SP3Writer.java
/* Copyright 2002-2024 Luc Maisonobe
* Licensed to CS GROUP (CS) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* CS licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.orekit.files.sp3;
import java.io.IOException;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import org.hipparchus.util.FastMath;
import org.orekit.gnss.TimeSystem;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.DateTimeComponents;
import org.orekit.time.TimeScale;
import org.orekit.time.TimeScales;
import org.orekit.utils.CartesianDerivativesFilter;
/** Writer for SP3 file.
* @author Luc Maisonobe
* @since 12.0
*/
public class SP3Writer {
/** End Of Line. */
private static final String EOL = System.lineSeparator();
/** Prefix for accuracy lines. */
private static final String ACCURACY_LINE_PREFIX = "++ ";
/** Prefix for comment lines. */
private static final String COMMENT_LINE_PREFIX = "/* ";
/** Format for accuracy base lines. */
private static final String ACCURACY_BASE_FORMAT = "%%f %10.7f %12.9f %14.11f %18.15f%n";
/** Constant additional parameters lines. */
private static final String ADDITIONAL_PARAMETERS_LINE = "%i 0 0 0 0 0 0 0 0 0";
/** Format for one 2 digits integer field. */
private static final String TWO_DIGITS_INTEGER = "%2d";
/** Format for one 3 digits integer field. */
private static final String THREE_DIGITS_INTEGER = "%3d";
/** Format for one 14.6 digits float field. */
private static final String FOURTEEN_SIX_DIGITS_FLOAT = "%14.6f";
/** Format for three blanks field. */
private static final String THREE_BLANKS = " ";
/** Time system default line. */
private static final String TIME_SYSTEM_DEFAULT = "%c cc cc ccc ccc cccc cccc cccc cccc ccccc ccccc ccccc ccccc";
/** Destination of generated output. */
private final Appendable output;
/** Output name for error messages. */
private final String outputName;
/** Set of time scales used for parsing dates. */
private final TimeScales timeScales;
/** Simple constructor.
* @param output destination of generated output
* @param outputName output name for error messages
* @param timeScales set of time scales used for parsing dates
*/
public SP3Writer(final Appendable output, final String outputName, final TimeScales timeScales) {
this.output = output;
this.outputName = outputName;
this.timeScales = timeScales;
}
/** Write a SP3 file.
* @param sp3 SP3 file to write
* @exception IOException if an I/O error occurs.
*/
public void write(final SP3 sp3)
throws IOException {
sp3.validate(false, outputName);
writeHeader(sp3.getHeader());
// set up iterators for all satellites
final CoordinatesIterator[] iterators = new CoordinatesIterator[sp3.getSatelliteCount()];
int k = 0;
for (final Map.Entry<String, SP3Ephemeris> entry : sp3.getSatellites().entrySet()) {
iterators[k++] = new CoordinatesIterator(entry.getValue());
}
final TimeScale timeScale = sp3.getHeader().getTimeSystem().getTimeScale(timeScales);
for (AbsoluteDate date = earliest(iterators); !date.equals(AbsoluteDate.FUTURE_INFINITY); date = earliest(iterators)) {
// epoch
final DateTimeComponents dtc = date.getComponents(timeScale);
output.append(String.format(Locale.US, "* %4d %2d %2d %2d %2d %11.8f%n",
dtc.getDate().getYear(),
dtc.getDate().getMonth(),
dtc.getDate().getDay(),
dtc.getTime().getHour(),
dtc.getTime().getMinute(),
dtc.getTime().getSecond()));
for (final CoordinatesIterator iter : iterators) {
final SP3Coordinate coordinate;
if (iter.pending != null &&
FastMath.abs(iter.pending.getDate().durationFrom(date)) <= 0.001 * sp3.getHeader().getEpochInterval()) {
// the pending coordinate date matches current epoch
coordinate = iter.pending;
iter.advance();
} else {
// the pending coordinate does not match current epoch
coordinate = SP3Coordinate.DUMMY;
}
// position
writePosition(sp3.getHeader(), iter.id, coordinate);
if (sp3.getHeader().getFilter() != CartesianDerivativesFilter.USE_P) {
// velocity
writeVelocity(sp3.getHeader(), iter.id, coordinate);
}
}
}
output.append("EOF").
append(EOL);
}
/** Find earliest date in ephemerides.
