This module is an extension of the "field_to_polygons" module on AVS 
ftp site.  It allows users to draw columns of the irregular shaded polygon.
For example, users can make a 2 dimensional geographical county map become 3 
dimensional volume using the population of the county as height.  Another
application includes building a house, showing downtown area of a city and
plotting economic data.  The value of the polygo is mapped into color by the 
colormap of AVS.  The input field is a 1D 4 space field with (x,y,z,n,value), 
where (x, y, z) is the coordinate of a vertex in the polygon, n is the number 
of vertices in the polygon, value is the value assign to the polygon. For 
example, a normalized unit square can be define as:

	(-1, -1, 0, 5, 1.0)
	(-1,  1, 0, 5, 1.0)
	( 1,  1, 0, 5, 1.0)
	( 1, -1, 0, 5, 1.0)
	(-1, -1, 0, 5, 1.0)

	Input Data: Field 1-D 4-Space 1-Vector IRREGULAR
                    Colormap (Optional)

	Output data: Geom

	Parameter:

	Number steps:	Number of maximum colors used
	Low data value:	lower color range
	High data value:Higher color range
	INPUT x min:	SW X cornor of the "show box"
	INPUT x max:	NE X cornor of the "show box"
	INPUT y min:	SW Y cornor of the "show box"
	INPUT y max:	NE Y cornor of the "show box"
	Z Scale:	Scale apply to z direction
	Wrap Around:	To specify the "wrap around" of the polygonal volume
	zchoice:	To choice the method for polygonal volume's height
	uniform color:	To set the polygonal volume's color mapping scheme
	Uniform color R:
	Uniform color G:
	Uniform color B:
			To set uniform color for every polygons

	An example network is shown below:

			
				read field
			 	   |
 	generate colormap ----- polygon_column
				   |
				geometry viewer


	Contact person: Jeff Wang, MCNC/NCSC, (919)-248-9242