GRGSFormatReader.java
/* Copyright 2002-2023 CS GROUP
* 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.forces.gravity.potential;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.text.ParseException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.hipparchus.util.FastMath;
import org.hipparchus.util.Precision;
import org.orekit.annotation.DefaultDataContext;
import org.orekit.data.DataContext;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitMessages;
import org.orekit.errors.OrekitParseException;
import org.orekit.time.AbsoluteDate;
import org.orekit.time.DateComponents;
import org.orekit.time.TimeScale;
import org.orekit.utils.Constants;
/** Reader for the GRGS gravity field format.
*
* <p> This format was used to describe various gravity fields at GRGS (Toulouse).
*
* <p> The proper way to use this class is to call the {@link GravityFieldFactory}
* which will determine which reader to use with the selected gravity field file.</p>
*
* @see GravityFields
* @author Luc Maisonobe
*/
public class GRGSFormatReader extends PotentialCoefficientsReader {
/** Patterns for lines (the last pattern is repeated for all data lines). */
private static final Pattern[] LINES;
/** Flag for Earth data. */
private static final int EARTH = 0x1;
/** Flag for degree/order. */
private static final int LIMITS = 0x2;
/** Flag for coefficients. */
private static final int COEFFS = 0x4;
/** Reference date. */
private AbsoluteDate referenceDate;
/** Converter from triangular to flat form. */
private Flattener dotFlattener;
/** Secular drift of the cosine coefficients. */
private double[] cDot;
/** Secular drift of the sine coefficients. */
private double[] sDot;
static {
// sub-patterns
final String real = "[-+]?\\d?\\.\\d+[eEdD][-+]\\d\\d";
final String sep = ")\\s*(";
// regular expression for header lines
final String[] header = {
"^\\s*FIELD - .*$",
"^\\s+AE\\s+1/F\\s+GM\\s+OMEGA\\s*$",
"^\\s*(" + real + sep + real + sep + real + sep + real + ")\\s*$",
"^\\s*REFERENCE\\s+DATE\\s+:\\s+(\\d+)\\.0+\\s*$",
"^\\s*MAXIMAL\\s+DEGREE\\s+:\\s+(\\d+)\\s.*$",
"^\\s*L\\s+M\\s+DOT\\s+CBAR\\s+SBAR\\s+SIGMA C\\s+SIGMA S(\\s+LIB)?\\s*$"
};
// regular expression for data lines
final String data = "^([ 0-9]{3})([ 0-9]{3})( |DOT)\\s*(" +
real + sep + real + sep + real + sep + real +
")(\\s+[0-9]+)?\\s*$";
// compile the regular expressions
LINES = new Pattern[header.length + 1];
for (int i = 0; i < header.length; ++i) {
LINES[i] = Pattern.compile(header[i]);
}
LINES[LINES.length - 1] = Pattern.compile(data);
}
/** Simple constructor.
*
* <p>This constructor uses the {@link DataContext#getDefault() default data context}.
*
* @param supportedNames regular expression for supported files names
* @param missingCoefficientsAllowed if true, allows missing coefficients in the input data
* @see #GRGSFormatReader(String, boolean, TimeScale)
*/
@DefaultDataContext
public GRGSFormatReader(final String supportedNames, final boolean missingCoefficientsAllowed) {
this(supportedNames, missingCoefficientsAllowed,
DataContext.getDefault().getTimeScales().getTT());
}
/**
* Simple constructor.
*
* @param supportedNames regular expression for supported files names
* @param missingCoefficientsAllowed if true, allows missing coefficients in the input
* data
* @param timeScale to use when parsing dates.
