AVS Modules						           file to field
NOAA/ERL/Forecast Systems Laboratory


NAME

	file to field - create a uniform field from an ASCII or binary file

SUMMARY

	Name		file to field

	Type		data input

	Inputs		none

	Outputs		field, any-data, uniform

	Parameters

	    Name		Type		Default		Min Max Choices

	    safety		toggle		on		-
	    file name		browser		$NULL		-
	    file type		radio		-		ascii, bin, vms
	    byte offset		string		"0"		-
	    dimensions		string		$NULL		-
	    data type		radio		-		byte, integer,
								float, double
	    vector length	integer		1		1, unbounded
	    vector order	radio		interlaced	interlaced,
								sequential

DESCRIPTION

	The file to field module creates a uniform field from an ASCII or binary
	file.  The field parameters that are normally contained in the header of
	a field file are specified interactively through the file to field
	parameters.

INPUTS

	None

PARAMETERS

	safety

	    When set, safety serves as a local "disable flow executive" --
	    file to field will not respond to parameter changes until safety
	    is turned on.  This allows the user to set several parameters
	    without having to wait for file to field to respond to each one
	    individually.  When safety is off, file to field will respond to
	    each parameter change as it occurs.

	file name

	    The name of the file to be read is specified through the file name
	    browser.  This file must contain the appropriate number of values
	    (binary or ASCII) in "FORTRAN order" (the same order as the binary
	    section of a field file would).  Vector data may be interlaced or
	    sequential (see vector order).

	file type

	    The file type parameter specifies the type of file that is to be
	    read. Acceptable file types are:

			ascii		ASCII file.

			bin		Local binary file.

			vms		DEC VMS binary file.  Doubles must be
					in VMS "G" format.  Floats and doubles
					are converted to IEEE 754 format.

	byte offset

	    The number of bytes skipped from the beginning of the file is
	    specified through the byte offset parameter.  A string variable
	    is used so that long integer values may be specified.

	dimensions

	    The number of dimensions and their sizes are specified through the
	    the dimensions parameter string.  This string contains ndim integer
	    values separated by blanks.  Each value is the size of one of the
	    computational dimensions of the field.  The number of dimensions
	    is ndim.  The dimensionality of the field's physical space (nspace)
	    will be the same as that of its computational space (ndim).

	data type

	    The data type parameter indicates whether the data are to be 
	    interpreted as byte, integer, float, or double values.

	vector length

	    The field data's vector length is specified through the vector
	    length parameter.

	vector order

	    If the specified file contains vector data, the order of that data
	    be interlaced

			a1, b1, c1, a2, b2, c2, a3, b3, c3, ...

	    or sequential

			a1, a2, a3, ..., b1, b2, b3, ..., c1, c2, c3, ... 

	    The vector order parameter is used to indicate the approprate order.
	    For scalar (vector length = 1) data, the order is of no consequence.

OUTPUTS

	Output Field (any-data, uniform)

	    The output of file to field is a uniform field with the character-
	    istics specified by the user.

EXAMPLE

	This example creates a uniform field from a file and then converts it
	to an irregular field with remap field.  A mesh surface is then created
	from the field.

		          FILE TO FIELD
		                |
		           REMAP FIELD
		                |
		          FIELD TO MESH
		                |
                         RENDER GEOMETRY
                                |
                          DISPLAY PIXMAP

LIMITATIONS

	I plan to add full field parameter capabilities (extents, labels, units,
	etc.) at a later date.

AUTHOR

	Phil McDonald, NOAA/ERL/Forecast Systems Laboratory


NOAA/ERL/Forecast Systems Laboratory
AVS Modules						           file to field