Re: Map projections

• To: visad-list@xxxxxxxxxxxxx
• Subject: Re: Map projections
• From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>
• Date: Mon, 28 Jun 1999 10:56:31 -0500

Hi Hank,

A good example of VisAD CoordinateSystems is satellite image
navigation in examples/SatDisplay.java.  This application
reads McIDAS satellite images file using the AreaAdapter
class.  These images have MathType:

  ((ImageElement, ImageLine) -> (Band0, ..., Bandn))

where (ImageElement, ImageLine) has a CoordinateSystem with
reference (Longitude, Latitude).  The image is displayed
using the ScalarMaps:

  Latitude -> Display.Latitude
  Longitude -> Display.Longitude
  Band0 -> RGB

In other words, the CoordinateSystem carries the satellite
navigation information which is used to geo-locate the image
in the display.

Another interesting application is examples/HSVDisplay.java.
It displays a Set with MathType:

  SetType(hue, saturation, value)

where (hue, saturation, value) has the HSVCoordinateSystem
with reference (red, green, blue).  This Set is displayed
using the ScalarMaps:

  red -> XAxis
  green -> YAxis
  blue -> ZAxis
  hue -> Hue
  saturation -> Saturation
  value -> Value
  hue -> IsoContour
  saturation -> IsoContour
  value -> IsoContour

This is a neat example of using a color coordinate system
in spatial mappings, in order to visualize the geometry of
color spaces.

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