glenda.party
term% ls -F
term% cat index.txt
MAP(7)                 Miscellaneous Information Manual                 MAP(7)



NAME
       map, mapdemo - draw maps on various projections

SYNOPSIS
       map projection [ option ...  ]

       mapdemo

DESCRIPTION
       Map  prepares  on the standard output a map suitable for display by any
       plotting filter described in plot(1).  A menu of  projections  is  pro‐
       duced  in response to an unknown projection.  Mapdemo is a short course
       in mapping.

       The default data for map are world shorelines.  Option -f accesses more
       detailed data classified by feature.

       -f [ feature ... ]
              Features  are  ranked  1  (default)  to  4  from major to minor.
              Higher-numbered ranks include all lower-numbered ones.  Features
              are

              shore[1-4]
                     seacoasts,  lakes,  and  islands;  option -f always shows
                     shore1

              ilake[1-2]
                     intermittent lakes

              river[1-4]
                     rivers

              iriver[1-3]
                     intermittent rivers

              canal[1-3]
                     3=irrigation canals

              glacier

              iceshelf[12]

              reef

              saltpan[12]

              country[1-3]
                     2=disputed boundaries, 3=indefinite boundaries

              state  states and provinces (US and Canada only)

       In other options coordinates are in degrees, with  north  latitude  and
       west longitude counted as positive.

       -l S N E W
       Set the southern and northern latitude and the eastern and western lon‐
       gitude limits.  Missing arguments are filled out from the list -90, 90,
       -180, 180, or lesser limits suitable to the projection at hand.

       -k S N E W
       Set the scale as if for a map with limits -l S N E W .  Do not consider
       any -l or -w option in setting scale.

       -o lat lon rot
       Orient the map in a nonstandard position.  Imagine a transparent  grid‐
       ded  sphere around the globe.  Turn the overlay about the North Pole so
       that the Prime Meridian (longitude 0) of  the  overlay  coincides  with
       meridian  lon  on  the  globe.  Then tilt the North Pole of the overlay
       along its Prime Meridian to latitude lat on the globe.   Finally  again
       turn  the overlay about its `North Pole' so that its Prime Meridian co‐
       incides with the previous position of meridian rot.  Project the map in
       the  standard  form appropriate to the overlay, but presenting informa‐
       tion from the underlying globe.  Missing arguments are filled out  from
       the  list 90, 0, 0.  In the absence of -o, the orientation is 90, 0, m,
       where m is the middle of the longitude range.

       -w S N E W
       Window the map by the specified latitudes and longitudes in the tilted,
       rotated  coordinate  system.  Missing arguments are filled out from the
       list -90, 90, -180, 180.  (It is wise to give an encompassing -l option
       with  -w.   Otherwise for small windows computing time varies inversely
       with area!)

       -d n
       For speed, plot only every nth point.

       -r
       Reverse left and right (good for star charts and inside-out views).

       -v
       Verso.  Switch to a normally suppressed sheet of the map, such  as  the
       back side of the earth in orthographic projection.

       -s1
       -s2
       Superpose;  outputs  for a -s1 map (no closing) and a -s2 map (no open‐
       ing) may be concatenated.

       -g dlat dlon res
       Grid spacings are dlat, dlon.  Zero spacing  means  no  grid.   Missing
       dlat  is  taken  to  be  zero.  Missing dlon is taken the same as dlat.
       Grid lines are drawn to a resolution of res (2° or less  by  default).
       In the absence of -g, grid spacing is 10°.

       -p lat lon extent
       Position  the point lat, lon at the center of the plotting area.  Scale
       the map so that the height (and width) of the nominal plotting area  is
       extent  times the size of one degree of latitude at the center.  By de‐
       fault maps are scaled and positioned to fit within the  plotting  area.
       An extent overrides option -k.

       -c x y rot
       After all other positioning and scaling operations have been performed,
       rotate the image rot degrees counterclockwise about the center and move
       the  center  to  position  x,  y,  where  the  nominal plotting area is
       -1â¤xâ¤1, -1â¤yâ¤1.  Missing arguments are taken to be 0.  -x Allow the
       map to extend outside the nominal plotting area.

       -m [ file ... ]
       Use  map  data from named files.  If no files are named, omit map data.
       Names that do not exist as pathnames are looked up in a standard direc‐
       tory, which contains, in addition to the data for -f,

       world  World Data Bank I (default)

       states US map from Census Bureau

       counties
              US map from Census Bureau

       The environment variables MAP and MAPDIR change the default map and de‐
       fault directory.

