<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"> <!--Converted with LaTeX2HTML 98.1p1 release (March 2nd, 1998) originally by Nikos Drakos (nikos@cbl.leeds.ac.uk), 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>Mosaicing</TITLE> <META NAME="description" CONTENT="Mosaicing"> <META NAME="keywords" CONTENT="vol2"> <META NAME="resource-type" CONTENT="document"> <META NAME="distribution" CONTENT="global"> <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1"> <LINK REL="STYLESHEET" HREF="vol2.css"> <LINK REL="next" HREF="node664.html"> <LINK REL="previous" HREF="node662.html"> <LINK REL="up" HREF="node655.html"> <LINK REL="next" HREF="node664.html"> </HEAD> <BODY > <!--Navigation Panel--> <A NAME="tex2html9782" HREF="node664.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons.gif/next_motif.gif"></A> <A NAME="tex2html9779" HREF="node655.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons.gif/up_motif.gif"></A> <A NAME="tex2html9773" HREF="node662.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons.gif/previous_motif.gif"></A> <A NAME="tex2html9781" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="icons.gif/contents_motif.gif"></A> <BR> <B> Next:</B> <A NAME="tex2html9783" HREF="node664.html">Further Off-line Analysis</A> <B> Up:</B> <A NAME="tex2html9780" HREF="node655.html">Off-line Reduction</A> <B> Previous:</B> <A NAME="tex2html9774" HREF="node662.html">Combining Images</A> <BR> <BR> <!--End of Navigation Panel--> <H2><A NAME="SECTION003436000000000000000"> </A> <A NAME="irac2:mosaicing"> </A> <BR> Mosaicing </H2> Mosaicing is the name applied to the process by which images of astronomical targets are combined in such a way that the positions of the objects are matched up. This can also lead to a final image larger than the input images if you are, for example, mapping out the IR emission in an extended target. Different reduction packages have several different methods for doing this, but all basically rely on the user specifying the positions of the objects to be matched up from one image to another, and/or specifying the relative shifts between each image that has to be combined. <P> A series of commands in MIDAS are used to perform mosaicing, all included in the <TT>CCDRED</TT> context. <TT>CREATE/MOSAIC</TT> is used first to create a master frame including all the subframes. Alignment of the frames is done using <TT>ALIGN/MOSAIC</TT>, and background levels are matched using <TT>MATCH/MOSAIC</TT> and <TT>FIT/MOSAIC</TT>. Objects to be used in matching the subimages together are selected using the <TT>SHIFT/MOSAIC</TT> command. Overall parameters for the mosaicing routines can be examined using <TT>SHOW/CCD MO</TT> and set using <TT>SET/CCD MO</TT>. More extensive documentation on the mosaicing routines is supplied in the chapter on CCD reductions, Chapter <A HREF="node31.html#ccd:ccd-reductions">3</A>. <P> <HR> <!--Navigation Panel--> <A NAME="tex2html9782" HREF="node664.html"> <IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="icons.gif/next_motif.gif"></A> <A NAME="tex2html9779" HREF="node655.html"> <IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="icons.gif/up_motif.gif"></A> <A NAME="tex2html9773" HREF="node662.html"> <IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="icons.gif/previous_motif.gif"></A> <A NAME="tex2html9781" HREF="node1.html"> <IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="icons.gif/contents_motif.gif"></A> <BR> <B> Next:</B> <A NAME="tex2html9783" HREF="node664.html">Further Off-line Analysis</A> <B> Up:</B> <A NAME="tex2html9780" HREF="node655.html">Off-line Reduction</A> <B> Previous:</B> <A NAME="tex2html9774" HREF="node662.html">Combining Images</A> <!--End of Navigation Panel--> <ADDRESS> <I>Petra Nass</I> <BR><I>1999-06-15</I> </ADDRESS> </BODY> </HTML>
