%  @(#)overplvect.hlq	17.1.1.1 (ESO-IPG) 01/25/02 17:43:48
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1990 European Southern Observatory
%.IDENT      overplvect.hlq
%.AUTHOR     RHW, IPG/ESO
%.KEYWORDS   MIDAS, help files,OVERPL/VECTOR
%.PURPOSE    On-line help file for the command: OVERPL/VECTOR
%.VERSION    900812 RHW Implementation
%----------------------------------------------------------------
\se
SECTION./VECT
\es\co
OVERPLOT/VECTOR                                                 26-AUG-1991 RHW
\oc\su
OVERPLOT/VECTOR fram_a fram_b [coord_str] [scale_r] [pos_range] [sm_par] [head]
	overplot vector map from two 2-dim. images with smoothing option
\us\pu
Purpose:
             Overplot vector map from two 2-dim. images with smoothing option
\up\sy
Syntax:      OVERPL/VECTOR fram_a fram_b [coord_str] [scale_r] [pos_range]
                           [sm_par] [head]
\ys\pa
             fram_a    = input frame containing the intensities
\ap\pa
             fram_b    = input frame containing the position angles
\ap\pa
             coord_str = area to be plotted in standard MIDAS notation; see 
                         MIDAS Users Guide Chapter 3. Default is either the 
                         manual setting done with by the SET/GRAPHICS 
                         command (is present), or the whole area.
\ap\pa
             scale_r   = scale of the vector length in intensity units/mm. By
                         default the command computes the average of the 
                         minimimum and maximum cut values in the descriptor of
                         frame_a; this average intensity will correspond with a
                         vector length of 10 mm.
\ap\pa
             pos_range = range of positions angle to be plotted in degrees. 
                         Default is 0,360. The position angle is defined using 
                         the standard astronomical convention: 0 is pointing
                         to the top, and the angle increases counter-clockwise.
\ap\pa
             sm_par    = smoothing parameter i.e. box width in pixels;
                         default is 1
\ap\pa
             head      = head parameter. If the vector should have an arrow at
                         its end this parameters should be 1, else give a 0.
                         Default is 1, i.e. the arrow is drawn.
\ap\no
Note:        The coordinates for the area are optional. If one specifies a "?",
             the area will be take for the manual frame settings for the x-
             and y-axis. If "C" is given, the window is selected interactively
             on the display screen using the cursor facilities. The cursor will
             be set on automatically, if it is not already. To pick up the
             coordinates, switch the cursors ON and press ENTER. To exit,
             switch the cursors OFF and press ENTER.
\\ 
             After the overplot the last (over)plotted data set is the active
             one and subsequent commands will work on these data.
\on\see
See also:
             PLOT/VECTOR, SHOW/GRAPHICS, SET/GRAPHICS, PLOT/AXES, 
             PLOT/CONTOUR, OVERPLOT/CONTOUR, PLOT/GRAY, OVERPLOT/GRAY
\ees\exs
Examples:
\ex
             PLOT/AXES 100,400,100,50 100,400,100,25 ? 
             OVERPL/VECT spir_i spir_p [@281,@281:@320,@320] 0.5 ? 3
             Overplot the polarisation vector using the intensities from spir_i
             and the position angle information form spir_p. Use a scale of 
             0.5 units/mm for the size of the vectors (i.e. an intensity of 
             10 pixel units will make the vector 20 mm). Apply a box smooth 
             over 3x3 pixels.
\xe \sxe