* @param iterators ephemerides iterators
* @return earliest date in iterators
*/
private AbsoluteDate earliest(final CoordinatesIterator[] iterators) {
AbsoluteDate date = AbsoluteDate.FUTURE_INFINITY;
for (final CoordinatesIterator iter : iterators) {
if (iter.pending != null && iter.pending.getDate().isBefore(date)) {
date = iter.pending.getDate();
}
}
return date;
}
/** Write position.
* @param header file header
* @param satId satellite id
* @param coordinate coordinate
* @exception IOException if an I/O error occurs.
*/
private void writePosition(final SP3Header header, final String satId, final SP3Coordinate coordinate)
throws IOException {
final StringBuilder lineBuilder = new StringBuilder();
// position
lineBuilder.append(String.format(Locale.US, "P%3s%14.6f%14.6f%14.6f",
satId,
SP3Utils.POSITION_UNIT.fromSI(coordinate.getPosition().getX()),
SP3Utils.POSITION_UNIT.fromSI(coordinate.getPosition().getY()),
SP3Utils.POSITION_UNIT.fromSI(coordinate.getPosition().getZ())));
// clock
lineBuilder.append(String.format(Locale.US, FOURTEEN_SIX_DIGITS_FLOAT,
SP3Utils.CLOCK_UNIT.fromSI(coordinate.getClockCorrection())));
// position accuracy
if (coordinate.getPositionAccuracy() == null) {
lineBuilder.append(THREE_BLANKS).
append(THREE_BLANKS).
append(THREE_BLANKS);
} else {
lineBuilder.append(' ');
lineBuilder.append(String.format(Locale.US, TWO_DIGITS_INTEGER,
SP3Utils.indexAccuracy(SP3Utils.POSITION_ACCURACY_UNIT, header.getPosVelBase(),
coordinate.getPositionAccuracy().getX())));
lineBuilder.append(' ');
lineBuilder.append(String.format(Locale.US, TWO_DIGITS_INTEGER,
SP3Utils.indexAccuracy(SP3Utils.POSITION_ACCURACY_UNIT, header.getPosVelBase(),
coordinate.getPositionAccuracy().getY())));
lineBuilder.append(' ');
lineBuilder.append(String.format(Locale.US, TWO_DIGITS_INTEGER,
SP3Utils.indexAccuracy(SP3Utils.POSITION_ACCURACY_UNIT, header.getPosVelBase(),
coordinate.getPositionAccuracy().getZ())));
}
// clock accuracy
lineBuilder.append(' ');
if (Double.isNaN(coordinate.getClockAccuracy())) {
lineBuilder.append(THREE_BLANKS);
} else {
lineBuilder.append(String.format(Locale.US, THREE_DIGITS_INTEGER,
SP3Utils.indexAccuracy(SP3Utils.CLOCK_ACCURACY_UNIT, header.getClockBase(),
coordinate.getClockAccuracy())));
}
// events
lineBuilder.append(' ');
lineBuilder.append(coordinate.hasClockEvent() ? 'E' : ' ');
lineBuilder.append(coordinate.hasClockPrediction() ? 'P' : ' ');
lineBuilder.append(' ');
lineBuilder.append(' ');
lineBuilder.append(coordinate.hasOrbitManeuverEvent() ? 'M' : ' ');
lineBuilder.append(coordinate.hasOrbitPrediction() ? 'P' : ' ');
output.append(lineBuilder.toString().trim()).append(EOL);
}
/** Write velocity.
* @param header file header
* @param satId satellite id
* @param coordinate coordinate
* @exception IOException if an I/O error occurs.
