NAME
xyzin - routine to install z information to trace data given
x,y locations. The z data is provided in a 3 column x,y,z
flat file format. The trace data need only have x,y data in
the header. No assumption of 3D binning etc. is made.
SYNOPSIS
xyzin [ -Nntap ] [ -Ootap ] [ -Fotap ] [ -xx ] [ -yy ] [
-zz ] [ -toltol ] [ -maxtolmaxtol ] [ -z_replacec_zhw ] [
-ampamp ] [ -numnum ] [ -expexp ] [ -C ] [ -xhwc_xhw ] [
-yhwc_yhw ] [ -zhwc_zhw ] [ -V ] [ -? -h -help ]
DESCRIPTION
xyzin reads a set of x,y,z data into memory, sorts on x and
y for fast search access, then streams through the attached
USP format dataset to assign each trace a z value based on
x,y location. The z value for a given trace is interpolated
from the control data in memory using a nearest neighbor
search [ala vi3d].
xyzin gets both its data and its parameters from command
line arguments. These arguments specify the input, output,
x,y,z flat file, column indicators to communicate to the
routine which column is x, which is y and which is z, the
radius of investigation, optional maximum radius of investi-
gation, optional z replacement value to use beyond the max-
imum radius of investigation, the minimum number of points
to use in the interpolation, a distance weighting exponent,
a z scalar, a cosine weighting flag for the interpolation
weighting, mnemonic indicators to communicate to the routine
the location in the USP trace headers of the associated x,y
and z values and a verbose printout flag.
Command line arguments
-N ntap
Enter the input data set name or file immediately after
typing -N unless the input is from a pipe in which case
the -N entry must be omitted. This input file should
include the complete path name if the file resides in a
different directory. Be aware that you may NOT pipe
into this routine if you have flagged -tdfn on the
command line [see below]
-O otap
Enter the output filename immediately after typing -O.
This output file is not required when piping the output
to another process.
-F xyztap
Enter the x,y,z flatfile filename immediately after
typing -F. This in file is required, there is no
default.
-x x Enter the column number of the above flatfile associ-
ated with the x coordinate. The default is column 1.
-y y Enter the column number of the above flatfile associ-
ated with the y coordinate. The default is column 2.
-z z Enter the column number of the above flatfile associ-
ated with the z coordinate. The default is column 3.
-tol tol
Enter the radius of investigation surrounding each out-
put location. This area will be searched for input z
value locations and all those found within this area
will be distance weighted and used in the calculation
of the output z value. There is no default for this
entry and it is required. This entry also serves as
the calculation base for distance weighting. A point
lying on the control point will be assigned a weight of
unity. A point lying on a circle of radius -tol will
have a weight of zero. All values within a radius of
-tol will be summed and the total divided by the sum of
the weights. This process often results in a lower z
value than anticipated at any given function location.
The following entry -amp[] allows compensation for this
effect.
-maxtol maxtol
Enter the maximum radius of investigation surrounding
each output location. The is the maximum value that
the expanding radius search may attain. Should no data
be found by this radius then the output Z value will
take on the replacement value input on the commandline.
The default is the above radius of investigation multi-
plied by 1.e20.
-z_replace z_replacement
Enter the z value to be used when no data is found
inside the maximum radius of investigation. The
default is 0.0 .
-amp scalar
Enter any desired scalar with which to multiply the
weighted z values by. The default is unity.
-num num
In the event that extrapolation outside areas of con-
trol is required this entry allows the user to require
that a certain number of nearby control points are
always used in the extrapolation zone. Should the
number of points found within the user defined search
radius be zero then the radius will be expanded by 25
percent and the search performed again. This process
will be repeated until -num[] nearest neighbor func-
tions locations have been located within the search
radius. This parameter has an effect on the smoothness
of the transition between the controlled and uncon-
trolled zones in the output z values. The default
value is 5.
-exp exp
If you wish to use 1/r**exp type weighting of z values
within the radius of investigation [-tol[] above] then
make an entry here. If no -exp[] is flagged on the
command line then a simple 1/r type weighting will done
within the radius of investigation. This is a floating
point entry so any real exponent is possible.
-C cos
Enter the command line option -C to use a cosine bell
weighting of z values within the radius of investiga-
tion [-tol[] above]. The presence of -C on the command
line shuts off distance weighting.
-xhw c_xhw
enter the USP trace header mnemonic from which to
extract the x coordinate when reading the input data.
The default is [RcPtXC].
-yhw c_yhw
enter the USP trace header mnemonic from which to
extract the y coordinate when reading the input data.
The default is [RcPtYC].
-zhw c_zhw
enter the USP trace header mnemonic in which to install
the computed z coordinate. The default is [GrpElv].
-V Enter the command line argument '-V' to get printout of
the input x,y,z data.
-? or -h or -help
Enter the command line argument '-?' or -h or -help
to get online help. The program
terminates after the help screen is printed.
DISCUSSION
This routine is useful when you have a flat file control
dataset based solely on x,y coordinates, where x and y are
any valid index system used with your data, and you wish to
install said control to the header structure of your seismic
dataset. This routine will allow you to install the surface
to your data without requiring that you prep your data for
3D processing [such as is required with tim2hed3d]. It also
makes no assumption about the relationship between the data
in the flat file and the incoming USP datastream [such as is
required in xyz2head]. Any arbitrary set of x,y,z data may
be used to control the surface that is interpolated and fit
to the data. Each trace is treated independantly. The x
and y of the trace is determined and a z value is interpo-
lated from the control functions based on the same nearest
neighbor algorithm used in vi3d.
BUGS
Unknown
SEE ALSO
xyz2head(1) xyzin(1) tim2hed3d(1) li_di(1)
AUTHOR
P.G.A.Garossino [socon 422-3932] for Jan Kommedal AmocoUK
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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