SHMFormatReader.java
/* Copyright 2002-2016 CS Systèmes d'Information
* Licensed to CS Systèmes d'Information (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.text.ParseException;
import java.util.ArrayList;
import java.util.List;
import java.util.Locale;
import org.hipparchus.util.FastMath;
import org.hipparchus.util.Precision;
import org.orekit.errors.OrekitException;
import org.orekit.errors.OrekitMessages;
import org.orekit.time.DateComponents;
import org.orekit.utils.Constants;
/** Reader for the SHM gravity field format.
*
* <p> This format was used to describe the gravity field of EIGEN models
* published by the GFZ Potsdam up to 2003. It was then replaced by
* {@link ICGEMFormatReader ICGEM format}. The SHM format is described in
* <a href="http://www.gfz-potsdam.de/grace/results/"> Potsdam university
* website</a>.
*
* <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 GravityFieldFactory
* @author Fabien Maussion
*/
public class SHMFormatReader extends PotentialCoefficientsReader {
/** First field labels. */
private static final String GRCOEF = "GRCOEF";
/** Second field labels. */
private static final String GRCOF2 = "GRCOF2";
/** Drift coefficients labels. */
private static final String GRDOTA = "GRDOTA";
/** Reference date. */
private DateComponents referenceDate;
/** Secular drift of the cosine coefficients. */
private final List<List<Double>> cDot;
/** Secular drift of the sine coefficients. */
private final List<List<Double>> sDot;
/** Simple constructor.
* @param supportedNames regular expression for supported files names
* @param missingCoefficientsAllowed if true, allows missing coefficients in the input data
*/
public SHMFormatReader(final String supportedNames, final boolean missingCoefficientsAllowed) {
super(supportedNames, missingCoefficientsAllowed);
referenceDate = null;
cDot = new ArrayList<List<Double>>();
sDot = new ArrayList<List<Double>>();
}
/** {@inheritDoc} */
public void loadData(final InputStream input, final String name)
throws IOException, ParseException, OrekitException {
// reset the indicator before loading any data
setReadComplete(false);
referenceDate = null;
cDot.clear();
sDot.clear();
boolean normalized = false;
TideSystem tideSystem = TideSystem.UNKNOWN;
final BufferedReader r = new BufferedReader(new InputStreamReader(input, "UTF-8"));
boolean okEarth = false;
boolean okSHM = false;
boolean okCoeffs = false;
double[][] c = null;
double[][] s = null;
String line = r.readLine();
if ((line != null) &&
"FIRST ".equals(line.substring(0, 6)) &&
"SHM ".equals(line.substring(49, 56))) {
for (line = r.readLine(); line != null; line = r.readLine()) {
if (line.length() >= 6) {
final String[] tab = line.split("\\s+");
// read the earth values
if ("EARTH".equals(tab[0])) {
setMu(parseDouble(tab[1]));
setAe(parseDouble(tab[2]));
okEarth = true;
}
// initialize the arrays
if ("SHM".equals(tab[0])) {
final int degree = FastMath.min(getMaxParseDegree(), Integer.parseInt(tab[1]));
final int order = FastMath.min(getMaxParseOrder(), degree);
c = buildTriangularArray(degree, order, missingCoefficientsAllowed() ? 0.0 : Double.NaN);
s = buildTriangularArray(degree, order, missingCoefficientsAllowed() ? 0.0 : Double.NaN);
final String lowerCaseLine = line.toLowerCase(Locale.US);
normalized = lowerCaseLine.contains("fully normalized");
if (lowerCaseLine.contains("exclusive permanent tide")) {
tideSystem = TideSystem.TIDE_FREE;
} else {
tideSystem = TideSystem.UNKNOWN;
}
okSHM = true;
}
// fill the arrays
if (GRCOEF.equals(line.substring(0, 6)) || GRCOF2.equals(tab[0]) || GRDOTA.equals(tab[0])) {
final int i = Integer.parseInt(tab[1]);
final int j = Integer.parseInt(tab[2]);
if (i < c.length && j < c[i].length) {
if (GRDOTA.equals(tab[0])) {
// store the secular drift coefficients
extendListOfLists(cDot, i, j, 0.0);
extendListOfLists(sDot, i, j, 0.0);
parseCoefficient(tab[3], cDot, i, j, "Cdot", name);
parseCoefficient(tab[4], sDot, i, j, "Sdot", name);
// check the reference date (format yyyymmdd)
final DateComponents localRef = new DateComponents(Integer.parseInt(tab[7].substring(0, 4)),
Integer.parseInt(tab[7].substring(4, 6)),
Integer.parseInt(tab[7].substring(6, 8)));
if (referenceDate == null) {
// first reference found, store it
referenceDate = localRef;
} else if (!referenceDate.equals(localRef)) {
throw new OrekitException(OrekitMessages.SEVERAL_REFERENCE_DATES_IN_GRAVITY_FIELD,
referenceDate, localRef, name);
}
} else {
// store the constant coefficients
parseCoefficient(tab[3], c, i, j, "C", name);
parseCoefficient(tab[4], s, i, j, "S", name);
okCoeffs = true;
}
}
}
}
}
}
if (missingCoefficientsAllowed() && c.length > 0 && c[0].length > 0) {
// ensure at least the (0, 0) element is properly set
if (Precision.equals(c[0][0], 0.0, 0)) {
c[0][0] = 1.0;
}
}
if (!(okEarth && okSHM && okCoeffs)) {
String loaderName = getClass().getName();
loaderName = loaderName.substring(loaderName.lastIndexOf('.') + 1);
throw new OrekitException(OrekitMessages.UNEXPECTED_FILE_FORMAT_ERROR_FOR_LOADER,
name, loaderName);
}
setRawCoefficients(normalized, c, s, name);
setTideSystem(tideSystem);
setReadComplete(true);
}
/** Get a provider for read spherical harmonics coefficients.
* <p>
* SHM fields do include time-dependent parts which are taken into account
* in the returned provider.
* </p>
* @param wantNormalized if true, the provider will provide normalized coefficients,
* otherwise it will provide un-normalized coefficients
* @param degree maximal degree
* @param order maximal order
* @return a new provider
* @exception OrekitException if the requested maximal degree or order exceeds the
* available degree or order or if no gravity field has read yet
* @since 6.0
*/
public RawSphericalHarmonicsProvider getProvider(final boolean wantNormalized,
final int degree, final int order)
throws OrekitException {
// get the constant part
RawSphericalHarmonicsProvider provider = getConstantProvider(wantNormalized, degree, order);
if (!cDot.isEmpty()) {
// add the secular trend layer
final double[][] cArray = toArray(cDot);
final double[][] sArray = toArray(sDot);
rescale(1.0 / Constants.JULIAN_YEAR, true, cArray, sArray, wantNormalized, cArray, sArray);
provider = new SecularTrendSphericalHarmonics(provider, referenceDate, cArray, sArray);
}
return provider;
}
}