       -b [lat0 lon0 lat1 lon1... ]
       Suppress the drawing of the normal boundary (defined by options -l  and
       -w).   Coordinates,  if  present,  define  the vertices of a polygon to
       which the map is clipped.  If only two vertices  are  given,  they  are
       taken to be the diagonal of a rectangle.  To draw the polygon, give its
       vertices as a -u track.

       -t file ...
       The files contain lists of points, given as latitude-longitude pairs in
       degrees.   If  the  first file is named the standard input is taken in‐
       stead.  The points of each list are plotted as connected `tracks'.

       Points in a track file may be  followed  by  label  strings.   A  label
       breaks  the  track.  A label may be prefixed by ", or and is terminated
       by a newline.  An unprefixed string or a string prefixed with " is dis‐
       played  at the designated point.  The first word of a or string names a
       special symbol (see option -y).  An optional numerical second word is a
       scale  factor  for  the  size of the symbol, 1 by default.  A symbol is
       aligned with its top to the north; a symbol is  aligned  vertically  on
       the page.

       -u file ...
       Same as -t, except the tracks are unbroken lines.  (-t tracks appear as
       dot-dashed lines if the plotting filter supports them.)

       -y file
       The file contains plot(6)-style data for or labels in -t or  -u  files.
       Each  symbol  is defined by a comment :name then a sequence of and com‐
       mands.  Coordinates (0,0) fall on the plotting point.  Default  scaling
       is  as  if  the nominal plotting range were commands in file change the
       scaling.

   Projections
       Equatorial projections centered on the Prime  Meridian  (longitude  0).
       Parallels are straight horizontal lines.

       mercator       equally  spaced  straight meridians, conformal, straight
                      compass courses
       sinusoidal     equally spaced parallels, equal-area, same as
       cylequalarea lat0
                      equally  spaced  straight  meridians,  equal-area,  true
                      scale on lat0
       cylindrical    central projection on tangent cylinder
       rectangular lat0
                      equally spaced parallels, equally spaced straight merid‐
                      ians, true scale on lat0
       gall lat0      parallels spaced stereographically  on  prime  meridian,
                      equally spaced straight meridians, true scale on lat0
       mollweide      (homalographic) equal-area, hemisphere is a circle
                      gilbert()  sphere  conformally  mapped on hemisphere and
                      viewed orthographically
       gilbert        globe mapped conformally on  hemisphere,  viewed  ortho‐
                      graphically

       Azimuthal  projections  centered on the North Pole.  Parallels are con‐
       centric circles.  Meridians are equally spaced radial lines.

       azequidistant  equally spaced parallels, true distances from pole
       azequalarea    equal-area
       gnomonic       central projection on tangent plane, straight great cir‐
                      cles
       perspective dist
                      viewed  along  earth's axis dist earth radii from center
                      of earth
       orthographic   viewed from infinity
       stereographic  conformal, projected from opposite pole
       laue           radius = tan(2×colatitude), used in X-ray  crystallogra‐
                      phy
       fisheye n      stereographic  seen from just inside medium with refrac‐
                      tive index n
       newyorker r    radius = log(colatitude/r): New Yorker map from  viewing
                      pedestal of radius r degrees

       Polar  conic projections symmetric about the Prime Meridian.  Parallels
       are segments of concentric circles.  Except in  the  Bonne  projection,
       meridians are equally spaced radial lines orthogonal to the parallels.

       conic lat0     central projection on cone tangent at lat0
       simpleconic lat0 lat1
                      equally spaced parallels, true scale on lat0 and lat1
       lambert lat0 lat1
                      conformal, true scale on lat0 and lat1
       albers lat0 lat1
                      equal-area, true scale on lat0 and lat1
       bonne lat0     equally  spaced parallels, equal-area, parallel lat0 de‐
                      veloped from tangent cone

       Projections with bilateral symmetry about the Prime  Meridian  and  the
       equator.

