<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <!--Converted with LaTeX2HTML 2002-2-1 (1.71) original version by: Nikos Drakos, CBLU, University of Leeds * revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan * with significant contributions from: Jens Lippmann, Marek Rouchal, Martin Wilck and others --> <HTML> <HEAD> <TITLE>4.4.2 Coordinate transformations and map projections: The -J option</TITLE> <META NAME="description" CONTENT="4.4.2 Coordinate transformations and map projections: The -J option"> <META NAME="keywords" CONTENT="GMT_Docs"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <META NAME="Generator" CONTENT="LaTeX2HTML v2002-2-1"> <META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css"> <LINK REL="STYLESHEET" HREF="GMT_Docs.css"> <LINK REL="next" HREF="node42.html"> <LINK REL="previous" HREF="node40.html"> <LINK REL="up" HREF="node39.html"> <LINK REL="next" HREF="node42.html"> </HEAD> <BODY bgcolor="#ffffff"> <!--Navigation Panel--> <A NAME="tex2html3207" HREF="node42.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html3201" HREF="node39.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html3195" HREF="node40.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html3203" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <A NAME="tex2html3205" HREF="node258.html"> <IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A> <BR> <B> Next:</B> <A NAME="tex2html3208" HREF="node42.html">4.4.3 Map frame and</A> <B> Up:</B> <A NAME="tex2html3202" HREF="node39.html">4.4 Standardized command line</A> <B> Previous:</B> <A NAME="tex2html3196" HREF="node40.html">4.4.1 Data domain or</A> <B> <A NAME="tex2html3204" HREF="node1.html">Contents</A></B> <B> <A NAME="tex2html3206" HREF="node258.html">Index</A></B> <BR> <BR> <!--End of Navigation Panel--> <H2><A NAME="SECTION001242000000000000000"> 4.4.2 Coordinate transformations and map projections: The <B>-J</B> option</A> </H2> <A NAME="19154"></A> <A NAME="18010"></A> <P> This option selects the coordinate transformation or map projection. The general format is <UL> <LI><B>-J</B><IMG WIDTH="14" HEIGHT="31" ALIGN="MIDDLE" BORDER="0" SRC="img45.png" ALT="$\delta$">[<I>parameters</I>/]<I>scale</I>. Here, <IMG WIDTH="14" HEIGHT="31" ALIGN="MIDDLE" BORDER="0" SRC="img45.png" ALT="$\delta$"> is a <I>lower-case</I> letter of the alphabet that selects a particular map projection, the <I>parameters</I> is zero or more slash-delimited projection parameter, and <I>scale</I> is map scale given in distance units per degree or as 1:xxxxx. </LI> <LI><B>-J</B><IMG WIDTH="14" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" SRC="img46.png" ALT="$\Delta$">[<I>parameters</I>/]<I>width</I>. Here, <IMG WIDTH="14" HEIGHT="14" ALIGN="BOTTOM" BORDER="0" SRC="img46.png" ALT="$\Delta$"> is an <I>upper-case</I> letter of the alphabet that selects a particular map projection, the <I>parameters</I> is zero or more slash-delimited projection parameter, and <I>width</I> is map width (map height is automatically computed from the implied map scale and region). </LI> </UL> Since <A NAME="tex2html1178" HREF="http://gmt.soest.hawaii.edu"><B>GMT</B></A> version 4.3.0, there is an alternative way to specify the projections: use the same abbreviation as in the mapping package <I>Proj4</I><A NAME="19445"></A>. The options thus either look like: <UL> <LI><B>-Jabbrev/</B>[<I>parameters</I>/]<I>scale</I>. Here, <B>abbrev</B> is a <I>lower-case</I> abbreviation that selects a particular map projection, the <I>parameters</I> is zero or more slash-delimited projection parameter, and <I>scale</I> is map scale given in distance units per degree or as 1:xxxxx. </LI> <LI><B>-JAbbrev/</B>[<I>parameters</I>/]<I>width</I>. Here, <B>Abbrev</B> is an <I>capitalized</I> abbreviation that selects a particular map projection, the <I>parameters</I> is zero or more slash-delimited projection parameter, and <I>width</I> is map width (map height is automatically computed from the implied map scale and region). </LI> </UL> <P> <DIV ALIGN="CENTER"><A NAME="fig:GMT_-J"></A><A NAME="19451"></A> <TABLE> <CAPTION ALIGN="BOTTOM"><STRONG>Figure:</STRONG> The 30+ map projections and coordinate transformations available in <A NAME="tex2html1175" HREF="http://gmt.soest.hawaii.edu"><B>GMT</B></A>.</CAPTION> <TR><TD> <DIV ALIGN="CENTER"><IMG WIDTH="526" HEIGHT="326" ALIGN="BOTTOM" BORDER="0" SRC="img47.png" ALT="\includegraphics{scripts/GMT_-J}"></DIV></TD></TR> </TABLE> </DIV> <P> The projections available in <A NAME="tex2html1179" HREF="http://gmt.soest.hawaii.edu"><B>GMT</B></A> are presented in Figure <A HREF="#fig:GMT_-J">4.5</A>. For details on all <A NAME="tex2html1180" HREF="http://gmt.soest.hawaii.edu"><B>GMT</B></A> projections and the required parameters, see the <A NAME="tex2html1181" HREF="../man/psbasemap.html"><I><B>psbasemap</B></I></A><A NAME="19465"></A> man page. We will also show examples of every projection in the next Chapters, and a quick summary of projection syntax was given in Chapter <A HREF="node30.html#ch:3">3</A>. <P> <HR> <!--Navigation Panel--> <A NAME="tex2html3207" HREF="node42.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html3201" HREF="node39.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html3195" HREF="node40.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html3203" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <A NAME="tex2html3205" HREF="node258.html"> <IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A> <BR> <B> Next:</B> <A NAME="tex2html3208" HREF="node42.html">4.4.3 Map frame and</A> <B> Up:</B> <A NAME="tex2html3202" HREF="node39.html">4.4 Standardized command line</A> <B> Previous:</B> <A NAME="tex2html3196" HREF="node40.html">4.4.1 Data domain or</A> <B> <A NAME="tex2html3204" HREF="node1.html">Contents</A></B> <B> <A NAME="tex2html3206" HREF="node258.html">Index</A></B> <!--End of Navigation Panel--> <ADDRESS> Paul Wessel 2011-02-27 </ADDRESS> </BODY> </HTML>