
@C1@c@b@_ Place Marks

     To place marks, defined as simple geometric figures(sgf), into an
     image at locations addressable either by pixels or by some user 
     defined coordinates units.

@b Interactions
   An sgf is selected by clicking the mouse on the appropriate bitmaps
   shown on top of the control panel. Upon its selection, the bitmap
   is drawn in the main window with currently selected attributes,
   including color, size and line width etc.

   To move the mark, simply click the mouse in the main window where
   you want the object to be or by typing the new locations into the input
   field labeled X and/or Y.

   For precise placement or sizing of the sgf, keyboard arrow keys and 
   ijkl (as in VI(1)) and XxYy can be used. [1-9] controls the step size.
   
   All objects are designed with an aspect ratio of 1. To change aspect ratio,
   turning off the KeepAsp button and scale x and y independently.  
   (this is how to get a rectangle from a square or an ellipses from a circle).

   To change the orientation of the object, click mouse on Rotate button
   or by typing rR (r counter-clockwise and R clockwise). [1-9] controls
   the step size in degrees.

   To place the sgf into the image, press the OK button in the control panel.
   
   Note that there are two modes of operation: one is the immediate mode
   in which upon pressing the OK button, the sgf is rendered directly into
   the raster and the other is the deferred mode in which the sgf is saved
   as a separate entity with full vector information. The deferred mode is
   useful when a hardcopy is desired, for example, via PostScript, because
   full vector info will be used to rendered the sgf on the printer which
   typically has better a resolution than the screen.

   All lines are drawn anti-aliased using linesmooth and blendfunction
   primitives if hardware is capable. Anti-aliasing is not performed if
   the image in not in RGB mode or the line width is not 1. To turn
   off anti-aliasing, See SmoothLines flag in Setup dialog or the man page.

   Anti-aliasing is performed at the final rendering stage (that is after
   pressing the OK button), thus what you see while moving the marks is not
   as good as what you will get.

   To toggle the mode of operation, press mouse on Immediate/Deferred
   button.

   If all marks are rendered in deferred mode and later on, there is
   a need to render these into raster, you can do a crop following
   marking.

@b Coordinate Systems
   By default, the coordinate units are pixels with the origin at the 
   lower-left corner of the image. To switch to user defined coordinate
   system, click the mouse on the round button labeled user/pixel. The
   mapping between the user coordinates and pixels can be changed by 
   inputting the mapping coefficient, defined as the ratio between 1 unit in
   the pixel coordinate system and the value it represents in the new
   system, in fields labeled MX and MY. For example, if 1 pixel-pixel
   distance represents 2.1 miles, you would enter 0.476, that is 1/2.1.
   Then all requests should be made in this new units, such as moving
   the sgf 10 miles west etc.

   To move the origin, press the button labeled SetOrigin, the location
   where the object currently is will become the origin.

@b Reporting
   For speed reasons, only the x- and y- components are reported by
   default. To get the distance from the origin, (sqrt(x*x + y*y), turn
   on the Dreport option.

@b Note
   In Immediate mode, rendering outside the image is clipped. To
   render an sgf outside the image, do it in deferred mode and then
   do a crop with proper filling. Or enlarge the image using crop
   first, then render the marks.

   If for whatever reason you want to turn off anti-aliasing, use
   the Setup entry SmoothLines.
