NAME
dbvec - build 3D database for use in retrieving inlines and
crosslines in an efficient and expedient manner.
SYNOPSIS
dbvec [ -Nntap ] [ -Ootap ] [ -dmindmin ] [ -dmaxdmax ] [
-ddelddel ] [ -A ] [ -stk ] [ -x1x1 ] [ -y1y1 ] [ -x2x2 ] [
-y2y2 ] [ -x3x3 ] [ -y3y3 ] [ -x4x4 ] [ -y4y4 ] [ -dxdx ] [
-dydy ] [ -hwshotc_ShtSta ] [ -hwgroupc_GrpSta ] [ -X ] [ -?
]
DESCRIPTION
dbvec builds a database of vectors on disk by reading
through all traces in the 3D data set and computing their
locations on an X-Y grid. the following header words must
be present in the input headers: SrPtXC, SrPtYC, RcPtXC, and
RcPtYC. The database information is written to disk as a
set of vectors containing the location on the original input
3D dataset(s). It is written as binary, and no, you cannot
edit it and look at the values. The database file is used
by the next step - edit3d - to retrieve the desired cells in
an inline or a crossline direction.
The basic layout of the survey is as follows:
Y
^
|
(4)|----------(1) Receiver Line
|_|_|_|_|_| (or Shot Line)
|_|_|_|_|_|
|_|_|_|_|_|
|_|_|_|_|_|
|_|_|_|_|_|
|_|_|_|_|_|
| | | | | |
(3)-----------(2)--> X
where the corners are labelled (1), (2), (3), and (4) in
clockwise order. The only must is that Corner (1) be placed
in the upper right hand corner (NorthEast) and that the
movement to Corner (2) be in the general direction of a
receiver or source line. The cell dimensions then can be
related to the group spacing and the line spacing. The ori-
gin is still at the lower left corner (Corner (3)). The
actual recorded survey may be rotated somewhat from the X-Y
coordinate system but dbvec takes care of that when calcu-
lating its bins. The only really complications occur when
the receiver lines do not align with the survey boundaries.
There are two ways to input the coordinates of the parral-
lelogram over which you want to extract sorted data: (1)
define a parrallelogram using (X1Y1, X2Y2, X3Y3, X4Y4)
corners, where the origin in closest to X1Y1, the X-axis
lies closest to the line X1-X4 (roughly corresponding to the
cross-line direction), and the Y-axis lies closest to the
line Y1-Y2 (roughly corresponding to the in-line direction),
or (2) define a line over the survey area using the either
pairs X1Y1 and X3Y3 or the pairs X4Y4 and X2Y2. In this
case a very skinny box results by using the Y-coordinates as
is and by adding and subtracting the cross-line cell dimen-
sion from the X-coordinates.
The program computes the cell numbers (bins) as below:
Y
^
|
(4)|---------------(1) Receiver Line
|29|22|15| 8| 1| (or Shot Line)
|__|__|__|__|__|
|30|23|16| 9| 2|
|__|__|__|__|__|
|31|24|17|10| 3|
|__|__|__|__|__|
|32|25|18|11| 4|
|__|__|__|__|__|
|33|26|19|12| 5|
|__|__|__|__|__|
|34|27|20|13| 6|
|__|__|__|__|__|
|35|28|21|14| 7|
|__|__|__|__|__|
(3)----------------(2)--> X
where Bin 1 = Li1,Di1; Bin 2 = Li1,Di2; etc.
dbvec 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. Thisinput 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'.
Note that you may have multiple files as input, up to
100 partitions; just input them in order on the command
line using multiple -Ndata entries (i.e., -Ndata1
-Ndata2 -Ndata3 ... ).
-O otap
Enter the output database file name immediately after
typing -O. This must be a disk file not a pipe.
BEWARE: If this file already exists the program will
overwrite the existing file. If you are doing an
append, then the file MUST already exist.
-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 group interval. No default.
-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 (clockwise recommended) from Corner 1
the first move to Corner 2 should be in the direction
of a receiver or shot line. The direction 1-2 will
always define the Y or DI direction. 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. A complete
description of the geometry is found in the Blue book
writeup for SR3D. NOTE: the x,y coordinates must
describe the entire survey that will be included in the
database.
-dx, -dy dx, dy
Enter the cell dimensions in the X (2-3 side) and Y
(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 interval; whichever side is
most closely aligned with the shots lines can be dimen-
sioned 1/2 the shot interval (or 1/2 the line spacing).
Remember when setting up the coordinate system the line
joining Corner (1) to Corner (2) should be clockwise
starting from the NE corner of the survey. If the sur-
vey is a parallelogram find the east side then choose
the upper corner as NE.
-X Enter the command line argument '-X' to output the data
in crossline order; else the data are output in inline
order.
-A Enter the command line argument '-A' in order to append
(add to) an existing database file created in a
previous dbvec step. This parameter allows the user to
create the database in stages, as the input data
becomes available. Be sure that the -Ndata command
line values only specify the files being appended, NOT
the files for the entire 3D dataset. The x,y corner
coordinates and the dx,dy cell dimensions MUST be
identical in the subsequent steps to that specified in
the original step.
-stk Enter the command line argument '-stk' in order to read
the bin center XYs from the trace header words CDPBCX
and CDPBCY, instead of computing them from the source
and receiver XYs. The default is to compute the bin
center XYs.
-hwshot c_ShtSta
Enter the trace header mnemonic associated with the
shot station indexing. This may be any valid USP trace
header. The program decodes internally the format
[float, integer etc.]. The default is to use SoPtNm.
-hwgroup c_GrpSta
Enter the trace header mnemonic associated with the
receiver station indexing. This may be any valid USP
trace header. The program decodes internally the for-
mat [float, integer etc.]. The default is to use
RecInd.
-? -h -help
Enter the command line argument '-? or -h or -help' to
get online help. The program terminates after the help
screen is printed.
EXAMPLE
dbvec -Ndata1 -Ndata2 -x11967081 -y1614502
-x21967081 -y2560340 -x31954293 -y3560340
-x41954293 -y4614502 -dx82.5 -dy55
-dmin0 -dmax20000 -ddel110 -Odbnam
where corner 1 is (1967081,614502), corner 2 is
(1967081,560340), corner 3 is (1954293,560340), and corner 4
is (1954293,614502).
To add to the existing database (dbnam), use:
dbvec -Ndata3 -Ndata4 -x11967081 -y1614502
-x21967081 -y2560340 -x31954293 -y3560340
-x41954293 -y4614502 -dx82.5 -dy55
-dmin0 -dmax20000 -ddel110 -Odbnam -A
BUGS
unknown
SEE ALSO
sr3d1
AUTHOR
This code is taken in part from program sr3d1 (Original SIS
code by Gary Ruckgaber; UNIX port done by Paul Gutowski).
Geoscientist: Don Wagner Programmer: Marilyn Miller
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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