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| author | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2006-12-25 03:06:05 +0000 |
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| committer | giraffedata <giraffedata@9d0c8265-081b-0410-96cb-a4ca84ce46f8> | 2006-12-25 03:06:05 +0000 |
| commit | 1017cbebe5d5edd859e0fddad0a8600f509f4821 (patch) | |
| tree | 78bdf336648566f7a7d55f42837357dea3dd674c /ppmglobe.html | |
| parent | 16f2ac126651015a376eba864a3a35f738b0b25a (diff) | |
| download | netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.tar.gz netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.tar.xz netpbm-mirror-1017cbebe5d5edd859e0fddad0a8600f509f4821.zip | |
Place user guide into Subversion repository
git-svn-id: http://svn.code.sf.net/p/netpbm/code/userguide@181 9d0c8265-081b-0410-96cb-a4ca84ce46f8
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diff --git a/ppmglobe.html b/ppmglobe.html new file mode 100644 index 00000000..ff1c3e39 --- /dev/null +++ b/ppmglobe.html @@ -0,0 +1,148 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 3.2//EN"> +<HTML> +<HEAD><TITLE>Ppmglobe User Manual</TITLE></HEAD> +<BODY> +<H1>ppmglobe</H1> +Updated: 23 February 2006 +<BR> +<A HREF="#index">Table Of Contents</A> + +<H2 id="name">NAME</H2> + +ppmglobe - generate strips to glue onto a sphere + +<H2 id="synopsis">SYNOPSIS</H2> + +<B>ppmglobe</B> +[<b>-background=</b><i>colorname</i>] +[<b>-closeok</b>] +<i>stripcount</i> +[<i>filename</i>] + +<P>Minimum unique abbreviation of option is acceptable. You may use double +hyphens instead of single hyphen to denote options. You may use white +space in place of the equals sign to separate an option name from its value. + + +<H2 id="description">DESCRIPTION</H2> + +<p>This program is part of <a href="index.html">Netpbm</a>. + +<p><b>ppmglobe</b> does the inverse of a cylindrical projection of a +sphere. Starting with a cylindrical projection, it produces an image +you can cut up and glue onto a sphere to obtain the spherical image of +which it is the cylindrical projection. + +<p>What is a cylindrical projection? Imagine a map of the Earth on +flat paper. There are lots of different ways cartographers show the +three dimensional information in such a two dimensional map. The +cylindrical projection is one. You could make a cylindrical projection +by putting a light inside a globe and wrapping a rectangular sheet of +paper around the globe, touching the globe at the Equator. Then trace +the image that the light projects onto the paper. Lay the paper out flat +and you have a cylindrical projection. + +<p>Here's where <b>ppmglobe</b> comes in: Pass the image on that paper +through <b>ppmglobe</b> and what comes out the other side looks something +like this: + +<p> +<img src="globe.jpg" alt="Example of map of the earth run through ppmglobe"> + +<p>You could cut out the strips and glue it onto a sphere and you'd +have a copy of the original globe. + +<p>Note that cylindrical projections are not what you normally see as +maps of the Earth. You're more likely to see a Mercator projection. +In the Mercator projection, the Earth gets stretched North-South as +well as East-West as you move away from the Equator. It was invented +for use in navigation, because you can draw straight compass courses +on it, but is used today because it is pretty. + +<p>You can find maps of planets at <a +href="http://maps.jpl.nasa.gov">maps.jpl.nasa.gov</a>. + +<H2 id="parameters">PARAMETERS</H2> + +<p><i>stripcount</i> is the number of strips <b>ppmglobe</b> is to +generate in the output. More strips makes it easier to fit onto a +sphere (less stretching, tearing, and crumpling of paper), but makes +you do more cutting out of the strips. + +<p>The strips are all the same width. If the number of columns of +pixels in the image doesn't evenly divide by the number of strips, +<b>ppmglobe</b> truncates the image on the right to create nothing but +whole strips. In the pathological case that there are fewer columns +of pixels than the number of strips you asked for, <b>ppmglobe</b> +fails. + +<p>Before Netpbm 10.32 (February 2006), instead of truncating the image +on the right, <b>ppmglobe</b> produces a fractional strip on the right. + +<p><i>filename</i> is the name of the input file. If you don't +specify this, <b>ppmglobe</b> reads the image from Standard Input. + + +<H2 id="options">OPTIONS</H2> + +<DL COMPACT> + +<DT><B>-background=</B><I>colorname</I> +<DD> +This specifies the color that goes between the strips. + +<P>Specify the color (<i>color</i>) as described for the <a +href="libppm.html#colorname">argument of the <b>ppm_parsecolor()</b> +library routine</a>. + +<p>The default is black. + +<p>This option was new in Netpbm 10.31 (December 2005). Before that, +the background is always black. + +<DT><B>-closeok</B> +<DD> +This means it is OK if the background isn't exactly the color you specify. +Sometimes, it is impossible to represent a named color exactly due to the +precision (i.e. maxval) of the image's color space. If you specify +<b>-closeok</b> and <b>ppmglobe</b> can't represent the color you name +exactly, it will use instead the closest color to it that is possible. +If you don't specify <b>closeok</b>, <b>ppmglobe</b> fails in that +situation. + +<p>This option was new in Netpbm 10.31 (December 2005). + +</DL> + +<H2 id="seealso">SEE ALSO</H2> + +<B><A HREF="ppm.html">ppm</A></B> + +<H2 id="history">HISTORY</H2> + +<P><b>ppmglobe</b> was new in Netpbm 10.16 (June 2003). + +<p>It is derived from <a href="http://www.gensthaler.de/projekte/ppmglobemap"> +Max Gensthaler's <b>ppmglobemap</b></a>. + +<H2 id="authors">AUTHORS</H2> + +<p><a href="mailto:Max@Gensthaler.de">Max Gensthaler</a> +wrote a program he called +<b>ppmglobemap</b> in June 2003 and suggested it for inclusion in +Netpbm. Bryan Henderson modified the code slightly and included it in +Netpbm as <b>ppmglobe</b>. + +<HR> +<A NAME="index"> </A><H2>Table Of Contents</H2> +<UL> +<LI><A HREF="#name">NAME</A> +<LI><A HREF="#synopsis">SYNOPSIS</A> +<LI><A HREF="#description">DESCRIPTION</A> +<LI><A HREF="#parameters">PARAMETERS</A> +<LI><A HREF="#options">OPTIONS</A> +<LI><A HREF="#seealso">SEE ALSO</A> +<LI><A HREF="#authors">AUTHORS</A> +</UL> +</BODY> +</HTML> |