*/
private void writeVelocity(final SP3Header header, final String satId, final SP3Coordinate coordinate)
throws IOException {
final StringBuilder lineBuilder = new StringBuilder();
// velocity
lineBuilder.append(String.format(Locale.US, "V%3s%14.6f%14.6f%14.6f",
satId,
SP3Utils.VELOCITY_UNIT.fromSI(coordinate.getVelocity().getX()),
SP3Utils.VELOCITY_UNIT.fromSI(coordinate.getVelocity().getY()),
SP3Utils.VELOCITY_UNIT.fromSI(coordinate.getVelocity().getZ())));
// clock rate
lineBuilder.append(String.format(Locale.US, FOURTEEN_SIX_DIGITS_FLOAT,
SP3Utils.CLOCK_RATE_UNIT.fromSI(coordinate.getClockRateChange())));
// velocity accuracy
if (coordinate.getVelocityAccuracy() == null) {
lineBuilder.append(THREE_BLANKS).
append(THREE_BLANKS).
append(THREE_BLANKS);
} else {
lineBuilder.append(' ');
lineBuilder.append(String.format(Locale.US, TWO_DIGITS_INTEGER,
SP3Utils.indexAccuracy(SP3Utils.VELOCITY_ACCURACY_UNIT, header.getPosVelBase(),
coordinate.getVelocityAccuracy().getX())));
lineBuilder.append(' ');
lineBuilder.append(String.format(Locale.US, TWO_DIGITS_INTEGER,
SP3Utils.indexAccuracy(SP3Utils.VELOCITY_ACCURACY_UNIT, header.getPosVelBase(),
coordinate.getVelocityAccuracy().getY())));
lineBuilder.append(' ');
lineBuilder.append(String.format(Locale.US, TWO_DIGITS_INTEGER,
SP3Utils.indexAccuracy(SP3Utils.VELOCITY_ACCURACY_UNIT, header.getPosVelBase(),
coordinate.getVelocityAccuracy().getZ())));
}
// clock rate accuracy
lineBuilder.append(' ');
if (Double.isNaN(coordinate.getClockRateAccuracy())) {
lineBuilder.append(THREE_BLANKS);
} else {
lineBuilder.append(String.format(Locale.US, THREE_DIGITS_INTEGER,
SP3Utils.indexAccuracy(SP3Utils.CLOCK_RATE_ACCURACY_UNIT, header.getClockBase(),
coordinate.getClockRateAccuracy())));
}
output.append(lineBuilder.toString().trim()).append(EOL);
}
/** Write header.
* @param header SP3 header to write
* @exception IOException if an I/O error occurs.
*/
private void writeHeader(final SP3Header header)
throws IOException {
final TimeScale timeScale = header.getTimeSystem().getTimeScale(timeScales);
final DateTimeComponents dtc = header.getEpoch().getComponents(timeScale);
final StringBuilder dataUsedBuilder = new StringBuilder();
for (final DataUsed du : header.getDataUsed()) {
if (dataUsedBuilder.length() > 0) {
dataUsedBuilder.append('+');
}
dataUsedBuilder.append(du.getKey());
}
final String dataUsed = dataUsedBuilder.length() <= 5 ?
dataUsedBuilder.toString() :
DataUsed.MIXED.getKey();
// header first line: version, epoch...
output.append(String.format(Locale.US, "#%c%c%4d %2d %2d %2d %2d %11.8f %7d %5s %5s %3s %4s%n",
header.getVersion(),
header.getFilter() == CartesianDerivativesFilter.USE_P ? 'P' : 'V',
dtc.getDate().getYear(),
dtc.getDate().getMonth(),
dtc.getDate().getDay(),
dtc.getTime().getHour(),
dtc.getTime().getMinute(),
dtc.getTime().getSecond(),
header.getNumberOfEpochs(),
dataUsed,
header.getCoordinateSystem(),
header.getOrbitTypeKey(),
header.getAgency()));
// header second line : dates
output.append(String.format(Locale.US, "## %4d %15.8f %14.8f %5d %15.13f%n",
header.getGpsWeek(),
header.getSecondsOfWeek(),
header.getEpochInterval(),
header.getModifiedJulianDay(),
header.getDayFraction()));
// list of satellites
final List<String> satellites = header.getSatIds();
output.append(String.format(Locale.US, "+ %3d ", satellites.size()));
int lines = 0;
int column = 9;
int remaining = satellites.size();
for (final String satId : satellites) {
output.append(String.format(Locale.US, "%3s", satId));
--remaining;
column += 3;
if (column >= 60 && remaining > 0) {
// finish line
output.append(EOL);
++lines;
// start new line
output.append("+ ");
column = 9;
}
}
while (column < 60) {
output.append(' ').
