As the Segy format is not understood the same way in all software, you might find that the Segy writer that is available in the INTGeo library does not write header values the way you expect them. Here are some hints on how this writer works and steps you can take:

How header values are retrieved

The header values that are written to disk are extracted from the ITrace interface. Specially, the ITrace.getHeader(int) method is used to retrieve each value to write on disk. The id passed as a parameter to that method identifies its matching IFieldDesc.

The tutorial only writes the INLINE and XLINE header values. If you need other header values, you need to adjust the ISeismicData.getTraceHeaderFields(int) and the ISeismicReader.getTraceHeaderFields() method to return all header values to write.

The Segy format is defined by the cgStandardSegyFormat class. The Segy writer looks up each field name in that format, and tries to find matching IFieldDesc instances in your virtual ISeismicData. Here is sample code to extract all standard header names:

import com.interactive.jgeo.seismic.data.cgHeaderFieldDesc;

import com.interactive.jgeo.seismic.data.cgHeaderFormat;

import com.interactive.jgeo.seismic.segy.cgStandardSegyFormat;

import java.util.Vector;

cgStandardSegyFormat format = new cgStandardSegyFormat();

Vector<cgHeaderFormat> formats = format.getTraceHeaderFormats();

for (cgHeaderFormat currentFormat : formats) {

Vector<cgHeaderFieldDesc> headerFields = currentFormat.getHeaderFields();

for (cgHeaderFieldDesc currentHeaderField : headerFields) {

System.out.println(currentHeaderField.getIdentifier() + ": " + currentHeaderField.getName());

}

}

This method creates this output:

200: TSSN

201: FIELD REC

202: FIELD TR

203: SHTPT ID

204: CDP

205: CDPTR

206: TRACE ID

222: VERT SUM

223: HORZ SUM

224: DATA USE

207: OFFSET

208: RCV ELEV

225: SRC ELEV

226: SRC DEPTH

227: RCV DATUM

228: SRC DATUM

229: SRC WATER DEPTH

230: RCV WATER DEPTH

231: ELEVATION SCALER

209: LOC SCALER

210: SRCX

211: SRCY

212: RCVX

213: RCVY

232: COORD UNITS

233: WEATHER VEL

234: SUBWEATHER VEL

235: SRC UPHOLE TIME

236: RCV UPHOLE TIME

237: SRC STATIC CORR

238: RCV STATIC CORR

239: TOTAL STATIC CORR

240: LAG A

241: LAG B

214: START TIME

242: MUTE START

243: MUTE END

215: SAMPLES IN TRACE

216: SAMPLE RATE

217: CDPX

218: CDPY

219: INLINE

220: XLINE

221: SHTPT NUM

244: SURF TIME SCALER

The IDs are not relevant for the field matching logic. Only the names should match exactly.

How to check your own header values

If the header values written to disk are invalid, here is sample code you can use to check that each trace has the right values:

import com.interactive.intgeoapi.data.IFieldDesc;

import com.interactive.intgeoapi.data.query.SeismicRangeQuery;

import com.interactive.intgeoapi.data.seismic.ISeismicData;

import com.interactive.intgeoapi.data.seismic.ISeismicReader;

import com.interactive.intgeoapi.data.seismic.ITrace;

ISeismicData seismicData = ...

ISeismicReader reader = seismicData.select(new SeismicRangeQuery());

ITrace firstTrace = reader.getTrace(0);

IFieldDesc inlineField = reader.getTraceHeaderField("INLINE");

Number header = firstTrace.getHeader(inlineField.getIdentifier());

System.out.println(header);

How to customize the Segy format

If all header values are correct in your virtual dataset and the final .sgy file doesn't show these values, then the format used by the Segy writer is not the format you expect. In this case, check this tutorial.