Commit 20f473aa authored by laura.gassner's avatar laura.gassner

description for tapering STF with stfinv

parent 2cee0b7d
...@@ -661,6 +661,7 @@ An example for the parameter string provided in PARA is: ...@@ -661,6 +661,7 @@ An example for the parameter string provided in PARA is:
\begin{itemize} \begin{itemize}
\item To select frequency domain least squares (fdlsq), apply offset dependent weights and a waterlevel use\\ \item To select frequency domain least squares (fdlsq), apply offset dependent weights and a waterlevel use\\
\textit{fdlsq:exp=1.0:waterlevel=0.01} \textit{fdlsq:exp=1.0:waterlevel=0.01}
\item For tapering the inverted STF add the option \textit{irtap=t1;t2;t3;t4} to the parameter string. The four values define the taper window. %It is important to use ";", because "," is used by the JSON-parser to separate variables.
\end{itemize} \end{itemize}
In most cases the frequency domain least squares engine is the best approach to find a suitable wavelet. There are also other possibilities, if you want to use those a detailed look at the libraries and the acompanying documentation provided in the folder /contrib is recommended. Here only the two main parameters for the fdlsq approach are described. In most cases the frequency domain least squares engine is the best approach to find a suitable wavelet. There are also other possibilities, if you want to use those a detailed look at the libraries and the acompanying documentation provided in the folder /contrib is recommended. Here only the two main parameters for the fdlsq approach are described.
...@@ -738,7 +739,7 @@ Default values are: ...@@ -738,7 +739,7 @@ Default values are:
TIMEWIN=0 TIMEWIN=0
\end{verbatim}}} \end{verbatim}}}
To apply time windowing in a time series the paramter TIMEWIN must set to 1. A automatic picker routine is not integrated. The point in time (picked time) for each source must be specified in separate files. The folder and file name can be set with the parameter PICKS\_FILE. The files must be named like this PICKS\_FILE\_<sourcenumber>.dat. So the number of sources must be equal to the number of files. Each file must contain the picked times for every receiver. To apply time windowing in a time series the parameter TIMEWIN must set to 1. A automatic picker routine is not integrated. The point in time (picked time) for each source must be specified in separate files. The folder and file name can be set with the parameter PICKS\_FILE. The files must be named like this PICKS\_FILE\_<sourcenumber>.dat. So the number of sources must be equal to the number of files. Each file must contain the picked times for every receiver.
The parameters TWLENGTH\_PLUS and TWLENGTH\_MINUS specify the length of the time window after (PLUS) and before (MINUS) the picked time. The unit is seconds. The damping factor GAMMA must be set individually. The parameters TWLENGTH\_PLUS and TWLENGTH\_MINUS specify the length of the time window after (PLUS) and before (MINUS) the picked time. The unit is seconds. The damping factor GAMMA must be set individually.
