676 lines
13 KiB
Plaintext
676 lines
13 KiB
Plaintext
.TH MAP 7
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.SH NAME
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map, mapdemo \- draw maps on various projections
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.SH SYNOPSIS
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.B map
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.I projection
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[
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.I option ...
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]
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.PP
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.B mapdemo
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.PP
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.SH DESCRIPTION
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.I Map
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prepares on the standard output a
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map suitable for display by any
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plotting filter described in
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.IR plot (1).
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A menu of projections is produced in response to an unknown
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.IR projection .
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.I Mapdemo
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is a short course in mapping.
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.PP
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The default data for
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.I map
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are world shorelines.
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Option
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.B -f
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accesses more detailed data
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classified by feature.
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.TP
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.BR -f " [ \fIfeature\fR ... ]"
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Features are ranked 1 (default) to 4 from major to minor.
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Higher-numbered ranks include all lower-numbered ones.
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Features are
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.RS
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.TF country[1-3]
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.TP
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.BR shore [ 1 - 4 ]
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seacoasts, lakes, and islands; option
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.B -f
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always shows
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.B shore1
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.TP
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.BR ilake [ 1 - 2 ]
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intermittent lakes
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.TP
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.BR river [ 1 - 4 ]
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rivers
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.TP
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.BR iriver [ 1 - 3 ]
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intermittent rivers
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.TP
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.BR canal [ 1 - 3 ]
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.BR 3 =irrigation
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canals
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.TP
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.BR glacier
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.TP
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.BR iceshelf [ 12 ]
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.TP
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.BR reef
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.TP
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.BR saltpan [ 12 ]
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.TP
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.BR country [ 1 - 3 ]
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.BR 2 =disputed
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boundaries,
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.BR 3 =indefinite
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boundaries
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.TP
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.BR state
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states and provinces (US and Canada only)
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.PD
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.RE
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.PP
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In other options
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coordinates are in degrees, with north latitude
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and west longitude counted as positive.
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.TP 0
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.BI -l " S N E W"
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Set the southern and northern latitude
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and the eastern and western longitude limits.
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Missing arguments are filled out from the list
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\-90, 90, \-180, 180,
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or lesser limits suitable to the
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projection at hand.
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.TP
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.BI -k " S N E W
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Set the scale as if for a map with limits
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.B -l
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.I "S N E W"\f1.
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Do not consider any
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.B -l
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or
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.B -w
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option in setting scale.
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.TP
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.BI -o " lat lon rot"
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Orient the map in a nonstandard position.
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Imagine a transparent gridded sphere around the globe.
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Turn the overlay about the North Pole
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so that the Prime Meridian (longitude 0)
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of the overlay coincides with meridian
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.I lon
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on the globe.
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Then tilt the North Pole of the
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overlay along its Prime Meridian to latitude
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.I lat
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on the globe.
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Finally again turn the
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overlay about its `North Pole' so
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that its Prime Meridian coincides with the previous position
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of meridian
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.IR rot .
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Project the map in
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the standard form appropriate to the overlay, but presenting
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information from the underlying globe.
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Missing arguments are filled out from the list
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90, 0, 0.
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In the absence of
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.BR - o ,
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the orientation is 90, 0,
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.IR m ,
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where
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.I m
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is the middle of the longitude range.
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.TP
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.BI -w " S N E W"
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Window the map by the specified latitudes
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and longitudes in the tilted, rotated coordinate system.
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Missing arguments are filled out from the list \-90, 90, \-180, 180.
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(It is wise to give an encompassing
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.B -l
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option with
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.BR -w .
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Otherwise for small windows computing time
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varies inversely with area!)
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.TP
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.BI -d " n"
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For speed, plot only every
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.IR n th
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point.
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.TP
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.B -r
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Reverse left and right
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(good for star charts and inside-out views).
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.ns
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.TP
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.B -v
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Verso.
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Switch to a normally suppressed sheet of the map, such as the
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back side of the earth in orthographic projection.
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.TP
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.B -s1
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.br
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.ns
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.TP
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.B -s2
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Superpose; outputs for a
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.B -s1
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map (no closing) and a
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.B -s2
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map (no opening) may be concatenated.
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.TP
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.BI -g " dlat dlon res"
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Grid spacings are
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.IR dlat ,
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.IR dlon .