       polyconic      parallels  developed  from tangent cones, equally spaced
                      along Prime Meridian
       aitoff         equal-area projection  of  globe  onto  2-to-1  ellipse,
                      based on azequalarea
       lagrange       conformal, maps whole sphere into a circle
       bicentric lon0 points  plotted  at true azimuth from two centers on the
                      equator at longitudes ±lon0, great circles are straight
                      lines (a stretched gnomonic )
       elliptic lon0  points  plotted at true distance from two centers on the
                      equator at longitudes ±lon0
       globular       hemisphere is circle,  circular  arc  meridians  equally
                      spaced on equator, circular arc parallels equally spaced
                      on 0- and 90-degree meridians
       vandergrinten  sphere is circle, meridians as in globular, circular arc
                      parallels resemble mercator

       Doubly periodic conformal projections.

       guyou          W and E hemispheres are square
       square         world  is  square with Poles at diagonally opposite cor‐
                      ners
       tetra          map on tetrahedron with edge tangent to  Prime  Meridian
                      at S Pole, unfolded into equilateral triangle
       hex            world is hexagon centered on N Pole, N and S hemispheres
                      are equilateral triangles

       Miscellaneous projections.

       harrison dist angle
                      oblique perspective from  above  the  North  Pole,  dist
                      earth radii from center of earth, looking along the Date
                      Line angle degrees off vertical
       trapezoidal lat0 lat1
                      equally spaced  parallels,  straight  meridians  equally
                      spaced  along  parallels, true scale at lat0 and lat1 on
                      Prime Meridian
                      lune(lat,angle) conformal, polar cap above latitude  lat
                      maps to convex lune with given angle at 90°E and 90°W

       Retroazimuthal  projections.  At every point the angle between vertical
       and a straight line to `Mecca', latitude lat0 on the prime meridian, is
       the true bearing of Mecca.

       mecca lat0     equally spaced vertical meridians
       homing lat0    distances to Mecca are true

       Maps  based on the spheroid.  Of geodetic quality, these projections do
       not make sense for tilted orientations.  For descriptions,  see  corre‐
       sponding maps above.

       sp_mercator
       sp_albers lat0 lat1
EXAMPLES
       map perspective 1.025 -o 40.75 74
              A  view  looking  down  on New York from 100 miles (0.025 of the
              4000-mile earth radius) up.  The job can be done faster by  lim‐
              iting  the  map  so  as  not to `plot' the invisible part of the
              world: A circular border can be forced by adding  option  (Lati‐
              tude 77.33° falls just inside a polar cap of opening angle arc‐
              cos(1/1.025) = 12.6804°.)
       map mercator -o 49.25 -106 180
              An `equatorial' map of the earth centered on New York.  The pole
              of the map is placed 90° away (40.75+49.25=90) on the other side
              of the earth.  A 180° twist around the pole of the map arranges
              that  the  `Prime Meridian' of the map runs from the pole of the
              map over the North Pole to New York instead  of  down  the  back
              side of the earth.  The same effect can be had from map mercator
              -o 130.75 74
       map albers 28 45 -l 20 50 60 130 -m states
              A customary curved-latitude map of the United States.
       map harrison 2 30 -l -90 90 120 240 -o 90 0 0
              A fan view covering 60° on either side of  the  Date  Line,  as
              seen  from  one  earth radius above the North Pole gazing at the
              earth's limb, which is 30° off vertical.  The -o  option  over‐
              rides  the  default -o 90 0 180, which would rotate the scene to
              behind the observer.
FILES
       /lib/map/[1-4]??
              World Data Bank II, for -f
       /lib/map/*
              maps for -m
       /lib/map/*.x
              map indexes
       /bin/aux/mapd
              Map driver program
SOURCE
       /sys/src/cmd/map
SEE ALSO
       map(6), plot(1)
DIAGNOSTICS
       `Map seems to be empty'—a coarse survey found zero extent within the -l
       and  -w bounds; for maps of limited extent the grid resolution, res, or
       the limits may have to be refined.
BUGS
       Windows (option -w) cannot cross the  Date  Line.   No  borders  appear
       along edges arising from visibility limits.  Segments that cross a bor‐
       der are dropped, not clipped.  Excessively large scale  or  -d  setting
       may  cause  long  line  segments to be dropped.  Map tries to draw grid
       lines dotted and -t tracks dot-dashed.  As very  few  plotting  filters
       properly  support  curved textured lines, these lines are likely to ap‐
       pear solid.   The  west-longitude-positive  convention  betrays  Yankee
       chauvinism.  Gilbert should be a map from sphere to sphere, independent
       of the mapping from sphere to plane.



                                                                        MAP(7)