How sioseis process geom
calculates rp numbers
According the process geom documentation (22
October 2002)
The shot is assigned an
X-coordinate by adding (type 1) or multiplying
(type 2) DFLS (distance from
the last shot) to the X-coordinate of the
shot. Each receiver is assigned an
X-coordinate by adding the
shot-receiver distance to the
shot X-coordinate. The RP X-coordinate
is calculated by assuming the
RP is halfway between the shot and
receiver. The RP number is the RP X-coordinate divided
by DBRPS
(distance between RPs) and
truncating to an integer. The
coordinate of
the first shot of the job is
the shot number (from the header) times the
distance from the previous
shot. i.e.
xs = FLOAT(lhead(3)) * dfls
rx = FLOAT(lhead(10))
xr = xs + rx
xrp = (xr + xs) / 2.
lhead(6) = NINT( xrp/dbrps )
Type 2 geom example where the
first shot is shot 9711, dfls = 50,
dbrps = 6.25, range to trace
1 = -6168:
xs = 9711. * 50. = 485550.
rx = -6168.
xr = 485550. -6168. = 479382
xrp = (485550 + 479382.) / 2.
= 964932/2 = 482466
rp_number = 482466 / 6.25 =
77194.56 = 77195
Type 9 geom example where the
first shot is 33000, dbrps = 6.25, and
range to trace 1 = -6168:
(type 9 geometry sets dfls =
1. for the first shot)
xs = 33000.
rx = -6168.
xr = 33000 -6168 = 26832
xrp = (33000 + 26832) / 2 =
59832 / 2 = 29916
rp_number = 29916 / 6.25 =
4786.56 = 4787
Type 9 geom example where the
first shot is 58309, dbrps = 6.25, and
range to trace 1 = -6168:
xs = 58309
xr = 58309. -6168. = 52141.
xrp = (58309. + 52141.) / 2.
= 110450. / 2. = 55225.
rp_number = 55225. / 6.25 =
8836