% @(#)plot_pers.hlq	17.1.1.1 (ESO-IPG) 01/25/02 17:43:49 
%++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
%.COPYRIGHT  (c)  1990 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                                               25-APR-1994  RvH
\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 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 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 is 512 by 512 pixels.
\\   
            The X, Y and Z axis can be defined with SET/GRAPHICS
\\
            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.
\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