%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1990-2008 European Southern Observatory
%.IDENT      plot_pers.hlq
%.AUTHOR     RHW, IPG/ESO
%.KEYWORDS   MIDAS, help files, PLOT/PERSPECTIVE
%.PURPOSE    On-line help file for the command: PLOT/PERSPECTIVE
%.VERSION    1.0  900717 RHW creation
%.VERSION    1.1  910322 RHW changes acc. to verification form
%.VERSION    1.2  940425 RvH updated the documentation
%----------------------------------------------------------------
\se
SECTION./PERS
\es\co
PLOT/PERSPECTIVE                                         06-MAR-2008 RHW,KB
\oc\su
PLOT/PERSPECTIVE frame [coord_str] [alt,azi] [scal,offs] [sm_par] [xy_flag]
	tree dim. representation of a 2-dim. frame, with smoothing option
\us\pu
Purpose:    
            Plot 3 dim. representation of a 2 dim. image, with smoothing option
\up\sy
Syntax:     
            PLOT/PERSPECTIVE frame [coord_str] [alt,azi]] [scal,offs] [sm_par] 
                             [xy_flag]
\ys\pa
            frame = name of image file
\ap\pa
            coord_str = area to be plotted in standard MIDAS notation; 
                 see MIDAS Users Guide Chapter 3. Default is the manual setting
                 done with the command SET/GRAPHICS (if present), or the whole
                 area (see note below)
\ap\pa
            alt,azi = viewing angles altitude (angle above the plane of the 
                 plot: alt=0 is edge-on; alt=90 is face-on) and azimuth 
                 (angle in the plane: azi=0 for the x-axis horizontally at the 
                 lower part of the plot; azi=90 for the y-axis horizontally at
                 the lower part). Default is 45,30
\ap\pa
            scal,offs = scale and offset parameters. The scale controls the 
                 height coordinate (ZAXIS) with respect to the graphics area. 
                 The plot will (by default) fill the graphics area (-> scale 
                 = 1). Scale = 0.5 will make the zaxis half of its default 
                 size. 
                 The offset control controls the offset of the data in the 
                 z-direction (NOT of the axes). The default is 0. 
\ap\pa
            sm_par = smoothing parameter i.e. the number of pixels "around" the
                 central pixel which define the neighbourhood of that pixel. 
 
                 Total number of pixels is then: (2*sm_par + 1)**2 
                 Only integer numbers are allowed. Default is 0
\ap\pa
            xy_flag = flag to indicate which lines should be drawn:
                 "X" the x-direction only, "Y" the y-direction only, and "XY"
                 both the x- and y-direction (default)
\ap\no
Note:       
            The max. length of image file names for plotting is 60 chars.
               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 a "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.
               The maximum area that can be plotted in a perspective
            view is 512 by 512 pixels.
               In plot mode 1 and 2 (see SET/GRAPHICS) a coordinate frame is 
            plotted around the 3-dim view at the level of the minimum and 
            maximum found in the frame used.
               PLOT/PERSEPTIVE has some difficulties drawing almost vertical 
            lines (bottom to top), i.e. the surface is often not closed very 
            nicely.
            By plotting only the horizontal lines (using the xy_flag) you will
            get a nice results. The xy_flag is also very useful if you are
            plotting more then 100 lines.
               The X, Y and Z axis can be defined with SET/GRAPHICS
\on\see
See also:   
            PLOT/CONTOUR, SET/GRAPHICS, SHOW/GRAPHICS
\ees\exs
Examples:
\ex
            plot/perspec spiral [@200,@200:@400,@400] 
              Make a perspective plot of the frame spiral, using the default
              viewing angles. 
\xe\ex
            plot/perspec spiral [@200,@200:@400,@400] 25,230 .2,-1 2 x 
              The same image as before but the image will be seen under 
              different viewing angles, the intensity is scaled down by a 
              factor 5, with an offset of -1, the data is smoothed by taking a 
              box of 5 pixels around each pixel, and only the x lines are shown.
\xe \sxe
