NAME
sr3d1 - build 3D bin sort table for survey area subset or
traverse across survey area
SYNOPSIS
sr3d1 [ -Nntap ] [ -Ootap ] [ -Mmtap ] [ -Fftap ] [ -Sdtap ]
[ -dmindmin ] [ -dmaxdmax ] [ -ddelddel ] [ -Aatap ] [ -ami-
namin ] [ -amaxamax ] [ -adeladel ] [ -modemode ] [ -fold-
fold ] [ -fillfill ] [ -ntrcntrc ] [ -x1x1 ] [ -y1y1 ] [
-x2x2 ] [ -y2y2 ] [ -x3x3 ] [ -y3y3 ] [ -x4x4 ] [ -y4y4 ] [
-dxdx ] [ -dydy ] [ -ndxndx ] [ -ndyndy ] [ -xgraph ] [
-plotxy ] [ -xsd ] [ -linenline ] [ -moredata ] [ -E ] [ -X
] [ -stk ] [ -swxsrtwdx ] [ -swysrtwdy ] [ -? ]
DESCRIPTION
sr3d1 builds a sort table on disk by reading through all
traces in the 3D data set and computing their location on an
X-Y grid. The following header words must be present in the
input headers: SrPtXC, SrPtYC, RcPtXC, RcPtYC. For dealing
with stacked volumes the midpoint coords - CDPBCX & CDPBCY
[or a user defined replacement] - must be present (the oth-
ers are ignored). The sorting information is written to
disk as a table (no, you can't look at it like you can a
presort-type table) and the printout contains information
about the data set and also the resulting X-Y fold chart.
The sort table is used by the next step - sr3d2. In this
way the sorting process is analogous to the presort/sisort
operation.
The basic layout of the survey is as follows:
4 |-+-+-+-+-| 1 N
|_|_|_|_|_|
|_|_|_|_|_| W + E
|_|_|_|_|_|
|_|_|_|_|_| S
|_|_|_|_|_|
|_|_|_|_|_|
| | | | | |
3 |-+-+-+-+-| 2
where the corners are labelled (1), (2), (3), and (4). In
this example the corner nomenclature begins in the northeast
and progresses clockwise. This is completely arbitrary.
Corner 1 may be in any of the four corners. Your choice of
corner numbering has the following effect on the resulting
LI,DI indexing of your binned data:
Corner 1, defined by the coordinates [x1,y1], defines the
location of (LI,DI) = (1,1)
Progressing from Corner 1 to Corner 2, defined by the coor-
dinates [x2,y2], is in the direction of increasing inline [
DI ] index.
Progressing from Corner 1 to Corner 4, defined by the coor-
dinates [x4,y4] is in the direction of increasing crossline
[ LI ] index.
So if you wish your DI's to increment from North to South
and your LI's to increment from East to West then you would
like the above example. If, however, you wished to have
LI's incrementing from Southwest to Northeast and DI's
incrementing from Southeast to Northwest your corners would
then look like:
3 N
. .
. . . W + E
. . . .
2 . . . . S
. . . . .
. . . . .
. . . . 4
. . . .
. . .
. .
1
DI numbering will always increase in the 1 - 2 direction.
Inside the program this is referred to as the Y direction
hence the -dy[] entry corresponds to the inline bin spacing.
The LI numbering will always increase in the 1-4 direction,
which, internal to the program is associated with the X
direction. Spacing in this direction is associated with the
-dx[] command line entry. Notice that this is a little
confusing if the program internal coordinate system does not
correspond with your idea of the real world. We will prob-
ably be shortly be converting -dy to -ildm and -dx to -cldm
to reduce confusion. It hasn't happened yet for backward
compatibility reasons. Please bear with us.
There are two ways to input the coordinates of the parral-
lelogram over which you want to extract sorted data:
(1) define a parallelogram using [ (X1,Y1), (X2,Y2),
(X3,Y3), (X4,Y4) ] corners, where the line ( 1 - 4 )
roughly corresponds to the crossline direction, and the line
( 1 - 2 ) roughly corresponds to the inline direction, or
(2) define a line over the survey area using the either
pairs (X1,Y1) and (X3,Y3) or the pairs (X4,Y4) and (X2,Y2).
In this case a very skinny box results by using the Y-
coordinates as is and by adding and subtracting some multi-
ple of the cross-line cell dimension from the X-coordinates
(default multiple is 1; see -ndx[] -ndy[] below).
