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<html><head><meta name="generator" content="groff -Thtml, see www.gnu.org"><meta name="Content-Style" content="text/css"><title>snaphu</title></head><body><h1 align=center>snaphu</h1><a href="#NAME">NAME</a><br><a href="#SYNOPSIS">SYNOPSIS</a><br><a href="#DESCRIPTION">DESCRIPTION</a><br><a href="#OPTIONS">OPTIONS</a><br><a href="#FILE FORMATS">FILE FORMATS</a><br><a href="#EXAMPLES">EXAMPLES</a><br><a href="#HINTS AND TIPS">HINTS AND TIPS</a><br><a href="#SIGNALS">SIGNALS</a><br><a href="#EXIT STATUS">EXIT STATUS</a><br><a href="#FILES">FILES</a><br><a href="#BUGS">BUGS</a><br><a href="#REFERENCES">REFERENCES</a><br><hr><!-- Creator : groff version 1.17.2 --><!-- CreationDate: Mon Feb 24 16:21:09 2003 --><a name="NAME"></a><h2>NAME</h2><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%">snaphu - phase unwrapping algorithm for SAR interferometry</td></table><p><a name="SYNOPSIS"></a><h2>SYNOPSIS</h2><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%"><b>snaphu</b> [options] [infile] [linelength][options]</td></table><p><a name="DESCRIPTION"></a><h2>DESCRIPTION</h2><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%"><b>snaphu</b> is a <b>s</b>tatistical-cost<b>n</b>etwork-flow <b>a</b>lgorithm for <b>ph</b>ase<b>u</b>nwrapping. Given an input interferogram and otherobservable data, <b>snaphu</b> attempts to compute congruentphase-unwrapped solutions that are maximally probable in anapproximate <i>a posteriori</i> sense. The algorithm'ssolver routine is based on network optimization. By default,<b>snaphu</b> assumes that its input is a synthetic apertureradar (SAR) interferogram measuring surface topography.Deformation measurements are assumed if the <b>-d</b> optionis given. Smooth, generic data are assumed if the <b>-s</b>option is given.</td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%">This man page documents only <b>snaphu</b>'s syntax andusage. Its theoretical foundations are discussed in thereferences cited below.</td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%">The most common input parameters may be given on the commandline, while many other twiddle parameters are handled viathe <b>-f</b> option and configuration files. At the veryleast, the name of a wrapped-phase input file and its linelength must be specified. Range should increase towards theright in the interferogram, and the flat-earth phase rampshould be removed from the input interferogram before<b>snaphu</b> is run. For deformation interferograms, phasevariations due to topography should be removed aswell.</td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%">Except for the input file name and the line length, allinput parameters take default values if not specified.However, these parameters should be customized wheneverpossible since the accuracy of the solution depends on howwell the statistics of the estimation problem are modeled.To avoid poor-quality solutions, users are stronglyencouraged to provide their best estimates of the relevantproblem parameters. Parameters are set in the order in whichthey are given on the command line, so multipleconfiguration files or options may be given, with latervalues overriding earlier ones.</td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%">Allowable file formats are detailed below. The defaultformat for the input file is COMPLEX_DATA, but any of thedescribed formats may be used. If either of theALT_LINE_DATA or ALT_SAMPLE_DATA formats are used, themagnitude and phase (in radians) of the interferogram shouldbe in the first and second channels of the file,respectively. If the FLOAT_DATA format is used, the inputfile should contain only the phase of the interferogram (inradians); the magnitude may be passed with the <b>-m</b>option.</td></table><p><a name="OPTIONS"></a><h2>OPTIONS</h2><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%"><b>-a</b> <i>ampfile</i></td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="21%"></td><td width="79%">Read brightness data from the file <i>ampfile</i>. The fileshould contain the amplitudes (not powers) of the twoindividual SAR images forming the interferogram if theformats ALT_SAMPLE_DATA (default) or ALT_LINE_DATA are used.It should contain an average of those two images if theFLOAT_DATA format is used. If (1) the amplitudes of bothimages are available, (2) the interferogram magnitude isalso available, and (3) the <b>-c</b> option is not used,then a coherence estimate is automatically formed from theavailable data. The number of looks used for this estimatecan be set in a configuration file. If no amplitude or powerdata are specified, then the magnitude of the inputinterferogram is used as the average amplitude, and nocoherence estimate is formed. Note that the magnitude of theinterferogram is not equal to the average amplitude of theSAR images. The amplitude data should be in the same systemof units used for the input interferogram, and alsocoregistered to it.