append(' ').
append('0');
column += 3;
}
output.append(EOL);
++lines;
while (lines++ < 5) {
// write extra lines to have at least 85 satellites
output.append("+ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0").
append(EOL);
}
// general accuracy
output.append(ACCURACY_LINE_PREFIX);
lines = 0;
column = 9;
remaining = satellites.size();
for (final String satId : satellites) {
final double accuracy = header.getAccuracy(satId);
final int accuracyExp = SP3Utils.indexAccuracy(SP3Utils.POSITION_ACCURACY_UNIT, SP3Utils.POS_VEL_BASE_ACCURACY, accuracy);
output.append(String.format(Locale.US, THREE_DIGITS_INTEGER, accuracyExp));
--remaining;
column += 3;
if (column >= 60 && remaining > 0) {
// finish line
output.append(EOL);
++lines;
// start new line
output.append(ACCURACY_LINE_PREFIX);
column = 9;
}
}
while (column < 60) {
output.append(' ').
append(' ').
append('0');
column += 3;
}
output.append(EOL);
++lines;
while (lines++ < 5) {
// write extra lines to have at least 85 satellites
output.append("++ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0").
append(EOL);
}
// type
if (header.getVersion() == 'a') {
output.append(TIME_SYSTEM_DEFAULT).append(EOL);
} else {
final TimeSystem ts = header.getTimeSystem().getKey() == null ?
TimeSystem.UTC :
header.getTimeSystem();
output.append(String.format(Locale.US, "%%c %1s cc %3s ccc cccc cccc cccc cccc ccccc ccccc ccccc ccccc%n",
header.getType().getKey(), ts.getKey()));
}
output.append(TIME_SYSTEM_DEFAULT).append(EOL);
// entries accuracy
output.append(String.format(Locale.US, ACCURACY_BASE_FORMAT,
header.getPosVelBase(), header.getClockBase(), 0.0, 0.0));
output.append(String.format(Locale.US, ACCURACY_BASE_FORMAT,
0.0, 0.0, 0.0, 0.0));
// additional parameters
output.append(ADDITIONAL_PARAMETERS_LINE).append(EOL);
output.append(ADDITIONAL_PARAMETERS_LINE).append(EOL);
// comments
int count = 0;
for (final String comment : header.getComments()) {
++count;
output.append(COMMENT_LINE_PREFIX).append(comment).append(EOL);
}
while (count < 4) {
// add dummy comments to get at least the four comments specified for versions a, b and c
++count;
output.append(COMMENT_LINE_PREFIX).append(EOL);
}
}
/** Iterator for coordinates. */
private static class CoordinatesIterator {
/** Satellite ID. */
private final String id;
/** Iterator over segments. */
private Iterator<SP3Segment> segmentsIterator;
/** Iterator over coordinates. */
private Iterator<SP3Coordinate> coordinatesIterator;
/** Pending coordinate. */
private SP3Coordinate pending;
/** Simple constructor.
* @param ephemeris underlying ephemeris
*/
CoordinatesIterator(final SP3Ephemeris ephemeris) {
this.id = ephemeris.getId();
this.segmentsIterator = ephemeris.getSegments().iterator();
this.coordinatesIterator = null;
advance();
}
/** Advance to next coordinates.
*/
private void advance() {
while (coordinatesIterator == null || !coordinatesIterator.hasNext()) {
// we have exhausted previous segment
if (segmentsIterator != null && segmentsIterator.hasNext()) {
coordinatesIterator = segmentsIterator.next().getCoordinates().iterator();
} else {
// we have exhausted the ephemeris
segmentsIterator = null;
pending = null;
return;
}
}
// retrieve the next entry
pending = coordinatesIterator.next();
}
}
}