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ReadSu.m
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ReadSu.m
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% ReadSu : Reads a SU formatted file (Seismic Unix)
%
% Call :
% [Data,SuTraceHeaders,SuHeader]=ReadSu(filename);
%
% To read in big endian format (default):
% [Data,SuTraceHeaders,SuHeader]=ReadSu(filename,'endian','b');
% To read in little endian format :
% [Data,SuTraceHeaders,SuHeader]=ReadSu(filename,'endian','l');
%
%
% To read in trace data as 'int32' :
% [Data,SuTraceHeaders,SuHeader]=ReadSu(filename,'DataFormat','int32');
% To read time slice 0.5<t<5 :
% [Data,SuTraceHeaders,SuHeader]=ReadSu(filename,'trange',.5,3);
% Skip every 5th trace :
% [Data,SuTraceHeaders,SuHeader]=ReadSu(filename,'jump',5);
% Read data in a CDP header range : 5000<cdp<5800
% (change cdp to any other valid TraceHeader value)
% [Data,SuTraceHeaders,SuHeader]=ReadSu(filename,'minmax','cdp'5000,5800);
%
% Combine any combination of the above
% [Data,SuTraceHeaders,SuHeader]=ReadSu(filename,'jump',1,'minmax','cdp',5300,5400);
%
%
%
% (C) 2001-2004 Thomas Mejer Hansen, tmh@gfy.ku.dk/thomas@cultpenguin.com
%
% This program is free software; you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation; either version 2 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program; if not, write to the Free Software
% Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
%
%
%
%
% 0.1 : INitial Release
% 0.2 : Added SkipData var, to skip reading of data.
% 0.3 : May 01, 2002
% Added ability to read in ever 'jump' traces.
% Added ability to read in time range.
% Added abiliy to read in header range (ex. mincdp to maxcdp).
%
function [Data,SuTraceHeaders,SuHeader]=ReadSu(filename,varargin);
dsf=[];
if ~(exist(filename)==2'),
SegymatVerbose([mfilename,' : ', filename,' does not exist !'],0)
Data=[];SuTraceHeaders=[];SuHeader=[];HeaderInfo=[];
return
end
% SET THE NEXT FLAG TO 1, IF YOU ARE SURE ALL TRACES HAVE THE SAME LENGT
% THIS WILL GREATLT INCREASE READING WHEN USING 'JUMP'
FixedTraceLength=1;
% NEXT TWO LINES TO ENUSRE THAT VARARGIN CAN BE PASSED TO FUNCTION
if nargin==2
% CALL USING VARARGIN
local_nargin=1+length(varargin{1});
varargin=varargin{1};
else
% DIRECT CALL
local_nargin=length(varargin);
end
%
% HERE SHOULD BE A CALL TO A DEFAULT SEGY HEADER !!!!