In fact there is a 3D equivalent of the latter operation
using presort3d to build the 3D sort table (yes, you can
look at this) and sisort3d to do the actual sorting. Why
have two sorting methods? It turns out that sr3d is useful
when one has data that basically has only (X,Y) coordi-
nates in the trace headers; presort3d/sisort3d is very fast
but requires that the data be prepped using pr3d. sr3d is
an absolute coordinate system; presort3d/sisort3d is a rela-
tive system defined by the Y-index (DI) anf the X-index
(LI).
An important piece of information in the sr3d1 printout file
will be the minima and maxima of all the X-Y trace coordi-
nates. This is critical for figuring out the corners of the
survey area to be sorted (see the X-Y input below). There-
fore it's a good idea to make two passes: the first with
generous X-Y's (below) to fully encompass the survey area;
and the second with the X-Y's close to the limits found by
the first pass. This strategy will ensure you have the
minimum number of dead cells on the sides after the actual
sort itself. Another program to assist in corner construc-
tion is swath_design which requires only Corner 1 and
information describing the inline and crossline azimuths and
bin spacings as well as the number of bins desired in each
direction. One of the nice things about swath_design is
that it outputs an xgraph format ascii file for QC purposes
and also prints the corner (x,y) information to the printout
file in the format required on the sr3d1 command line.
sr3d1 gets both its data and its parameters from command
line arguments. These arguments specify the input, output,
and the areal grid deinition.
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. Example -N/b/vsp/dummy tells the
program to look for file 'dummy' in directory '/b/vsp'.
-O otap
Enter the output sr3d1 sort table name or file immedi-
ately after typing -O. This must be disk file not a
pipe. If this file already exists the program will not
run until you explicitly remove it.
-F ftap
Enter the output nominal fold file name. This will be a
USP format file that can either be scanned or viewed
using xsd (use range scaling from 0 to the maximum fold
listed in the sr3d1 printout file ). It contains nomi-
nal fold information meaning the greatest fold attained
in each bin. Remember that fold also varies as a func-
tion of offset so you can think of this as the maximum
fold attained in any bin. The default is not to output
the fold dataset.
-S dtap
Enter the output offset distribution file name. This
will be in flat file format each line consisting of the
model spread offset (see below) and the number of input
offsets falling into that offset bin. The model spread
will be defined by the user supplied parameters below.
This file may be displayed quite easily using xgraph.
The default is not to output offset information.
-dmin dmin
Enter the minimum model spread offset. Default = 0.
-dmax dmax
Enter the maximum model spread offset. No default
-ddel ddel
Enter the model spread interval. No default.
-A atap
Enter the output azimuth distribution file name. This
will be in flat file format each line consisting of the
azimuth bin (see below) and the number of input source
- receiver azimuths falling into that bin. The azimuth
bins will be defined by the user supplied parameters
below. Default is not to output any azimuth informa-
tion.
-amin amin
Enter the minimum azimuth (deg). Default = 0.
-amax amax
Enter the maximum azimuth (deg). Default = 360.
-adel adel
Enter the azimuth bin size (deg). Default = 15.
-M mtap
If the survey coordinates are input in graphical form
enter the name of the pick file containing this info.
Pick file formats supported are plotxy, xgraph, and
xsd. In each case the first segment always corresponds
to the group locations. Following this there are one
or more segments corresponding to lines, swaths, or
boxes drawn around the surevey plan view within which
sorting is desired.
In the cases of plotxy and xgraph formats the first
step is to extract the group X-Ys from the pr3d deck.
This is easily done using the awk script grep GRUP <
pr3d.crds | awk '{print $2, $3}' > groups
Edit the file "groups" (or whatever else you want to
call it) and insert as the first line "Groups This puts
a title on the resulting plots and is necessary for
plotxy. The files are then ready for display using
plotxy and using this tool the user then can draw his
sorting lines and swaths. For xsd the picks are all
made on a time slice (presupposes you already have one)
but otherwise the principle is the same.
-mode mode
Enter the sort mode: 1= common midpoint; 2= common
receiver; 3= common source; 4= common centroid (after
previous sr3d sort); 5= common midpoint with CDP
centers (default).
-fold fold
Enter the fold. If defaulted the fold will be calcu-
lated internally thereby ascertaining that no data is
dropped during sorting. (this is probably for the
best).
-fill fill
fill = 0: output fold is reduced to the maximum live
fold computed internally; fill = 1: output records will
be padded with dead traces to achieve the fold speci-
fied above.
-ntrc ntrc
Redefine output traces per record: default = (output
fold) * (number of cells along side 2-3). Otherwise
this should be a multiple of the fold. ### find out
what really happens here and spell it out for the user.
