NAME

MCvfit - Monte Carlo automatic velocity picks (fit)


SYNOPSIS

MCvfit < in.H par= > out.H


INPUT PARAMETERS

stdin - sepfile
       input vscan(t,vel), can be n3>1
f_vint- sepfile
       optional interval vel file ( = vint.H )
f_verr- sepfile
       optional vel misfit error file ( = verr.H )
f_grms- sepfile
       optional rms vel guess file ( = grms.H )
f_gint- sepfile
       optional interval vel guess file ( = gint.H )
a - real
       Vrms intercept at t0
b - real
       Vrms "gradient"
c - real
       Vrms  "power" function.
nvdiv - integer
       nlayers per second.  ~20 good.
dvzmax- real
       max allowed MCvint contrast between 2 adjacent layers
v1bnd - integer
       Don`t allow trial MCvint(t) < v1bnd*Vint(t)
v2bnd - integer
       Don`t allow trial MCvint(t) > v2bnd*Vint(t)
vmina - real
       Global min a value
vminb - real
       Global min b value
vminc - real
       Global min c value
vmax - real
       global max MCvint value
vsurf - real
       near surface constant velocity
tsurf - real
       time thickness of near surface constant velocity layer
dtsurfdx-real
       allows a dipping water bottom:
       tsurf(x) = tsurf + (x-x0)*dtsurfdx.
sigma - real
       variance of random velocity perturbations.
nwalk - integer
       number of random walks.  A "random walk" starts
       with one initial model and tries many random
       steps away from that same initial model.
       The best model from one walk is used as the
       starting model for the next walk.
nrand - integer
       number of random steps per walk.
nconv - integer
       If fit is unchanged for nconv steps, go to a new walk.
       If the fit remains unchanged for nconv walks: stop.
toler - real
       If fit changes < toler, consider that no change.
       Note, a perfect fit is 1.0 (100%).
       The most critical parameters to try and optimize to get
       a better fit are:
       vmin*, nvdiv~10/20, dvzmax~0.6, sigma~dvzmax/2


DESCRIPTION

Monte Carlo fit parameters... This part randomly perturbs the starting Vint(t) model corresponding to the starting Vrms(t) model found above. These parameters refer to *interval* velocity, not Vrms!


CATEGORY

seis/velan