Re: Colour Scaling Control

• To: #TAN TOH FEI# <PA10198510@xxxxxxxxxx>
• Subject: Re: Colour Scaling Control
• From: "From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>" <billh@xxxxxxxxxxxxx>
• Date: Wed, 5 Jul 2000 06:19:54 -0500 (CDT)

> I try to adjust the Scalar mapping for the RGB or IsoContour and having some
> problem in that. As far as I know, the VisAD is using the linear scaling
> method to map the colour for the values. My requirement is for a range of
> figures with negative and positive values, I want to specify a certain
> colour for -ve values, another colour for zero, and different colour again
> for +ve values. On top of that, the linear scaling can be applied for
> individual regions to project a better view. May I know how should I do
> that? Thank you for all who read my emails and response to my mail. Have a
> nice day.

Map colors like this:

  int TABLE_SIZE = 256; // may be whatever you want
  ScalarMap rgbMap = new ScalarMap(yourRealType, Display.RGB);
  display.addMap(rgbMap):
  rgbMap.setRange(lowValueOfRange, hiValueOfRange);
  ColorControl rgbControl = (ColorControl) rgbMap.getControl();
  float [][] table = new float[3][TABLE_SIZE];
  for (int i=0; i<TABLE_SIZE; i++) {
    table[0][i] = // red for i-th value
    table[1][i] = // green for i-th value
    table[2][i] = // blue for i-th value
  }
  rgbControl.setTable(table);

The table values are distributed linearly between lowValueOfRange
and hiValueOfRange, but you can make the table as large as
you like, by adjusting TABLE_SIZE, so the table itself can
approximate any non-linear color mapping.

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

• Follow-Ups:
  • Re: Colour Scaling Control
    • From: Ugo Taddei

• References:
  • Colour Scaling Control
    • From: #TAN TOH FEI#