TwoDVariation.java
- /* Copyright 2002-2024 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.gnss.antenna;
- import org.hipparchus.util.FastMath;
- import org.hipparchus.util.MathUtils;
- /**
- * Interpolator for 2D phase center variation data.
- *
- * @author Luc Maisonobe
- * @since 9.2
- */
- public class TwoDVariation implements PhaseCenterVariationFunction {
- /** Start polar angle. */
- private final double polarStart;
- /** Step between grid points. */
- private final double polarStep;
- /** Step between grid points. */
- private final double azimuthStep;
- /** Sampled phase center variations. */
- private final double[][] variations;
- /** Simple constructor.
- * @param polarStart start polar angle
- * @param polarStep between grid points
- * @param azimuthStep step between grid points
- * @param variations sampled phase center variations
- */
- public TwoDVariation(final double polarStart, final double polarStep,
- final double azimuthStep, final double[][] variations) {
- this.polarStart = polarStart;
- this.polarStep = polarStep;
- this.azimuthStep = azimuthStep;
- this.variations = new double[variations.length][];
- for (int i = 0; i < variations.length; ++i) {
- this.variations[i] = variations[i].clone();
- }
- }
- /** {@inheritDoc} */
- @Override
- public double value(final double polarAngle, final double azimuthAngle) {
- // find surrounding points
- final double az = MathUtils.normalizeAngle(azimuthAngle, FastMath.PI);
- final int iBase = (int) FastMath.floor(az / azimuthStep);
- final int i = FastMath.max(0, FastMath.min(variations.length - 2, iBase));
- final int jBase = (int) FastMath.floor((polarAngle - polarStart) / polarStep);
- final int j = FastMath.max(0, FastMath.min(variations[i].length - 2, jBase));
- final double aInf = i * azimuthStep;
- final double aSup = aInf + azimuthStep;
- final double pInf = polarStart + j * polarStep;
- final double pSup = pInf + polarStep;
- final double vInfInf = variations[i][j];
- final double vInfSup = variations[i][j + 1];
- final double vSupInf = variations[i + 1][j];
- final double vSupSup = variations[i + 1][j + 1];
- // bilinear interpolation
- final double vInf = ((polarAngle - pInf) * vInfSup + (pSup - polarAngle) * vInfInf) / polarStep;
- final double vSup = ((polarAngle - pInf) * vSupSup + (pSup - polarAngle) * vSupInf) / polarStep;
- return ((az - aInf) * vSup + (aSup - az) * vInf) / azimuthStep;
- }
- }