-x1,-y1,-x2,-y2,-x3,-y3,-x4,-y4 [x1,x2,x3,x4], [y1,y2,y3,y4]
Enter the area of interest over the survey with the X-Y
coordinates (ft,m) defining the four corners of a
parallelogram on the ground. Going either clockwise or
counter clockwise from Corner 1 the first move to
Corner 2 should be in the direction of a receiver or
shot line [sail line in Marine parlance]. The direction
1-2 will always define the Y or DI direction as men-
tioned above. The DIs will always start from side 1-4
and increase in the 1-2 (Y) direction; the LIs will
always start from side 1-2 and increase in the 1-4 (X)
direction. The values must be the same units as those
given in the source, receiver, and midpoint X-Ys in the
trace headers.
-plotxy
Enter the command line argument '-plotxy' to input sur-
vey area of interst graphically using pick file gen-
erated by plotxy (using the xgraph mode).
-xgraph
Enter the command line argument '-xgraph' to input sur-
vey area of interst graphically using a segment from an
xgraph format file (X-Y pairs with a title - e.g.
"Groups - at the beginning of each segment and each
segment terminated by a null line).
-xsd Enter the command line argument '-xsd' to input survey
area of interest graphically using a segment from an
XSD format pick file. The pick file must be saved
using the proper units for X-Y.
-line nline
Enter the segment number you wish to use in the graphi-
cal input options. Default is to use the first one.
-dx, -dy dx, dy
Enter the cell dimensions in the X (crossline or 2-3
side) and Y (inline or 1-2 side) directions (ft,m).
The sides are defined to be X along side 2-3, Y along
side 1-2. Whichever side is most closely aligned with
the group lines can be dimensioned 1/2 the group inter-
val; whichever side is most closely aligned with the
shots lines can be dimensioned 1/2 the shot interval
(or 1/2 the line spacing).
-ndx ndx
For sorting along a line or narrow swath: enter the
multiple of the X cell dimension to define the width of
the swath. The default is 1 which means that you are
sorting along a line centered on a crossline cell
width.
-ndy ndy
For sorting along a line or narrow swath: enter the
multiple of the Y cell dimension to define the width of
the swath. The default is 1 which means that you are
sorting along a line centered on an inline cell width.
-moredata
Enter the command line argument '-moredata' to continue
building the sr3d1 table using additional data or to
break up the input stream into portions. This is useful
for long jobs where you might want to work around say
scheduled machine downtime. Ultimately the complete
data used in sr3d2 must be in the same sequential order
but it can be streamed as one data set.
-X Enter the command line argument '-X' to cause binned
data to be served up from sr3d2 in crossline order.
The default is to serve the data up in inline order.
This parameter is passed on to sort step sr3d2 in the
sr3d1 table.
-E Enter the command line argument '-E' to pad the box or
parallelogram outlined by the coordinates by values
that correspond to 1/2 dx & 1/2 dy. This is sometimes
useful when using the graphical mode of inputting coor-
dinates when the display of groups go right to the edge
of the plot thereby not allowing the user to completely
encompass the depth points of the suvey.
-stk Enter the command line argument '-stk' to sort stacked
volumes, i.e. you have several volumes to merge into
one super volume. The trace header word for the mid-
point bin center XYs - CDPBCX & CDPBCY [or a user
defined replacement set (see -swx[] -swy[] below) -
must exist.
-swx srtwdx
For stack option enter the trace header X-coord word to
sort on. Default = CDPBCX
-swy srtwdy
For stack option enter the trace header Y-coord word to
sort on. Default = CDPBCY
-? -h -help
Enter the command line argument '-?' -h or -help to get
online help. The program terminates after the help
screen is printed.
EXAMPLE
Sort over an area:
sr3d1 -Nindata -Osr3d.tbl -x1 1323700 -y1 200100 -x2 1323000
-y2 200100
-x3 1323000 -y3 194200 -x4 1323700 -y4 194200 -dy100 -dx50
where corner 1 is (1323700,200100), corner 2 is
(1323000,200100), corner 3 is (1323000,194200), and corner 4
is (1323700,194200). The sort order from the sr3d2 step will
be inline.
Sort along an oblique line one cell wide:
sr3d1 -Nindata -Osr3d.tbl -x11323500 -y1200100 -x31323200
-y3194200
-dx50 -dy100 -nd1
Sort within some swath defined graphically:
sr3d1 -N3d.pr3d -Otmp -dx50 -dy100 -plotxy -line3
-Mline5.plotxy
where line5.plotxy is a plotxy format file containing the
coordinates.
BUGS
unknown
SEE ALSO
sr3d2 presort3d, sisort3d, pack3d
AUTHOR
Original SIS code by Gary Ruckgaber; UNIX port done by Paul
Gutowski
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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