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Zero spacing means no grid.
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Missing
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.I dlat
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is taken to be zero.
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Missing
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.I dlon
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is taken the same as
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.IR dlat .
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Grid lines are drawn to a resolution of
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.I res
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(2° or less by default).
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In the absence of
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.BR - g ,
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grid spacing is 10°.
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.TP
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.BI -p " lat lon extent"
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Position the point
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.I lat, lon
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at the center of the plotting area.
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Scale the map so that the height (and width) of the
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nominal plotting area is
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.I extent
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times the size of one degree of latitude
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at the center.
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By default maps are scaled and positioned
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to fit within the plotting area.
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An
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.I extent
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overrides option
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.BR -k .
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.TP
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.BI -c " x y rot"
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After all other positioning and scaling operations
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have been performed, rotate the image
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.I rot
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degrees counterclockwise about the center
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and move the center to position
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.IR x ,
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.IR y ,
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where the nominal plotting area is
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.RI \-1≤ x ≤1,
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.RI \-1≤ y ≤1.
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Missing arguments are taken to be 0.
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.BR -x
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Allow the map to extend outside the nominal plotting area.
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.TP
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.BR -m " [ \fIfile\fP ... ]"
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Use
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map data from named files.
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If no files are named, omit map data.
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Names that do not exist as pathnames are looked up in
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a standard directory, which contains, in addition to the
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data for
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.BR -f ,
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.RS
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.LP
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.TF counties
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.TP
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.B world
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World Data Bank I (default)
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.TP
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.B states
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US map from Census Bureau
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.TP
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.B counties
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US map from Census Bureau
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.PD
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.RE
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.IP
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The environment variables
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.B MAP
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and
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.B MAPDIR
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change the default
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map and default directory.
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.TP
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.BI -b " \fR[\fPlat0 lon0 lat1 lon1\fR... ]"
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Suppress the drawing of the normal boundary
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(defined by options
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.BR -l
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and
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.BR -w ).
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Coordinates, if present, define the vertices of a
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polygon to which the map is clipped.
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If only two vertices are given, they are taken to be the
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diagonal of a rectangle.
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To draw the polygon, give its vertices as a
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.B -u
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track.
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.TP
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.BI -t " file ..."
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The
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.I files
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contain lists of points,
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given as latitude-longitude pairs in degrees.
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If the first file is named
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.LR - ,
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the standard input is taken instead.
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The points of each list are plotted as connected `tracks'.
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.IP
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Points in a track file may be followed by label strings.
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A label breaks the track.
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A label may be prefixed by
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\fL"\fR,
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.LR : ,
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or
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.L !
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and is terminated by a newline.
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An unprefixed string or a string prefixed with
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.L
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"
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is displayed at the designated point.
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The first word of a
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.L :
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or
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.L !
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string names a special symbol (see option
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.BR -y ).
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An optional numerical second word is a scale factor
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for the size of the symbol, 1 by default.
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A
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.L :
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symbol is aligned with its top to the north; a
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.L !
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symbol is aligned vertically on the page.
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.TP
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.BI -u " file ..."
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Same as
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.BR -t ,
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except the tracks are
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unbroken lines.
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.RB ( -t
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tracks appear as dot-dashed lines if the plotting filter supports them.)
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.TP
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.BI -y " file
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The
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.I file
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contains
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.IR plot (6)-style
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data for
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.L :
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or
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.L !
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labels in
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.B -t
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or
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.B -u
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files.
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Each symbol is defined by a comment
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.BI : name
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then a sequence of
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.L m
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and
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.L v
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commands.
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Coordinates (0,0) fall on the plotting point.
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Default scaling is as if the nominal plotting range were
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.LR "ra -1 -1 1 1" ;
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.L ra
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commands in
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.I file
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change the scaling.
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.SS Projections
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Equatorial projections centered on the Prime Meridian
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(longitude 0).
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Parallels are straight horizontal lines.
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.PP
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.PD 0
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.TP 1.5i
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.B mercator
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equally spaced straight meridians, conformal,
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straight compass courses
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.TP
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.B sinusoidal
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equally spaced parallels,
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equal-area, same as
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.LR "bonne 0" .
