AVS Modules						        Wide Arrow
U.S. Geological Survey                                          Dec. 1992

NAME
     Wide Arrow  -  create geometry to display a 1D, 2-vector field as a wide 
                    arrow in the X-Y plane
		     
SUMMARY
     Name	   Wide Arrow

     Author	   Evelyn Wright, U.S. Geological Survey 
                                  ew@orpheus.er.usgs.gov
     Type	   mapper

     Input 	   field 1D 2-vector float 3-coordinate irregular

     Output 	   geometry

     Parameter 	   Name         Type     Default      Min           Max
	       Scale Factor     float      1.0   FLOAT_UNBOUND FLOAT_UNBOUND

DESCRIPTION
     Wide Arrow creates the geometry to display a wide arrow indicating 
     vector direction and magnitude at a specified (X,Y,Z) coordinate. 
     The module reads a 1D 3-coordinate irregular field containing a single
     floating-point 2-element vector specifying X and Y velocity components 
     at the (X,Y,Z) coordinate.  

     The length of the wide arrow is proportional to the vector magnitude.  
     The Scale Factor parameter allows the user to scale the data to produce 
     an arrow of the desired length.

APPLICATION
     This module is useful for displaying wind direction and velocity.

INPUT
     The input data must be a 1D 2-vector float 3-coordinate irregular field.
     The vector components are assumed to be in the X and Y directions.

OUTPUT
     The output data is an AVS polytriangle geometry object.

PARAMETER
     Scale Factor
	  This is the multiplicative factor for scaling the data values
          to produce an arrow of the desired length.

EXAMPLE	AVS NETWORK
                            READ FIELD
                                |
	                        |
                            WIDE ARROW
                                |
                                |
                          GEOMETRY VIEWER

ACKNOWLEDGEMENTS
     This module is partially derived from code written by Albert Fischer.