%
SegyHeader.SegyFormatRevisionNumber=1;
SegyHeader.DataSampleFormat=5;
SegyHeader.Rev=GetSegyHeaderBasics;
% TRANSFORM VARARGING INTO PARAMETERS
cargin=1;
while (cargin<local_nargin)
if strcmp(varargin{cargin},'endian')
cargin=cargin+1;
eval(['endian=char(varargin{cargin});'])
if strcmp(endian,'b'),SegymatVerbose(['Reading BIG ENDIAN STYLE'],0);end
if strcmp(endian,'l'),SegymatVerbose(['Reading LITTLE ENDIAN STYLE'],0);end
end
if strcmp(varargin{cargin},'DataFormat')
cargin=cargin+1;
eval(['DataFormat=char(varargin{cargin});'])
if strcmp(DataFormat,'float32'),
SegyHeader.DataSampleFormat=5; % IEEE
end
if strcmp(DataFormat,'int32'),
SegyHeader.DataSampleFormat=2; % 4 Byte, two's
% complement integer
end
if strcmp(DataFormat,'int16'),
SegyHeader.DataSampleFormat=3; % 2 Byte, two's
% complement integer
end
if strcmp(DataFormat,'int8'),
SegyHeader.DataSampleFormat=8; % 2 Byte, two's
% complement integer
end
SegymatVerbose(['DataFormat : ',num2str(SegyHeader.DataSampleFormat)])
end
if strcmp(varargin{cargin},'dsf')
cargin=cargin+1;
eval(['dsf=',num2str(varargin{cargin}),';']);
SegymatVerbose(['USING Data Sample Format : dsf=',num2str(dsf)])
end
if strcmp(varargin{cargin},'jump')
cargin=cargin+1;
eval(['jump=',num2str(varargin{cargin}),';']);
SegymatVerbose(['JUMP : Read only every ',num2str(jump),'th trace'])
end
if strcmp(varargin{cargin},'minmax')
cargin=cargin+1;
eval(['header=''',varargin{cargin},''';']);
cargin=cargin+1;
eval(['headermin=',num2str(varargin{cargin}),';']);
cargin=cargin+1;
eval(['headermax=',num2str(varargin{cargin}),';']);
SegymatVerbose(['MIN MAX : Using header ',header,' from ',num2str(headermin),' to ',num2str(headermax)])
end
if strcmp(varargin{cargin},'trange')
cargin=cargin+1;
eval(['tmin=',num2str(varargin{cargin}),';']);
cargin=cargin+1;
eval(['tmax=',num2str(varargin{cargin}),';']);
SegymatVerbose(['TRANGE : tmin=',num2str(tmin),' tmax=',num2str(tmax)])
end
cargin=cargin+1;
end
%
% MAYBE DATA FORMATS CAN VARY ?
% but for now we use float32 if nothing else is set
%
if exist('SegyHeader')==0,
SegyHeader.DataSampleFormat=5; % IEEE
end
if isempty(dsf)==0,
SegyHeader.DataSampleFormat=dsf;
end
%
% SU DATA CAN BE EITHER BIG OR SMALL ENDIAN
% DEFAULT IS BIG ENDIAN
%
if exist('endian')==0,
segyid = fopen(filename,'r'); % USE LOCAL BUTE ORDER AS DEFAULT
else
segyid = fopen(filename,'r',endian);
endian
end
if ~(exist(filename)==2'),
SegymatVerbose([mfilename,' : ', filename,' does not exist !'])
Data=[];SegyTraceHeaders=[];SegyHeader=[];
return
end
if exist('SkipData','var')==0,
SkipData=0; % [0] READ ONLY HEADER VALUES, [1] READ IN ALL DATA
end
if SkipData==1, SegymatVerbose(['Not reading data - headers only']), end
% SEGY HEADER FORMAT INFO
Revision=SegyHeader.SegyFormatRevisionNumber;
if Revision>0, Revision=1; end
Format=SegyHeader.Rev(Revision+1).DataSampleFormat(SegyHeader.DataSampleFormat).name;
BPS=SegyHeader.Rev(Revision+1).DataSampleFormat(SegyHeader.DataSampleFormat).bps;
SegymatVerbose([mfilename,' : ',Format],2)
% GET SIZE OF FILE
fseek(segyid,0,'eof'); DataEnd=ftell(segyid);
fseek(segyid,0,'bof'); % Go to the beginning of the file
