Hi Olver,
> But, I really got a display with just 3 maps, longitude, latuitude and RGB
> like this:
>
> visad.ScalarMap lonMap = new visad.ScalarMap(visad.RealType.Longitude,
> visad.Display.XAxis );
> visad.ScalarMap latMap = new visad.ScalarMap(visad.RealType.Latitude,
> visad.Display.YAxis );
> visad.ScalarMap varMap = new visad.ScalarMap(varRaster,visad.Display.RGB );
>
> where varRaster is a RealType.
>
> The GIFForm has as a range a tuple of 3 componets (R,G,B), and I need
> to convert it to a RealType to put into a map Display.RGB.
>
> There's an example in the P5_09 from the visad's tutorial, but it use 5
> maps.
As described in tutorial section 5.9, a GIF image is read as
a FlatField with MathType:
( (ImageElement, ImageLine) -> (Red, Green, Blue) )
This means that it is a mapping from image line and element to
true-color red, green and blue components. A ScalarMap to RGB
uses psuedo-color when you want to adjust the color map for
a single RealType. You could use a ScalarMap of Red, Green or
Blue to RGB. Or could use ScalarMaps of all three to RGB, to
adjust non-linear mappings for each of Red, Green and Blue.
The domain of a GIF image is defined by simple line and element
coordinates, since GIF images do not include navigation information
for the mapping between (line, element) and (latitude, longitude).
[Note that the McIDAS and HDF-EOS images that VisAD reads do include
such navigation information, but they are much more complex file
formats than GIF.]
If you happen to know the mapping between (line, element) and
(latitude, longitude) for your GIF image, you can extract the
colors values from the FlatField by:
float[][] colors = gif_field.getFloats();
// now colors[0] is an array of red values, colors[1] is an
// array of green values, and colors[2] is an array of blue
// values
and then build a new FlatField with MathType:
((Latitude, Longitude) -> (Red, Green, Blue))
and use a Gridded2DSet for its domain Set, that defines the
(lat, lon) locations of the pixels.
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