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.TP
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.BI cylequalarea " lat0"
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equally spaced straight meridians, equal-area,
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true scale on
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.I lat0
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.TP
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.B cylindrical
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central projection on tangent cylinder
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.TP
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.BI rectangular " lat0"
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equally spaced parallels, equally spaced straight meridians, true scale on
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.I lat0
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.TP
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.BI gall " lat0"
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parallels spaced stereographically on prime meridian, equally spaced straight
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meridians, true scale on
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.I lat0
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.TP
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.B mollweide
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(homalographic) equal-area, hemisphere is a circle
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.br
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.B gilbert()
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sphere conformally mapped on hemisphere and viewed orthographically
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.TP
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.B gilbert
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globe mapped conformally on hemisphere, viewed orthographically
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.PD
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.PP
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Azimuthal projections centered on the North Pole.
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Parallels are concentric circles.
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Meridians are equally spaced radial lines.
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.PP
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.PD 0
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.TP 1.5i
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.B azequidistant
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equally spaced parallels,
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true distances from pole
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.TP
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.B azequalarea
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equal-area
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.TP
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.B gnomonic
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central projection on tangent plane,
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straight great circles
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.TP
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.BI perspective " dist"
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viewed along earth's axis
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.I dist
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earth radii from center of earth
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.TP
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.B orthographic
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viewed from infinity
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.TP
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.B stereographic
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conformal, projected from opposite pole
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.TP
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.B laue
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.IR radius " = tan(2\(mu" colatitude ),
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used in X-ray crystallography
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.TP
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.BI fisheye " n"
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stereographic seen from just inside medium with refractive index
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.I n
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.TP
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.BI newyorker " r"
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.IR radius " = log(" colatitude / r ):
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.I New Yorker
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map from viewing pedestal of radius
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.I r
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degrees
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.PD
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.PP
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Polar conic projections symmetric about the Prime Meridian.
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Parallels are segments of concentric circles.
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Except in the Bonne projection,
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meridians are equally spaced radial
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lines orthogonal to the parallels.
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.PP
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.PD 0
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.TP 1.5i
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.BI conic " lat0"
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central projection on cone tangent at
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.I lat0
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.TP
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.BI simpleconic " lat0 lat1"
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equally spaced parallels, true scale on
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.I lat0
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and
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.I lat1
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.TP
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.BI lambert " lat0 lat1"
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conformal, true scale on
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.I lat0
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and
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.I lat1
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.TP
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.BI albers " lat0 lat1"
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equal-area, true scale on
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.I lat0
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and
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.I lat1
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.TP
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.BI bonne " lat0"
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equally spaced parallels, equal-area,
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parallel
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.I lat0
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developed from tangent cone
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.PD
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.PP
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Projections with bilateral symmetry about
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the Prime Meridian
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and the equator.
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.PP
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.PD 0
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.TP 1.5i
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.B polyconic
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parallels developed from tangent cones,
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equally spaced along Prime Meridian
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.TP
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.B aitoff
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equal-area projection of globe onto 2-to-1
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ellipse, based on
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.I azequalarea
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.TP
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.B lagrange
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conformal, maps whole sphere into a circle
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.TP
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.BI bicentric " lon0"
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points plotted at true azimuth from two
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centers on the equator at longitudes
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.IR ±lon0 ,
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great circles are straight lines
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(a stretched
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.IR gnomonic
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)
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.TP
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.BI elliptic " lon0"
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points plotted at true distance from
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two centers on the equator at longitudes
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.I ±lon0
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.TP
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.B globular
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hemisphere is circle,
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circular arc meridians equally spaced on equator,
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circular arc parallels equally spaced on 0- and 90-degree meridians
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.TP
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.B vandergrinten
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sphere is circle,
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meridians as in
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.IR globular ,
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circular arc parallels resemble
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.I mercator
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.PD
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.PP
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Doubly periodic conformal projections.
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.PP
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.TP 1.5i
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.B guyou
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W and E hemispheres are square
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.PD 0
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.TP
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.B square
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world is square with Poles
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at diagonally opposite corners
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.TP
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.B tetra
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map on tetrahedron with edge
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tangent to Prime Meridian at S Pole,
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unfolded into equilateral triangle
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.TP
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.B hex
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world is hexagon centered
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on N Pole, N and S hemispheres are equilateral
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triangles
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.PD
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.PP
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Miscellaneous projections.
