AVS Modules						   field to contour
Lawrence Berkeley Laboratory					14 Dec 1992

NAME
	field to contour

SUMMARY
	Name	field to contour
	Type	mapper
	Inputs	colormap (REQUIRED)
		field 2d any coordinates, scalar, float (REQUIRED)
	Output	geometry

	Parameters
	Name			Type		Default	Min	Max
	Level			float		0.0	unbounded
	2D Z coord control	choice		z=0.	z=0.,
							z=field data

DESCRIPTION
 	The field to contour routine creates colored contour lines 
	around regions in which the threshold specified by the "level"
	parameter is crossed.  The module can process only 2d
	datasets, but these may exist in 3-space (if the field
	is irregular) or in 2-space (rectilinear or uniform).
	
	The algorithm used is a subset of the more familiar 3d
	marching cubes algorithm.

	Dec 1992 Modifications

	For 2space fields (all 2d rectilinear and uniform fields), the
	user may elect to have the z coordinates in the output geometry
	set to a constant (0.0 in this case, an arbitrary constant in
	a later release) or to be set to the field data value.


	Feb 1994 Modifications

    Enhancements include:
      1. Generating contours as polylines and not disjoint lines
         for faster rendering;
      2. Generating whole range of contours by a single module;
      3. Generating surfaces (these produced by field_to_mesh
         do not fit into dimensions, sometime);
      4. Optional plane and/or 3D maps;
      5. Second field and colormap input to color surfaces.

    Updated by:
      Krzysztof (Chris) S. Nowinski
      Institute of Applied Mathematics and Mechanics
      Warsaw University
      know@helium.appli.mimuw.edu.pl
      2/94


INPUTS	
	Data Field (required; field 2D scalar float any-coordinates)
	
	AVS Colormap (required)
	The color of the lines produced by this module is determined
	by doing a lookup into the input colortable.  The user specifies
	the mapping from the field scalar space into colorspace through
	the use of the colormap.

PARAMETERS

	Level (float)
	This floating point value indicates the threshold level
	to use in generating contour lines.

	Z Coordinate Control
	Used to select whether to set the output Z coordinates to a
	constant, or to the values in the input field.

OUTPUTS
	AVS geometry.

EXAMPLE

	 generate colormap	read field  (read the bluntfin dataset)
		|		    |	
	   	|            orthogonal slicer
		|		    |
		|      +------------+
                |      |
	     field to contour
		   |
	     geometry viewer

RELATED MODULES
	contour to geom

AUTHOR
	Wes Bethel, Lawrence Berkeley Laboratory

AVS Modules						       field to contour
Lawrence Berkeley Laboratory					   14 Dec 1992