Re: 2d color table in VisAD

Hi Marcel,

I'm CC'ing the list because your question is of general
interest, and because technical questions should come to
visad-list.

The solution to Jay's problem was to use true color (with
three RealTypes mapped to Red, Green and Blue in the
display). A 2-D color table is really a pseudo color
technique. You could actually implement a true 2-D color
table for pseudo color, by defining two DisplayRealTypes
for the table indices, and a custom DataRenderer that
knows how to render them (including looking up colors in
a 2-D analog of ColorControl).

However, a much easier approach would be to define a
CellImpl whose doAction() method transforms a Data
object with MathType:

  (domain -> (index1, index2))

into a data object with MathType:

  (domain -> (r, g, b))

where domain may have any dimension, and there are
ScalarMaps of r, g and b to Red, Green and Blue. Of course,
values of index1 and index2 would be used as indices into
the 2-D color table. The CellImpl could include methods
for setting the table. The CellImpl would pass its output
data to the setData() method of a DataReference, which
would be linked to your DisplayImpl. The input data would
come from a second DataReference, linked to the CellImpl
via its adReference() method.

Good luck,
Bill

On Fri, 7 Mar 2003, Marcel Schmittfull wrote:

> Hi,
>
> I'd like to implement a 2d color table (see f.e.
> http://www.uni-graz.at/imawww/vqm/images/complexplane.jpeg)
> in my visad program. I guess, there's an analogy to your
> topic "Color Gridded3DSets" in visad's mailinglist.
> Could you send me your solution code of your problem,
> please ? This would probably really help
>
>
>
> Viele Gre
> Marcel
> --
> mailto:marcel-sl@xxxxxx
> http://www.schulphysik.de/japtik/
>
>