* @since 10.1
*/
public GRGSFormatReader(final String supportedNames,
final boolean missingCoefficientsAllowed,
final TimeScale timeScale) {
super(supportedNames, missingCoefficientsAllowed, timeScale);
reset();
}
/** {@inheritDoc} */
public void loadData(final InputStream input, final String name)
throws IOException, ParseException, OrekitException {
// reset the indicator before loading any data
reset();
// FIELD - GRIM5, VERSION : C1, november 1999
// AE 1/F GM OMEGA
//0.63781364600000E+070.29825765000000E+030.39860044150000E+150.72921150000000E-04
//REFERENCE DATE : 1997.00
//MAXIMAL DEGREE : 120 Sigmas calibration factor : .5000E+01 (applied)
//L M DOT CBAR SBAR SIGMA C SIGMA S
// 2 0DOT 0.13637590952454E-10 0.00000000000000E+00 .143968E-11 .000000E+00
// 3 0DOT 0.28175700027753E-11 0.00000000000000E+00 .496704E-12 .000000E+00
// 4 0DOT 0.12249148508277E-10 0.00000000000000E+00 .129977E-11 .000000E+00
// 0 0 .99999999988600E+00 .00000000000000E+00 .153900E-09 .000000E+00
// 2 0 -0.48416511550920E-03 0.00000000000000E+00 .204904E-10 .000000E+00
Flattener flattener = null;
int dotDegree = -1;
int dotOrder = -1;
int flags = 0;
int lineNumber = 0;
double[] c0 = null;
double[] s0 = null;
double[] c1 = null;
double[] s1 = null;
try (BufferedReader r = new BufferedReader(new InputStreamReader(input, StandardCharsets.UTF_8))) {
for (String line = r.readLine(); line != null; line = r.readLine()) {
++lineNumber;
// match current header or data line
final Matcher matcher = LINES[FastMath.min(LINES.length, lineNumber) - 1].matcher(line);
if (!matcher.matches()) {
throw new OrekitParseException(OrekitMessages.UNABLE_TO_PARSE_LINE_IN_FILE,
lineNumber, name, line);
}
if (lineNumber == 3) {
// header line defining ae, 1/f, GM and Omega
setAe(parseDouble(matcher.group(1)));
setMu(parseDouble(matcher.group(3)));
flags |= EARTH;
} else if (lineNumber == 4) {
// header line containing the reference date
referenceDate = toDate(
new DateComponents(Integer.parseInt(matcher.group(1)), 1, 1));
} else if (lineNumber == 5) {
// header line defining max degree
final int degree = FastMath.min(getMaxParseDegree(), Integer.parseInt(matcher.group(1)));
final int order = FastMath.min(getMaxParseOrder(), degree);
flattener = new Flattener(degree, order);
c0 = buildFlatArray(flattener, missingCoefficientsAllowed() ? 0.0 : Double.NaN);
s0 = buildFlatArray(flattener, missingCoefficientsAllowed() ? 0.0 : Double.NaN);
c1 = buildFlatArray(flattener, 0.0);
s1 = buildFlatArray(flattener, 0.0);
flags |= LIMITS;
} else if (lineNumber > 6) {
// data line
final int i = Integer.parseInt(matcher.group(1).trim());
final int j = Integer.parseInt(matcher.group(2).trim());
if (flattener.withinRange(i, j)) {
if ("DOT".equals(matcher.group(3).trim())) {
// store the secular drift coefficients
parseCoefficient(matcher.group(4), flattener, c1, i, j, "Cdot", name);
parseCoefficient(matcher.group(5), flattener, s1, i, j, "Sdot", name);
dotDegree = FastMath.max(dotDegree, i);
dotOrder = FastMath.max(dotOrder, j);
} else {
// store the constant coefficients
parseCoefficient(matcher.group(4), flattener, c0, i, j, "C", name);
parseCoefficient(matcher.group(5), flattener, s0, i, j, "S", name);
}
}
flags |= COEFFS;
}
}
}
if (flags != (EARTH | LIMITS | COEFFS)) {
String loaderName = getClass().getName();
loaderName = loaderName.substring(loaderName.lastIndexOf('.') + 1);
throw new OrekitException(OrekitMessages.UNEXPECTED_FILE_FORMAT_ERROR_FOR_LOADER,
name, loaderName);
}
if (missingCoefficientsAllowed()) {
// ensure at least the (0, 0) element is properly set
if (Precision.equals(c0[flattener.index(0, 0)], 0.0, 0)) {
c0[flattener.index(0, 0)] = 1.0;
}
}
// resize secular drift arrays
if (dotDegree >= 0) {
dotFlattener = new Flattener(dotDegree, dotOrder);
cDot = new double[dotFlattener.arraySize()];
sDot = new double[dotFlattener.arraySize()];
for (int n = 0; n <= dotDegree; ++n) {
for (int m = 0; m <= FastMath.min(n, dotOrder); ++m) {
cDot[dotFlattener.index(n, m)] = c1[flattener.index(n, m)];
sDot[dotFlattener.index(n, m)] = s1[flattener.index(n, m)];
}
}
}
setRawCoefficients(true, flattener, c0, s0, name);
setTideSystem(TideSystem.UNKNOWN);
setReadComplete(true);
}
/** Reset instance before read.
* @since 11.1
*/
private void reset() {
setReadComplete(false);
referenceDate = null;
dotFlattener = null;
cDot = null;
sDot = null;
}
/** {@inheritDoc}
* <p>
* GRGS fields may include time-dependent parts which are taken into account
* in the returned provider.
* </p>
*/
public RawSphericalHarmonicsProvider getProvider(final boolean wantNormalized,
final int degree, final int order) {
// get the constant part
RawSphericalHarmonicsProvider provider = getBaseProvider(wantNormalized, degree, order);
if (dotFlattener != null) {
// add the secular trend layer
final double scale = 1.0 / Constants.JULIAN_YEAR;
final Flattener rescaledFlattener = new Flattener(FastMath.min(degree, dotFlattener.getDegree()),
FastMath.min(order, dotFlattener.getOrder()));
provider = new SecularTrendSphericalHarmonics(provider, referenceDate, rescaledFlattener,
rescale(scale, wantNormalized, rescaledFlattener, dotFlattener, cDot),
rescale(scale, wantNormalized, rescaledFlattener, dotFlattener, sDot));
}
return provider;
}
}