx 608-263-4427 fax: 608-263-6738
http://www.ssec.wisc.edu/~billh/vis.html
