/*====================================================================*\   This program scans a velocity volume in SU format and extracts   Landmark horizons bounding a threshold value.   The output format corresponds to a default Landmark format for   importing X-Y-Z triples.   Reginald H. Beardsley                            rhb@acm.org\*====================================================================*/#include "su.h"#include "segy.h"#include "par.h"#define MAX_SURFACES 100char *sdoc = "\n""Required parameters:                     \n";main(int argc, char **argv ){   FILE *infp=stdin;   FILE* bfp[MAX_SURFACES];   FILE* tfp[MAX_SURFACES];   char filename[PATH_MAX];   float base[MAX_SURFACES];   float top[MAX_SURFACES];   float zscale = 1.0;   float salt=4500;   float dt;   float x;   float y;   float line;   float xline;   int i;   int j;   int k;   int n;   int p;   int in_salt;   segytrace tr;   memset( tfp ,0 ,sizeof(tfp) );   memset( bfp ,0 ,sizeof(tfp) );   /*----------------*/   /* get parameters */   /*----------------*/   initargs(argc,argv);   askdoc(1);   getparfloat("salt",&salt);   getparfloat("zscale",&zscale);   while( fgettr( infp ,&tr ) ){      x = tr.sx;      y = tr.sy;      line  = tr.fldr;      xline = tr.ep;      dt    = tr.dt * zscale;      j = 0;      k = 0;      in_salt = 0;      /*-------------------------------------*/      /* search for salt-sediment interfaces */      /*-------------------------------------*/      for( i=0; i<tr.ns; i++ ){         if( !in_salt && tr.data[i] >= salt ){            top[j++] = i*dt;            in_salt = 1;         }else if( in_salt && tr.data[i] < salt ){            base[k++] = i*dt;            in_salt = 0;         }      }/*--------------------------------------------------------------------*\  Note that the geometrical relationship defined here places salt  between top[j] & base[j].  This is different from what Zhiming Li  defined in his programs.\*--------------------------------------------------------------------*/      /*-------------------------------*/      /* write out X-Y-Z to top  files */      /*-------------------------------*/      for( i=0; i<j; i++ ){         if( !tfp[i] ){            sprintf( filename ,"top_%d.xyz" ,i+1 );            if( !(tfp[i] = fopen( filename ,"w" )) ){               err( "Failed to open %s\n" ,filename );            }         }         fprintf( tfp[i] ,"%20s "   ,""      );         fprintf( tfp[i] ,"%9.1f "  ,line    );         fprintf( tfp[i] ,"%9.1f "  ,xline   );         fprintf( tfp[i] ,"%11.1f " ,x       );         fprintf( tfp[i] ,"%11.1f " ,y       );         fprintf( tfp[i] ,"%11.2f " ,top[i]  );         fprintf( tfp[i] ,"\n" );         }      /*--------------------------------*/      /* write out X-Y-Z to base  files */      /*--------------------------------*/      for( i=0; i<k; i++ ){         if( !bfp[i] ){            sprintf( filename ,"base_%d.xyz" ,i+1 );            if( !(bfp[i] = fopen( filename ,"w" )) ){               err( "Failed to open %s\n" ,filename );            }         }         fprintf( bfp[i] ,"%20s "   ,""      );         fprintf( bfp[i] ,"%9.1f "  ,line    );         fprintf( bfp[i] ,"%9.1f "  ,xline   );         fprintf( bfp[i] ,"%11.1f " ,x       );         fprintf( bfp[i] ,"%11.1f " ,y       );         fprintf( bfp[i] ,"%11.2f " ,base[i] );         fprintf( bfp[i] ,"\n" );         }   }   return 0;}