AVS Modules						          mesh with base
NOAA/ERL/Forecast Systems Laboratory


NAME

	mesh with base - generate a mesh surface with a base from a scalar
	                 1D or 2D field

SUMMARY

	Name		mesh with base

	Type		mapper

	Inputs		field scalar, any-data, any-coordinates
			colormap (optional)

	Outputs		geometry

	Parameters

	    Name		Type		Default		Min Max Choices

	    create mesh		toggle		on
	    z scale factor	float		1.0		unbounded
	    create base		toggle		on
	    base z value	float		-1.0		unbounded
	    base color		integer		-1		-1, 255

DESCRIPTION

	The mesh with base module generates a mesh surface from a field, much
	like field to mesh does.  However, an optional base, or "skirt", can be
	added to the surface to make it appear as a solid, rather than as a
	simple wavy papery surface.  For 1D fields, the surface degenerates to
	a polyline and the base degenerates to a "curtain".  If an optional
	colormap is attached, the surface will be colored according to how the
	field data values map to the colormap, otherwise, the surface will not
	be colored.  Also, the base color may be selected from the colormap.

INPUTS

	Input Field (required, field scalar, any-data, any-coordinates)
		
	    The input data must be a 1D or 2D field of scalar values in 2D or
	    3D space.  Any data type in any grid configuration may be used.

	Input Colormap (optional)

	    If an optional colormap is supplied, the mesh surface will be
	    colored according to how the field data values map to this colormap.
	    The surface base may be left uncolored or colored by one of the 
	    entries in the colormap.

PARAMETERS

	create mesh

	    If the create mesh toggle is set to on, a mesh of the surface
	    defined by the field will be created.  Otherwise, no mesh surface
	    will be created.  Creation of the mesh surface is independent from
	    the creation of the base.

	z scale factor

	    The third dimension of the coordinate system (usually the Z
	    dimension) may be scaled to synchronize with a similar capability
	    found in other modules (like contour field).  A value of zero
	    simply flattens the mesh surface into the Z = 0 plane.

	create base

	    If the create base toggle is set to on, a base around the mesh
	    surface defined by the field will be created.  Otherwise, no mesh
	    surface will be created.  Creation of the base is independent from
	    the creation of the mesh surface.

	base z value

	    The base z value parameter indicates the position of the base in
	    the Z dimension of the field's physical coordinate system.  This
	    value may be below the field minimum, in which case the base 
	    extends below the surface.  It may be above the field maximum, in
	    which case the base extends above the surface.  Or it may be
	    between the field minimum and maximum, in which case the base will
	    be partially below and partially above the surface.

	base color

	    The base color parameter indicates the INDEX of the colormap entry
	    to be used to color the base.  Legitimate values for this index
	    range from 0 through 255.  If the base color value is -1 or no
	    colormap is supplied, the base will not be colored.

OUTPUTS

	Output Geometry

	    If the create mesh toggle is set, the mesh surface will be created
	    as an object named "mesh".  If the create base toggle is set, the
	    base will be created as an object named "mesh base".

EXAMPLE

	This example generates and colors a mesh surface with a base from a
	field.

		                READ FIELD
		                     |
		GENERATE COLORMAP    |
		            |        |
		          MESH WITH BASE
		                |
                         RENDER GEOMETRY
                                |
                          DISPLAY PIXMAP

LIMITATIONS

	Note that for 2D uniform field in 3D space, the Z values are derived
	from the field data values, while for a 2D irregular field in 3D space,
	the Z values are fixed by the field's specified coordinates.

	Even if the input field is uniform, the field origin is always placed
	in the "lower left" corner.  This makes it easy to display uniform and
	irregular fields with the same orientation.

	This module has been used with uniform and "nice" irregular fields.
	It has not been tested with anything really weird.

AUTHOR

	Phil McDonald, NOAA/ERL/Forecast Systems Laboratory


NOAA/ERL/Forecast Systems Laboratory
AVS Modules						          mesh with base