NAME
corners - given the overall survey corner XYs compute (1)
the bin center XYs for a rectangle defined by LIs & DIs and
(2) the corner XYs for a 1/2-bin fringe around the input
box; also checks for proper survey parallogram
SYNOPSIS
corners [ -dimindimin ] [ -dimaxdimax ] [ -liminlimin ] [
-limaxlimax ] [ -x1x1 ] [ -y1y1 ] [ -x2x2 ] [ -y2y2 ] [
-x3x3 ] [ -y3y3 ] [ -x4x4 ] [ -y4y4 ] [ -cldmcldm ] [ -ild-
mildm ] [ -P ] [ -? ]
DESCRIPTION
corners (1) computes the bin center XYs (the CDPBCY & CDPBCY
found in trace headers) of a rectangle defined by corner LI
& DI numbers within a survey area. Useful for determining
the XYs of selected lines within a survey. It is a stand-
alone program and requires no seismic input or output.
(2) computes the XYs (X1, Y1, ...) for a fringe around the
input box that is essentially 1/2-bin wide. This is useful
because of the difference between say Landmark which uses
the cell center XYs as the boundary of a survey and USP
which uses the cell outermost wall as the boundary.
corners optionally checks whether the given corner XYs form
an exact parallelogram. If it does not the differences
between the various X and Y corners is given suggesting
where the discrepency lies. After the check the program
stops.
corners gets both its data and its parameters from command
line arguments. These arguments specify the minimum and
maximum LI and DI values of the rectangle, and obverall sur-
vey dimensions. Its output goes to the terminal.
Command line arguments
x4, y4]
-x1, -y1, -x2, -y2, -x3, -y3, -x4, -
y4 [x1, y1, x2, y2, x3, y3,
Enter the area of interest over the survey with the X-Y
coordinates (ft,m) definin g the four corners of a
parallelogram on the ground. Corner 1 is always
defined t o be the northeast corner. Going either
clockwise or counter clockwise (clockwise recommended)
from Corner 1 the first move to Corner 2 should be in
the direction o f a receiver or shot line. The origin
will always be defined to be the lower left (corner 3)
of the survey. The values must be the same units as
those given in the
source, receiver, and midpoint X-Ys in the trace
headers.
-cldm cldm
Enter the crossline (along X or side 2-3) cell dimen-
sion (ft,m). For most shooting
geometries this will be 1/2 the line or group spacing
depending on the orientatio n of side 2-3 with respect
to the receiver lines. The sides are defined to be X al
ong side 1-4 (roughly cross-line direction), Y along
side 1-2 (roughly in-line dir ection). Remember when
setting up the coordinate system the line joining
Corner (1 ) to Corner (2) should be in the direction of
a receiver or shot line. No default.
-ildm ildm
Enter the inline (along Y or side 1-2) cell dimension
(ft,m). For most recording g eometries this will be 1/2
the line or group spacing depending on the orientation
of side 1-2 with respect to the receiver lines. The
sides are defined to be X alon g side 1-4 (roughly
cross-line direction), Y along side 1-2 (roughly in-
line direc tion). Remember when setting up the coordi-
nate system the line joining Corner (1) to Corner (2)
should be in the direction of a receiver or shot line.
No default.
-limin limin
Enter the minimum LI index for which to compute bin
center X & Y. Default = 1
-limax limax
Enter the maximum LI index for which to compute bin
center X & Y. Default = none
-dimin dimin
Enter the minimum DI index for which to compute bin
center X & Y. Default = 1
-dimax dimax
Enter the maximum DI index for which to compute bin
center X & Y. Default = none
-P Enter the command line argument '-P' to check whther
the input survey corner coordinates form an exact
parallelogram. If they do not differences between the
various corner X and Y values are printed suggesting
where corrections can be made. For some floating point
cell dimensions it may be possible to get close but
never exact. After the check the program stops.
-? Enter the command line argument '-?' to get online
help. The program terminates after the help screen is
printed.
EXAMPLE
The first example demonstrates the primary function of the
program:
corners -x1 15500 -y1 15500 -x2 300 -y2 15500 -x3 300 \
-y3 300 -x4 15500 -y4 300 -ildm 200 -cldm 200 \
-limin 5 -dimin 5 -limax 10 -dimax 10
which results in the following printout to the terminal:
X1, Y1 = 15500 15500
X2, Y2 = 300 15500
X3, Y3 = 300 300
X4, Y4 = 15500 300
inline (side 1-2) dimension = 200.000
xline (side 2-3) dimension = 200.000
number cells along 1-2 = 76
number cells along 2-3 = 76
minimum LI = 5
minimum DI = 5
maximum LI = 10
maximum DI = 10
CORNER BIN CENTER XYs contained with input box:
Corner 1 [limin:dimin] - X 14600 Y 14600
Corner 2 [limin:dimax] - X 13600 Y 14600
Corner 3 [limax:dimax] - X 13600 Y 13600
Corner 4 [limax:dimin] - X 14600 Y 13600
CORNER XYs for 1/2-bin fringe around input box:
Corner 1 [+fringe] - X 15600 Y 15600
Corner 2 [+fringe] - X 200 Y 15600
Corner 3 [+fringe] - X 200 Y 200
Corner 4 [+fringe] - X 15600 Y 200
The next example demonstrates the option which checks for
parallelogram consistency of the input survey corner XYs
corners -x1 15500 -y1 15600 -x2 300 -y2 15500 -x3 300 \
-y3 300 -x4 15500 -y4 300 -ildm 200 -cldm 200 -P
which results in the following printout to the terminal
Input coordinates do not form an exact parallelogram
IX= 234090000
(IX3-IX2) * (IX3-IX2) + (IY3-IY2) * (IY3-IY2)= 231040000
(IX4-IX1) = 0
(IX3-IX2) = 0
(IY4-IY1) = -15300
(IY3-IY2) = -15200
IY= 231050000
(IX4-IX3) * (IX4-IX3) + (IY4-IY3) * (IY4-IY3)= 231040000
(IX2-IX1) = -15200
(IX4-IX3) = 15200
(IY4-IY3) = 0
(IY2-IY1) = -100
where it looks like either the Y1 or Y2 values is off by 100
units (it's really Y1)
BUGS
you must put values on the command line for all input param-
eters (no defaults).
SEE ALSO
sr3d1
AUTHOR
Paul Gutowski, EPTG, 422-3146, zprg03@trc.amoco.com
COPYRIGHT
copyright 2001, Amoco Production Company
All Rights Reserved
an affiliate of BP America Inc.
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