1Ppmglobe User Manual(0)                                Ppmglobe User Manual(0)
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NAME

6       ppmglobe - generate strips to glue onto a sphere
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SYNOPSIS

10       ppmglobe [-background=colorname] [-closeok] stripcount [filename]
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12       Minimum  unique abbreviation of option is acceptable.  You may use dou‐
13       ble hyphens instead of single hyphen to denote options.   You  may  use
14       white space in place of the equals sign to separate an option name from
15       its value.
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DESCRIPTION

20       This program is part of Netpbm(1).
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22       ppmglobe does the inverse of a  cylindrical  projection  of  a  sphere.
23       Starting  with  a  cylindrical projection, it produces an image you can
24       cut up and glue onto a sphere to obtain the spherical image of which it
25       is the cylindrical projection.
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27       What  is  a cylindrical projection?  Imagine a map of the Earth on flat
28       paper.  There are lots of different ways cartographers show  the  three
29       dimensional information in such a two dimensional map.  The cylindrical
30       projection is one.  You could make a cylindrical projection by  tracing
31       as folows: wrap a rectangular sheet of paper around the globe, touching
32       the globe at the Equator.  For each point of color on the globe, run  a
33       horizontal  line  from the axis of the globe through that point and out
34       to the paper.  Mark the same color on the paper there.  Lay  the  paper
35       out flat and you have a cylindrical projection.
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37       Here's  where  ppmglobe comes in:  Pass the image on that paper through
38       ppmglobe and what comes out the other side looks something like this:
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40       Example of map of the earth run through ppmglobe
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42       You could cut out the strips and glue it onto a sphere and you'd have a
43       copy of the original globe.
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45       Note that cylindrical projections are not what you normally see as maps
46       of the Earth.  You're more likely to see a Mercator projection.  In the
47       Mercator  projection,  the  Earth gets stretched North-South as well as
48       East-West as you move away from the Equator.  It was invented  for  use
49       in navigation, because you can draw straight compass courses on it, but
50       is used today because it is pretty.
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52       You    can    find    maps    of    planets    at     maps.jpl.nasa.gov
53http://maps.jpl.nasa.gov⟩ .
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PARAMETERS

57       stripcount  is the number of strips ppmglobe is to generate in the out‐
58       put.  More strips makes it easier to fit onto a sphere  (less  stretch‐
59       ing,  tearing,  and  crumpling of paper), but makes you do more cutting
60       out of the strips.
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62       The strips are all the same width.  If the number of columns of  pixels
63       in  the  image  doesn't evenly divide by the number of strips, ppmglobe
64       truncates the image on the right to create nothing  but  whole  strips.
65       In  the  pathological  case that there are fewer columns of pixels than
66       the number of strips you asked for, ppmglobe fails.
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68       Before Netpbm 10.32 (February 2006), instead of truncating the image on
69       the right, ppmglobe produces a fractional strip on the right.
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71       filename  is  the  name  of the input file.  If you don't specify this,
72       ppmglobe reads the image from Standard Input.
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OPTIONS

77       -background=colorname
78              This specifies the color that goes between the strips.
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80              Specify the color (color) as described for the argument  of  the
81              pnm_parsecolor()                 library                 routine
82              ⟨libnetpbm_image.html#colorname⟩ .
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84              The default is black.
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86              This option was new in Netpbm  10.31  (December  2005).   Before
87              that, the background is always black.
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90       -closeok
91              This  means  it  is OK if the background isn't exactly the color
92              you specify.  Sometimes, it is impossible to represent  a  named
93              color  exactly  because  of  the  precision (i.e. maxval) of the
94              image's color space.  If you specify -closeok and ppmglobe can't
95              represent  the  color  you name exactly, it will use instead the
96              closest color to it that is  possible.   If  you  don't  specify
97              closeok, ppmglobe fails in that situation.
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99              This option was new in Netpbm 10.31 (December 2005).
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SEE ALSO

105       ppm(1) pnmmercator(1)
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HISTORY

109       ppmglobe was new in Netpbm 10.16 (June 2003).
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111       It is derived from Max Gensthaler's ppmglobemap.
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AUTHORS

115       Max  Gensthaler  wrote a program he called ppmglobemap in June 2003 and
116       suggested it for inclusion in Netpbm.   Bryan  Henderson  modified  the
117       code slightly and included it in Netpbm as ppmglobe.
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DOCUMENT SOURCE

120       This  manual  page was generated by the Netpbm tool 'makeman' from HTML
121       source.  The master documentation is at
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123              http://netpbm.sourceforge.net/doc/ppmglobe.html
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125netpbm documentation           23 February 2006        Ppmglobe User Manual(0)
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