snaphu.conf.brief

phase unwrapping algorithm for SAR interferometry

# snaphu configuration file
#
# Lines with fewer than two fields and lines whose first non-whitespace 
# characters are not alphnumeric are ignored.  For the remaining lines, 
# anything after the first two fields (delimited by whitespace) is 
# also ignored.  Inputs are converted in the order they appear in the file; 
# if multiple assignments are made to the same parameter, the last one 
# given is the one used.  Parameters in this file will be superseded by 
# parameters given on the command line after the -f flag specifying this
# file.  Multiple configuration files may be given on the command line.



#############################################
# File input and output and runtime options #
#############################################

# See section below for file format configuration options.

# Input file name
# INFILE	snaphu.in

# Input file line length 
# LINELENGTH	1000

# Output file name
# OUTFILE	snaphu.out

# Amplitude file name(s)
# AMPFILE	snaphu.amp.in	# Single file containing amplitude images

# Correlation file name
# CORRFILE	snaphu.corr.in

# Statistical-cost mode (TOPO, DEFO, SMOOTH, or NOSTATCOSTS)
# STATCOSTMODE	TOPO

# Initialize-only mode (TRUE or FALSE)
# INITONLY	FALSE

# Algorithm used for initialization of wrapped phase values.  Possible
# values are MST and MCF.  
# INITMETHOD	MST

# Verbose-output mode (TRUE or FALSE)
# VERBOSE	FALSE


################
# File formats #
################

# Valid data formats:
#
# COMPLEX_DATA:      complex values: real, imag, real, imag
# ALT_LINE_DATA:     real values from different arrays, alternating by line
# ALT_SAMPLE_DATA:   real values from different arrays, alternating by sample
# FLOAT_DATA:        single array of floating-point data
# 

# The ALT_SAMPLE_DATA format is sometimes known as .amp or sample-
# interleaved format; the ALT_LINE_DATA format is sometimes known as
# .hgt or line-interleaved format.  For the ALT_LINE_DATA format, the
# first array is always assumed to be the interferogram magnitude.  All
# formats assume single-precision (32-bit) floating-point data (real*4
# and complex*8 in Fortran) in the native byte order (big vs. little
# endian) of the system.


# Input file format
# Allowable formats:
#   COMPLEX_DATA        (default)
#   ALT_LINE_DATA       (magnitude in channel 1, phase in radians in channel 2)
#   ALT_SAMPLE_DATA     (magnitude in channel 1, phase in radians in channel 2)
#   FLOAT_DATA          (phase in radians)
#
#INFILEFORMAT		COMPLEX_DATA

# Output file format
# Allowable formats:
#   ALT_LINE_DATA       (interferogram magnitude in channel 1, 
#                        unwrapped phase in radians in channel 2; default)
#   ALT_SAMPLE_DATA     (interferogram magnitude in channel 1, 
#                        unwrapped phase in radians in channel 2)
#   FLOAT_DATA          (unwrapped phase in radians)
#
#OUTFILEFORMAT		ALT_LINE_DATA

# Amplitude or power file format
# Units should be consistent with interferogram.  Allowable formats:
#   ALT_LINE_DATA       (first image amplitude in channel 1, 
#                        second image amplitude in channel 2)
#   ALT_SAMPLE_DATA     (first image amplitude in channel 1, 
#                        second image amplitude in channel 2; default)
#   FLOAT_DATA          (square root of average power of two images)
#
#AMPFILEFORMAT		ALT_SAMPLE_DATA

# Correlation file format
# Allowable formats:
#   ALT_LINE_DATA       (channel 1 ignored; correlation values 
#                        between 0 and 1 in channel 2; default)
#   ALT_SAMPLE_DATA     (channel 1 ignored; correlation values 
#                        between 0 and 1 in channel 2)
#   FLOAT_DATA          (correlation values between 0 and 1)
#
#CORRFILEFORMAT		ALT_LINE_DATA


###############################
# SAR and geometry parameters #
###############################

# Orbital radius (double, meters) or altitude (double, meters).  The
# radius should be the local radius if the orbit is not circular.  The
# altitude is just defined as the orbit radius minus the earth radius.
# Only one of these two parameters should be given.  
ORBITRADIUS		7153000.0
#ALTITUDE		775000.0

# Local earth radius (double, meters).  A spherical-earth model is
# used.
EARTHRADIUS		6378000.0

# The baseline parameters are not used in deformation mode, but they
# are very important in topography mode.  The parameter BASELINE
# (double, meters) is the physical distance (always positive) between
# the antenna phase centers.  The along-track componenet of the
# baseline is assumed to be zero.  The parameter BASELINEANGLE_DEG
# (double, degrees) is the angle between the antenna phase centers
# with respect to the local horizontal.  Suppose the interferogram is
# s1*conj(s2).  The baseline angle is defined as the angle of antenna2
# above the horizontal line extending from antenna1 towards the side
# of the SAR look direction.  Thus, if the baseline angle minus the
# look angle is less than -pi/2 or greater than pi/2, the topographic
# height increases with increasing elevation.  The units of
# BASELINEANGLE_RAD are radians.
BASELINE		150.0
BASELINEANGLE_DEG	225.0
#BASELINEANGLE_RAD	3.92699

