
                               MAP SELECTION


The "Map Selection" window specifies the geographic area for frames  
in a loop.  Map overlays and their associated attributes are also selected
in this window.  The "Map Selection" window is invoked by clicking the "MAP" 
button in the main NMAP window or in the "Data Selection Window".

Several methods are available to select a geographic area.  Click on one
of the buttons along the left side of the GUI to select a pre-defined
geographic area.  The pre-defined areas listed in the GUI are obtained
from the table: $GEMTBL/nmap/mapinfo.tbl.  Different areas may be specified 
by editing the contents of this table.  A pre-defined area is any valid
GEMPAK GAREA that is defined in the table $GEMTBL/stns/geog.tbl.
Note that the first entry in the mapinfo.tbl, which appears as the top entry in 
the GUI, is the default geographic area when NMAP is invoked.  The geographic 
region may be interactively defined by clicking on the "Custom" button to 
specify the lat/lon bounds and map projection.  See the help on "Customized 
Maps" for additional details. 

A geographic area may be defined by zooming on the map window.  Click the
"Zoom" button to define the corner points of the zoomed region.  Click the
left mouse button to define the first corner point.  Then hold the mouse
button down and drag the mouse to shape the zoom box.  Release the left
mouse button to complete the zoom box definition.  This action will immediately
zoom the area.  Two types of zoom are available.  The extended zoom option
(the default) attempts to fill the entire display area.  It uses either the
width or height of the zoom box to define the zoom area and fills the window
appropriately.  The non-extended zoom option uses the corner points of the
zoom box to exactly define the zoom area, which may not necessarily fill 
the display area.  The extended zoom option is turned on/off by selecting it 
under the "Option" pulldown in the main NMAP window.

When the selected data includes satellite or radar imagery, the last image 
in the loop can be displayed in the "Map Selection" window so that a region 
of interest may be chosen with the aid of the image.  Click on the 
"Show Image" button to display the image in the GUI.  The image projection 
is always used for the selected geographic area when a data source is a 
radar or satellite image.  As a result, geographic areas located far from the 
region covered by the image may not be viewable.   

Click on the buttons located under the "Overlays" title on the right side of
the GUI, to select desired map overlays.  Overlays can be either geographic
boundaries, e.g., rivers, defined by GEMPAK map files, or markers, e.g., 
WFO locations, defined by GEMPAK station files.  Click on the overlay name 
button to change the attributes associated with the overlay.  Click the button 
located to the left of the "Zoom" button to preview all selected map overlays.
Changing the attributes of an overlay will also display that overlay as a 
preview.  The overlays and their default attributes, e.g., color, are 
specified in the table: $GEMTBL/nmap/mapovl.nmap.  The mapovl.nmap table
also contains a column that controls which overlays are turned on by
default when NMAP is initiated.  This table may be edited to change the 
overlays and the defaults.  See the table for additional details.   

Map settings including the base map, zoom area, overlay selections, and
roam factor can be shared among loops by clicking on the "Apply Map Settings"
or "Get Map Settings" buttons.  

Click the "Apply Map Settings" button to apply the map settings of the 
current loop to other loops.  This button is useful for applying map settings
before data is loaded into loops.  For example suppose that the same
zoom area is desired for loop 1, 2 and 3.  Loop 1 has a 
visible satellite sector, loop 2 has an infrared sector and loop 3 
has model data ready for loading using a Stored Procedure File (SPF) or manual
selections.  Zoom on loop 1 to get the desired area of interest by 
clicking the "Zoom" button in the "Map Selection" Window.  Then click the
"Apply Map Settings" button to apply the zoom area to loops 2 and 3.  Clicking 
the "Load" button will then load all loops with the same zoom area. 
 
Click the "Get Map Settings" button to acquire the map settings from a 
particular loop for the current loop.  This button is useful for loading data 
after map settings have been applied to loaded loops.  For example, suppose 
loops 1 and 2 have already been loaded with a common zoom area applied and that 
this loop area is desired for new data to be loaded in loop 3.  After selecting
the data to be loaded using the "Data Selection Window", click the "Map" button.
Then click the "Get Map Settings" button.  Select loop 1 or 2 in the GUI and
click the "Accept" button.  The zoom area for loop 3 will match the area for
loops 1 and 2 upon loading.

NMAP always loads images using the projection associated with the image file.
Therefore, applying settings between loops that contain images obeys the 
following rules.  If the destination loop contains an image, the projection
associated with the source loop will not be applied to the destination
loop.  This means that if the image's projection is not the same as the
source's projection, the resultant zoom area will not match the source's area. 
On the other hand, if the source loop has an image, and the destination loop
does not, the destination loop will acquire the image projection.  Its zoom
area should match the source's.

When the "Map Window" is invoked from the main NMAP window, the "Load" button
appears at the bottom of the GUI.  Click this button to immediately execute
all changes made to the GUI and re-load all data in the loop.  When the
"Map Window" is invoked from the "Data Selection" window, the "Accept" button
appears at the bottom of the GUI.  Click this button to save all changes to
the "Map Window" which will be applied when data are loaded from the 
"Data Selection" window.
