                                                                margin
Chapter 11 Raster Manipulation

The raster margin is a border around the entire raster image of a known, or
specified width.  The margin command may be executed to change the width.  The
margin is important to the edgematching process.  It is the area in which
adjacent map vector data may be displayed.  IMPORTANT NOTE: WHEN THIS COMMAND
IS INVOKED AGAINST AN ASSEMBLED OR ATTRIBUTED MAP FILE, ALL VECTORIZATION
AND/OR ATTRIBUTES WILL BE LOST.  THE MAP WILL REQUIRE RE-ASSEMBLY AND
RE-ATTRIBUTING.  THE REGISTRATION WILL NOT BE LOST.

Note also that if a b-raster (original scan) exists, it will be replaced 
automatically by a copy of the (new sized) editable raster.  This is necessary 
because the raster sizes need to be identical.

If a map is imported as a raster (i.e. scan file), with pre-determined raster
dimensions, the margin is created when the raster corners are identified
(register raster); it is the raster area exterior to a rectanglular envelope
containing the four raster corners.  If a map is first registered geodetically
(lat/lon, utm or state plane registration) and is not an imported raster file
with pre-determined raster dimensions, the margin width is calculated to be 10%
of the overall map width and the margin area is presumed to be the raster area
exterior to a rectangular envelope containing the four map corners.

margin

    Sets the raster margin to a specified pixel width.

         margin w

    Forces the raster margin to a specified minimum pixel width which may be
    more or less than the current margin width.
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    Options/arguments:

         w         Positive integer of margin width in pixels
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    Example(s):

    To set the margin width to 20 pixels, enter:

         margin 20
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    See also:

              erase_margin
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