# If the BPERP parameter is given, the baseline angle is taken to be
# equal to the look angle (mod pi) at midswath, and the length of the
# baseline is set accordingly.  Particular attention must be paid to
# the sign of this parameter--it should be negative if increasing
# phase implies increasing topographic height.  
#BPERP		-150.0

# The transmit mode should be either REPEATPASS or PINGPONG if both
# antennas transmitted and both received (REPEATPASS and PINGPONG have
# the same effect); the transmit mode should be SINGLEANTENNATRANSMIT
# if only one antenna was used to transmit while both antennas
# received.  In single-antenna-transmit mode, the baseline is
# effectively halved.  This parameter is ignored for cost modes other
# than topography.
TRANSMITMODE	REPEATPASS

# Slant range from platform to first range bin in input data file
# (double, meters).  Be sure to modify this parameter if the input 
# file is extracted from a larger scene.  The parameter does not need 
# to be modified is snaphu is unwrapping only a subset of the input file.
NEARRANGE	831000.0

# Slant range and azimuth pixel spacings of input interferogram after
# any multilook averaging.  This is not the same as the resolution.
# (double, meters).
DR		8.0
DA		20.0

# Single-look slant range and azimuth resolutions.  This is not the
# same as the pixel spacing.  (double, meters).
RANGERES	10.0
AZRES		6.0

# Wavelength (double, meters).
LAMBDA		0.0565647

# Number of real (not necessarily independent) looks taken in range and
# azimuth to form the input interferogram (long).  
NLOOKSRANGE	1
NLOOKSAZ	5

# Number of looks (assumed independent) from nonspatial averaging (long).
NLOOKSOTHER     1

# Equivalent number of independent looks (double, dimensionless) that were
# used to generate correlation file if one is specified.  This parameter
# is ignored if the correlation data are generated by the interferogram
# and amplitude data.
#
# The equivalent number of independent looks is approximately equal to the 
# real number of looks divided by the product of range and azimuth 
# resolutions, and multiplied by the product of the single-look range and 
# azimuth pixel spacings.  It is about 0.53 times the number of real looks 
# for ERS data processed without windowing.
NCORRLOOKS	23.8

# Number of looks that should be taken in range and azimuth for estimating
# the correlation coefficient from the interferogram and the amplitude 
# data.  These numbers must be larger than NLOOKSRANGE and NLOOKSAZ.
# The actual numbers used may be different since we prefer odd integer
# multiples of NLOOKSRANGE and NLOOKSAZ (long).  These numbers are ignored
# if a separate correlation file is given as input.
NCORRLOOKSRANGE	3
NCORRLOOKSAZ	15


###############################
# Scattering model parameters #
###############################

# Threshold brightness (normalized) for layover height integration 
# (double, dimensionless)
LAYMINEI	1.25


##################################
# Decorrelation model parameters #
##################################

# Here, rho is the magnitude of the complex correlation coefficient
# between the two observations forming the interferogram (0<=rho<=1)
# See Zebker & Villasenor, 1992

# Default value to use uniformly for true, unbiased correlation if no 
# correlation file is specified and correlation cannot be generated 
# from the available data (double). 
DEFAULTCORR	0.01

# Factor applied to expected minimum measured (biased) correlation.
# Values smaller than the threshold rhominfactor*rho0 are assumed to
# come from zero statistical correlation because of estimator bias (double).
# This is used only in topo mode; for defo mode, use DEFOTHRESHFACTOR.
RHOMINFACTOR	1.3


########################
# PDF model parameters #
########################

# Algorithm costs are based on the negative log pdf:
#
#   cost = -log(f(phi | EI, rho))

# Factor applied to range layover probability density to get azimuth
# layover probability density (double).  
AZDZFACTOR	0.99 

# Ratio of layover probability density to peak probability density
# for non-layover slopes expected (double).
LAYCONST	0.9


###############################
# Deformation mode parameters #
###############################

# Factor applied to range discontinuity probability density to get 
# corresponding value for azimuth (double).
DEFOAZDZFACTOR	1.0

# Factor applied to rho0 to get threshold for whether or not phase
# discontinuity is possible (double).  rho0 is the expected, biased 
# correlation measure if true correlation is 0.
DEFOTHRESHFACTOR 1.2

# Maximum phase discontinuity likely (double).  Units are radians or cycles.
# If abrupt phase discontinuities are not expected, this paramter can be 
# set to zero.
DEFOMAX_CYCLE	1.2
#DEFOMAX_RAD	7.5398

# Ratio of phase discontinuity probability density to peak probability
# density expected for discontinuity-possible pixel differences (double).
# Value of 1 means zero cost for discontinuity, 0 means infinite cost.
DEFOCONST	0.9


########################
# Algorithm parameters #
########################

# Maximum flow increment (long) for solver.  Not the same as maximum 
# flow possible.
MAXFLOW		4

# Scaling constant factor applied to double precision costs to get 
# integer costs (double).
COSTSCALE	100.0

# End of snaphu configuration file