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.PP
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.PD 0
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.TP 1.5i
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.BI harrison " dist angle"
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oblique perspective from above the North Pole,
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.I dist
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earth radii from center of earth, looking
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along the Date Line
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.I angle
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degrees off vertical
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.TP
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.BI trapezoidal " lat0 lat1"
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equally spaced parallels,
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straight meridians equally spaced along parallels,
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true scale at
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.I lat0
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and
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.I lat1
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on Prime Meridian
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.PD
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.br
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.B lune(lat,angle)
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conformal, polar cap above latitude
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.I lat
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maps to convex lune with given
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.I angle
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at 90\(deE and 90\(deW
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.PP
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Retroazimuthal projections.
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At every point the angle between vertical and a straight line to
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`Mecca', latitude
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.I lat0
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on the prime meridian,
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is the true bearing of Mecca.
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.PP
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.PD 0
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.TP 1.5i
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.BI mecca " lat0"
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equally spaced vertical meridians
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.TP
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.BI homing " lat0"
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distances to Mecca are true
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.PD
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.PP
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Maps based on the spheroid.
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Of geodetic quality, these projections do not make sense
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for tilted orientations.
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For descriptions, see corresponding maps above.
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.PP
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.PD 0
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.TP 1.5i
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.B sp_mercator
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.TP
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.BI sp_albers " lat0 lat1"
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.SH EXAMPLES
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.TP
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.L
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map perspective 1.025 -o 40.75 74
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A view looking down on New York from 100 miles
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(0.025 of the 4000-mile earth radius) up.
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The job can be done faster by limiting the map so as not to `plot'
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the invisible part of the world:
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.LR "map perspective 1.025 -o 40.75 74 -l 20 60 30 100".
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A circular border can be forced by adding option
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.LR "-w 77.33" .
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(Latitude 77.33° falls just inside a polar cap of
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opening angle arccos(1/1.025) = 12.6804°.)
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.TP
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.L
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map mercator -o 49.25 -106 180
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An `equatorial' map of the earth
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centered on New York.
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The pole of the map is placed 90\(de away (40.75+49.25=90)
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on the
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other side of the earth.
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A 180° twist around the pole of the map arranges that the
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`Prime Meridian' of the map runs from the pole of the
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map over the North Pole to New York
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instead of down the back side of the earth.
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The same effect can be had from
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.L
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map mercator -o 130.75 74
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.TP
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.L
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map albers 28 45 -l 20 50 60 130 -m states
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A customary curved-latitude map of the United States.
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.TP
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.L
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map harrison 2 30 -l -90 90 120 240 -o 90 0 0
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A fan view covering 60° on either
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side of the Date Line, as seen from one earth radius
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above the North Pole gazing at the
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earth's limb, which is 30° off vertical.
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The
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.B -o
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option overrides the default
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.BR "-o 90 0 180" ,
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which would rotate
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the scene to behind the observer.
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.SH FILES
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.TF /lib/map/[1-4]??
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.TP
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.B /lib/map/[1-4]??
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World Data Bank II, for
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.B -f
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.TP
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.B /lib/map/*
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maps for
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.B -m
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.TP
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.B /lib/map/*.x
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map indexes
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.TP
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.B /bin/aux/mapd
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Map driver program
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.SH SOURCE
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.B /sys/src/cmd/map
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.SH "SEE ALSO"
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.IR map (6),
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.IR plot (1)
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.SH DIAGNOSTICS
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`Map seems to be empty'\(ema coarse survey found
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zero extent within the
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.B -l
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and
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.BR -w
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bounds; for maps of limited extent
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the grid resolution,
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.IR res ,
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or the limits may have to be refined.
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.SH BUGS
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Windows (option
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.BR -w )
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cannot cross the Date Line.
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No borders appear along edges arising from
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visibility limits.
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Segments that cross a border are dropped, not clipped.
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Excessively large scale or
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.B -d
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setting may cause long line segments to be dropped.
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.I Map
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tries to draw grid lines dotted and
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.B -t
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tracks dot-dashed.
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As very few plotting filters properly support
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curved textured lines, these lines are likely to
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appear solid.
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The west-longitude-positive convention
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betrays Yankee chauvinism.
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.I Gilbert
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should be a map from sphere to sphere, independent of
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the mapping from sphere to plane.
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