</td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%"><b>-A</b> <i>pwrfile</i></td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="21%"></td><td width="79%">Similar to the <b>-a</b> option, except the data in thespecified file is assumed to represent the powers of the twoindividual SAR images.</td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%"><b>-b</b> <i>Bperp</i></td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="21%"></td><td width="79%">For topography mode, use <i>Bperp</i> (decimal value, inmeters) as the value of the perpendicular component of theinterferometric baseline. The sign is defined such that<i>Bperp</i> is negative if the unwrapped phase increaseswith the elevation. By default, repeat-pass or ping-pongmode is assumed; for single-antenna-transmit data, the valueof <i>Bperp</i> should be halved, or the transmit modeshould be set accordingly in a configuration file (see the<b>-f</b> option). The baseline value is only used intopography mode.</td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%"><b>-c</b> <i>corrfile</i></td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="21%"></td><td width="79%">Read correlation data from the file <i>corrfile</i>. Thecorrelation data should be the same size as, and registeredto, the input interferogram. Consequently, a raw correlationestimate may need to be upsampled if it incorporates morelooks than the interferogram. If the <b>-c</b> option is notgiven, a coherence estimate is formed from the availabledata if possible. Otherwise, a uniform default coherence isassumed for the entire interferogram. If the ALT_LINE_DATA(default) or ALT_SAMPLE_DATA formats are used, thecorrelation data should be in the second data channel of thefile; the first channel is ignored. The FLOAT_DATA formatmay also be used. The correlation values should be betweenzero and one, inclusive.</td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%"><b>-d</b></td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="21%"></td><td width="79%">Run in deformation mode. The problem statistics andresulting cost functions are based on the assumption thatthe true unwrapped phase represents surface displacementrather than elevation.</td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%"><b>-e</b> <i>estimatefile</i></td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="21%"></td><td width="79%">Flatten using the unwrapped phase estimate in the file<i>estimatefile</i>. The estimate is subtracted from theinput interferogram before unwrapping, and is inserted backinto the solution just before the output is written. Theestimate also affects the cost functions used, sincesubtracting a constant from a random variable shifts theprobability density function of the random variable. If theformats ALT_LINE_DATA (default) or ALT_SAMPLE_DATA are used,the unwrapped estimate (in radians) should be in the seconddata channel of the file; the first channel is ignored. TheFLOAT_DATA format may also be used.</td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%"><b>-f</b> <i>configfile</i></td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="21%"></td><td width="79%">Read configuration parameters from file <i>configfile</i>.The file is parsed line by line for key-value pairs.Template configuration files are included with the<b>snaphu</b> source code: <i>snaphu.conf.full</i> containsall valid key-value pairs; <i>snaphu.conf.brief</i> containsthe most important parameters. Lines not beginning withalphanumeric characters are treated as comment lines.Command line options specified after <b>-f</b> will overrideparameters specified in the <i>configfile</i> and viceversa. The <b>-f</b> option may be given multiple times withdifferent configuration files, with parameters inlater-specified files overriding those in earlierones.</td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="10%"></td><td width="90%"><b>-g</b> <i>maskfile</i></td></table><p><table width="100%" border=0 rules="none" frame="void" cols="2" cellspacing="0" cellpadding="0"><tr valign="top" align="left"><td width="21%"></td><td width="79%">Grow a connected component mask for the unwrapped solutionand write the mask to the file <i>maskfile</i>. A connectedcomponent is a region of pixels in the solution that isbelieved to have been unwrapped in a relative, internallyself-consistent manner according to the statistical costsused. Regions that are smaller than a preselected threshold⌨️ 快捷键说明
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