<!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>B.2.2 Gridline and Pixel node registration</TITLE> <META NAME="description" CONTENT="B.2.2 Gridline and Pixel node registration"> <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="node187.html"> <LINK REL="previous" HREF="node183.html"> <LINK REL="up" HREF="node182.html"> <LINK REL="next" HREF="node185.html"> </HEAD> <BODY bgcolor="#ffffff"> <!--Navigation Panel--> <A NAME="tex2html5341" HREF="node185.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html5335" HREF="node182.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html5329" HREF="node183.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html5337" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <A NAME="tex2html5339" HREF="node258.html"> <IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A> <BR> <B> Next:</B> <A NAME="tex2html5342" HREF="node185.html">B.2.2.1 Gridline registration</A> <B> Up:</B> <A NAME="tex2html5336" HREF="node182.html">B.2 Grid files</A> <B> Previous:</B> <A NAME="tex2html5330" HREF="node183.html">B.2.1 NetCDF files</A> <B> <A NAME="tex2html5338" HREF="node1.html">Contents</A></B> <B> <A NAME="tex2html5340" HREF="node258.html">Index</A></B> <BR> <BR> <!--End of Navigation Panel--> <H2><A NAME="SECTION001922000000000000000"></A> <A NAME="29802"></A> <A NAME="sec:node_registration"></A> <BR> B.2.2 Gridline and Pixel node registration </H2> <P> Scanline format means that the data are stored in rows (<I>y</I> = constant) going from the ``top'' (<IMG WIDTH="58" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" SRC="img214.png" ALT="$y = y_{max}$"> (north)) to the ``bottom'' (<IMG WIDTH="56" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" SRC="img215.png" ALT="$y = y_{min}$"> (south)). Data within each row are ordered from ``left'' (<IMG WIDTH="56" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" SRC="img216.png" ALT="$x = x_{min}$"> (west)) to ``right'' (<IMG WIDTH="58" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" SRC="img217.png" ALT="$x = x_{max}$"> (east)). The <I>node_offset</I> signals how the nodes are laid out. The grid is always defined as the intersections of all <I>x</I> ( <!-- MATH $x = x_{min}, x_{min} + x_{inc}, x_{min} + 2 \cdot x_{inc}, \ldots, x_{max}$ --> <IMG WIDTH="273" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" SRC="img218.png" ALT="\( x = x_{min}, x_{min} + x_{inc}, x_{min} + 2 \cdot x_{inc}, \ldots, x_{max} \)"> ) and <I>y</I> ( <!-- MATH $y = y_{min}, y_{min} + y_{inc}, y_{min} + 2 \cdot y_{inc}, \ldots, y_{max}$ --> <IMG WIDTH="273" HEIGHT="29" ALIGN="MIDDLE" BORDER="0" SRC="img219.png" ALT="\( y = y_{min}, y_{min} + y_{inc}, y_{min} + 2 \cdot y_{inc}, \ldots, y_{max} \)"> ) lines. The two scenarios differ in which area each data point represents. The default node registration in <A NAME="tex2html1734" HREF="http://gmt.soest.hawaii.edu"><B>GMT</B></A> is gridline node registration. Most programs can handle both types, and for some programs like <A NAME="tex2html1735" HREF="../man/grdimage.html"><I><B>grdimage</B></I></A><A NAME="30165"></A> a pixel registered file makes more sense. Utility programs like <A NAME="tex2html1736" HREF="../man/grdsample.html"><I><B>grdsample</B></I></A><A NAME="30170"></A> and <A NAME="tex2html1737" HREF="../man/grdproject.html"><I><B>grdproject</B></I></A><A NAME="30175"></A> will allow you to convert from one format to the other; <A NAME="tex2html1738" HREF="../man/grdedit.html"><I><B>grdedit</B></I></A><A NAME="30180"></A> can make changes to the grid header and convert a pixel- to a gridline-registred grid, or <I>vice versa</I>. <P> <BR><HR> <!--Table of Child-Links--> <A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></A> <UL> <LI><A NAME="tex2html5343" HREF="node185.html">B.2.2.1 Gridline registration</A> <LI><A NAME="tex2html5344" HREF="node186.html">B.2.2.2 Pixel registration</A> </UL> <!--End of Table of Child-Links--> <HR> <!--Navigation Panel--> <A NAME="tex2html5341" HREF="node185.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A> <A NAME="tex2html5335" HREF="node182.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A> <A NAME="tex2html5329" HREF="node183.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A> <A NAME="tex2html5337" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A> <A NAME="tex2html5339" HREF="node258.html"> <IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A> <BR> <B> Next:</B> <A NAME="tex2html5342" HREF="node185.html">B.2.2.1 Gridline registration</A> <B> Up:</B> <A NAME="tex2html5336" HREF="node182.html">B.2 Grid files</A> <B> Previous:</B> <A NAME="tex2html5330" HREF="node183.html">B.2.1 NetCDF files</A> <B> <A NAME="tex2html5338" HREF="node1.html">Contents</A></B> <B> <A NAME="tex2html5340" HREF="node258.html">Index</A></B> <!--End of Navigation Panel--> <ADDRESS> Paul Wessel 2011-02-27 </ADDRESS> </BODY> </HTML>