%txt=['SegyRevision ',sprintf('%0.4g',Revision),', ',Format,'(',num2str(SegyHeader.DataSampleFormat),')'];
txt=[Format,'(',num2str(SegyHeader.DataSampleFormat),')'];
%hw=waitbar(0,['Reading SU-file -',txt]);
traceinfile=0;
outtrace=0;
existJump=exist('jump');
existHeader=exist('header');
existtmin=exist('tmin');
existtmax=exist('tmax');
t0=now;
tlast=t0;
pos0=ftell(segyid);
ntraces = -1;
tic;
while (~(ftell(segyid)>=DataEnd))
traceinfile=traceinfile+1;
usetrace=1;
if traceinfile==2
ntraces=DataEnd/ftell(segyid);
end
ishow=100;
itime=2; % Min time between verbose info to screen in seconds
t_since_last=(now-tlast)*24*3600; % Time in seconds since last screen update
%t_since_last=1;
if (((traceinfile/ishow)==round(traceinfile/ishow))&(t_since_last>itime)),
tnow=now;
tlast=tnow;
posnow=ftell(segyid);
tend=t0+DataEnd.*(tnow-t0)./(posnow-pos0);
tleft=(tend-tnow)*3600*24;
txt=sprintf('Reading trace %d/%d, (%5.0fs left) (est end %s)',traceinfile,ntraces,tleft,datestr(tend));
toc_old=toc;
SegymatVerbose(txt,-1)
end
%if exist('jump')
if existJump==1;
if (traceinfile/jump)~=round(traceinfile/jump), usetrace=0; end
end
if ((usetrace==0)&(FixedTraceLength==1)&(exist('ns')==1))
skip=240+(SegyHeader.BytesPerSample/8)*ns;
fseek(segyid,skip,'cof');
else
% Read Trace Header
SingleSuTraceHeader=GetSegyTraceHeader(segyid);
ns=SingleSuTraceHeader.ns;
% IF HEADER MIN MAX HAS BEEN CHOSEN, THEN CHECK THAT TRACE IS GOOD ENOUGH
if ((existHeader==1)&(usetrace==1))
headervalue=getfield(SingleSuTraceHeader,header);
if ((headervalue<headermin)|(headervalue>headermax))
usetrace=0;
end
end
if usetrace==1;
% Read Segy Trace Data
SkipData=0;
else
SkipData=1;
end
SingleSuData.data=GetSegyTraceData(segyid,SingleSuTraceHeader.ns,SegyHeader,SkipData);
end % END READ TRACE OR NO FIXED LENGTH
if (usetrace==1)
%% IF TIME RANGE IS SPECIFIED, THEN EXTRACT THIS
if (existtmin)&(existtmax)
% NEXT LINE SHOULD CONSIDER THAT ns in Trace and Segy Header could vary !!!
origtrange=[1:1:SingleSuTraceHeader.ns].*SingleSuTraceHeader.dt./1e+6 + SingleSuTraceHeader.DelayRecordingTime./1e+3;
gooddata=find(origtrange>tmin & origtrange<tmax);
SingleSuData.data=SingleSuData.data(gooddata);
% CHECK NEXT LINE TAHT DelatRec... is in micro seconds
SingleSuTraceHeader.DelayRecordingTime=tmin;
SingleSuTraceHeader.ns=length(gooddata);
ns=length(gooddata); % for use below
end
outtrace=outtrace+1;
SuTraceHeaders(outtrace)=SingleSuTraceHeader;
SuData(outtrace).data=SingleSuData.data;
% keyboard
end
% waitbar(ftell(segyid)/DataEnd,hw);
end
%close(hw)
SegymatVerbose([mfilename,' : Elapsed time ',num2str(toc)],2);
ns=SuTraceHeaders(1).ns;
dt=SuTraceHeaders(1).dt;
nt=length(SuData);
% DefaultSegyHeader
SuHeader=SegyHeader;
SuHeader.ns=ns;
SuHeader.nsOrig=ns;
SuHeader.dt=dt;
SuHeader.dtOrig=dt;
SuHeader.FixedLengthTraceFlag=1; % CHECK THAT THIS IS TRUE
SuHeader.SegyFormatRevisionNumber=1;
SuHeader.NumberOfExtTextualHeaders=0;
Data=zeros(ns,nt);
try
for it=1:nt
Data(:,it)=SuData(it).data;
end
catch
SegymatVerbose([mfilename,' Could not collect data in one matrix - check byte order'])
end
%[HeaderInfo]=TraceheaderToInfo(SuTraceHeaders);
return