...@@ -798,7 +799,7 @@ SWS_TAPER_FILE=0 ...@@ -798,7 +799,7 @@ SWS_TAPER_FILE=0
SWS_TAPER_FILE_PER_SHOT=0 SWS_TAPER_FILE_PER_SHOT=0
\end{verbatim}}} \end{verbatim}}}
Different preconditioning matrices can be created and applied to the gradients (using the function \texttt{taper\_grad.c}). To apply a vertical taper one has to set the switch SWS\_TAPER\_GRAD\_VERT to one and for a horizontaltaper SWS\_TAPER\_GRAD\_HOR has to be 1. The parameters for the vertical and the horizontal window are defined by the input file paramters GRADT1, GRADT2, GRADT3 and GRADT4. Please have a look at the function \texttt{taper\_grad.c} directly to obtain more information about the actual definition of the tapers. It is also possible to apply cylindrical tapers around the source positions. This can be done by either setting the switch SWS\_TAPER\_GRAD\_SOURCES or SWS\_TAPER\_CIRCULAR\_PER\_SHOT to 1. If one uses SWS\_TAPER\_GRAD\_SOURCES=1 only the final gradients (that means the gradients obtained by the summation of the gradients of each shots) are multiplied with a taper that decreases the gradients at all shot positions. Therefore, one looses the update information at the source positions. To avoid this one can use SWS\_TAPER\_CIRCULAR\_PER\_SHOT=1. In this case the gradients of the single shots are preconditioned with a window that only decreases at the current shot position. This is done before the summation of all gradients to keep model update information also at the shot positions. The actual tapers are generated by the function \texttt{taper\_grad.c} and \texttt{taper\_grad\_shot.c}, respectively. The circular taper around the source positions decrease from a value of one at the edge of the taper to a value of zero at the source position. The shape of the decrease can be defined by an error function (SRTSHAPE=1) or a log-function (SRTSHAPE=2). The radius of the taper is defined in meter by SRTRADIUS. Note, that this radius must be at least 5 gridpoints. With the parameter FILTSIZE one can extend the region where the taper is zero around the source. The taper is set to zero in a square region of (2*FILTSIZE+1 times 2*FILTSIZE+1) gridpoints. All preconditioning matrices that are applied are saved in the par directory with the file names taper\_coeff\_vert.bin, taper\_coeff\_horz.bin and taper\_coeff\_sources.bin.\\ Different preconditioning matrices can be created and applied to the gradients (using the function \texttt{taper\_grad.c}). To apply a vertical taper one has to set the switch SWS\_TAPER\_GRAD\_VERT to one and for a horizontaltaper SWS\_TAPER\_GRAD\_HOR has to be 1. The parameters for the vertical and the horizontal window are defined by the input file parameters GRADT1, GRADT2, GRADT3 and GRADT4. Please have a look at the function \texttt{taper\_grad.c} directly to obtain more information about the actual definition of the tapers. It is also possible to apply cylindrical tapers around the source positions. This can be done by either setting the switch SWS\_TAPER\_GRAD\_SOURCES or SWS\_TAPER\_CIRCULAR\_PER\_SHOT to 1. If one uses SWS\_TAPER\_GRAD\_SOURCES=1 only the final gradients (that means the gradients obtained by the summation of the gradients of each shots) are multiplied with a taper that decreases the gradients at all shot positions. Therefore, one looses the update information at the source positions. To avoid this one can use SWS\_TAPER\_CIRCULAR\_PER\_SHOT=1. In this case the gradients of the single shots are preconditioned with a window that only decreases at the current shot position. This is done before the summation of all gradients to keep model update information also at the shot positions. The actual tapers are generated by the function \texttt{taper\_grad.c} and \texttt{taper\_grad\_shot.c}, respectively. The circular taper around the source positions decrease from a value of one at the edge of the taper to a value of zero at the source position. The shape of the decrease can be defined by an error function (SRTSHAPE=1) or a log-function (SRTSHAPE=2). The radius of the taper is defined in meter by SRTRADIUS. Note, that this radius must be at least 5 gridpoints. With the parameter FILTSIZE one can extend the region where the taper is zero around the source. The taper is set to zero in a square region of (2*FILTSIZE+1 times 2*FILTSIZE+1) gridpoints. All preconditioning matrices that are applied are saved in the par directory with the file names taper\_coeff\_vert.bin, taper\_coeff\_horz.bin and taper\_coeff\_sources.bin.\\
To apply an externally defined taper on the gradients in IFOS2D, the parameter SWS\_TAPER\_FILE has to be set to 1. Each model parameter requires a taper file which needs to be located in TAPER\_FILE\_NAME.vp for vp, in TAPER\_FILE\_NAME.vs for vs and in TAPER\_FILE\_NAME.rho for the density.\\ To apply an externally defined taper on the gradients in IFOS2D, the parameter SWS\_TAPER\_FILE has to be set to 1. Each model parameter requires a taper file which needs to be located in TAPER\_FILE\_NAME.vp for vp, in TAPER\_FILE\_NAME.vs for vs and in TAPER\_FILE\_NAME.rho for the density.\\
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