271 lines
9.8 KiB
C++
271 lines
9.8 KiB
C++
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// Boost.Geometry
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// Copyright (c) 2018 Adeel Ahmad, Islamabad, Pakistan.
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// Contributed and/or modified by Adeel Ahmad,
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// as part of Google Summer of Code 2018 program.
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// This file was modified by Oracle on 2018-2020.
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// Modifications copyright (c) 2018-2020 Oracle and/or its affiliates.
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// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle
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// Use, modification and distribution is subject to the Boost Software License,
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// Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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// This file is converted from GeographicLib, https://geographiclib.sourceforge.io
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// GeographicLib is originally written by Charles Karney.
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// Author: Charles Karney (2008-2017)
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// Last updated version of GeographicLib: 1.49
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// Original copyright notice:
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// Copyright (c) Charles Karney (2008-2017) <charles@karney.com> and licensed
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// under the MIT/X11 License. For more information, see
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// https://geographiclib.sourceforge.io
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#ifndef BOOST_GEOMETRY_FORMULAS_KARNEY_DIRECT_HPP
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#define BOOST_GEOMETRY_FORMULAS_KARNEY_DIRECT_HPP
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#include <boost/array.hpp>
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#include <boost/math/constants/constants.hpp>
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#include <boost/math/special_functions/hypot.hpp>
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#include <boost/geometry/formulas/flattening.hpp>
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#include <boost/geometry/formulas/result_direct.hpp>
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#include <boost/geometry/util/condition.hpp>
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#include <boost/geometry/util/math.hpp>
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#include <boost/geometry/util/normalize_spheroidal_coordinates.hpp>
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#include <boost/geometry/util/series_expansion.hpp>
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namespace boost { namespace geometry { namespace formula
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{
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namespace se = series_expansion;
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/*!
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\brief The solution of the direct problem of geodesics on latlong coordinates,
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after Karney (2011).
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\author See
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- Charles F.F Karney, Algorithms for geodesics, 2011
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https://arxiv.org/pdf/1109.4448.pdf
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*/
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template <
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typename CT,
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bool EnableCoordinates = true,
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bool EnableReverseAzimuth = false,
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bool EnableReducedLength = false,
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bool EnableGeodesicScale = false,
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size_t SeriesOrder = 8
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>
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class karney_direct
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{
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static const bool CalcQuantities = EnableReducedLength || EnableGeodesicScale;
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static const bool CalcCoordinates = EnableCoordinates || CalcQuantities;
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static const bool CalcRevAzimuth = EnableReverseAzimuth || CalcCoordinates || CalcQuantities;
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public:
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typedef result_direct<CT> result_type;
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template <typename T, typename Dist, typename Azi, typename Spheroid>
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static inline result_type apply(T const& lo1,
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T const& la1,
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Dist const& distance,
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Azi const& azimuth12,
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Spheroid const& spheroid)
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{
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result_type result;
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CT lon1 = lo1;
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CT const lat1 = la1;
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Azi azi12 = azimuth12;
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math::normalize_azimuth<degree, Azi>(azi12);
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CT const c0 = 0;
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CT const c1 = 1;
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CT const c2 = 2;
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CT const b = CT(get_radius<2>(spheroid));
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CT const f = formula::flattening<CT>(spheroid);
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CT const one_minus_f = c1 - f;
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CT const two_minus_f = c2 - f;
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CT const n = f / two_minus_f;
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CT const e2 = f * two_minus_f;
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CT const ep2 = e2 / math::sqr(one_minus_f);
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CT sin_alpha1, cos_alpha1;
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math::sin_cos_degrees<CT>(azi12, sin_alpha1, cos_alpha1);
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// Find the reduced latitude.
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CT sin_beta1, cos_beta1;
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math::sin_cos_degrees<CT>(lat1, sin_beta1, cos_beta1);
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sin_beta1 *= one_minus_f;
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math::normalize_unit_vector<CT>(sin_beta1, cos_beta1);
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cos_beta1 = (std::max)(c0, cos_beta1);
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// Obtain alpha 0 by solving the spherical triangle.
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CT const sin_alpha0 = sin_alpha1 * cos_beta1;
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CT const cos_alpha0 = boost::math::hypot(cos_alpha1, sin_alpha1 * sin_beta1);
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CT const k2 = math::sqr(cos_alpha0) * ep2;
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CT const epsilon = k2 / (c2 * (c1 + math::sqrt(c1 + k2)) + k2);
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// Find the coefficients for A1 by computing the
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// series expansion using Horner scehme.
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CT const expansion_A1 = se::evaluate_A1<SeriesOrder>(epsilon);
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// Index zero element of coeffs_C1 is unused.
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se::coeffs_C1<SeriesOrder, CT> const coeffs_C1(epsilon);
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// Tau is an integration variable.
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CT const tau12 = distance / (b * (c1 + expansion_A1));
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CT const sin_tau12 = sin(tau12);
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CT const cos_tau12 = cos(tau12);
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CT sin_sigma1 = sin_beta1;
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CT sin_omega1 = sin_alpha0 * sin_beta1;
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CT cos_sigma1, cos_omega1;
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cos_sigma1 = cos_omega1 = sin_beta1 != c0 || cos_alpha1 != c0 ? cos_beta1 * cos_alpha1 : c1;
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math::normalize_unit_vector<CT>(sin_sigma1, cos_sigma1);
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CT const B11 = se::sin_cos_series(sin_sigma1, cos_sigma1, coeffs_C1);
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CT const sin_B11 = sin(B11);
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CT const cos_B11 = cos(B11);
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CT const sin_tau1 = sin_sigma1 * cos_B11 + cos_sigma1 * sin_B11;
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CT const cos_tau1 = cos_sigma1 * cos_B11 - sin_sigma1 * sin_B11;
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// Index zero element of coeffs_C1p is unused.
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se::coeffs_C1p<SeriesOrder, CT> const coeffs_C1p(epsilon);
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CT const B12 = - se::sin_cos_series
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(sin_tau1 * cos_tau12 + cos_tau1 * sin_tau12,
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cos_tau1 * cos_tau12 - sin_tau1 * sin_tau12,
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coeffs_C1p);
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CT const sigma12 = tau12 - (B12 - B11);
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CT const sin_sigma12 = sin(sigma12);
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CT const cos_sigma12 = cos(sigma12);
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CT const sin_sigma2 = sin_sigma1 * cos_sigma12 + cos_sigma1 * sin_sigma12;
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CT const cos_sigma2 = cos_sigma1 * cos_sigma12 - sin_sigma1 * sin_sigma12;
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if (BOOST_GEOMETRY_CONDITION(CalcRevAzimuth))
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{
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CT const sin_alpha2 = sin_alpha0;
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CT const cos_alpha2 = cos_alpha0 * cos_sigma2;
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result.reverse_azimuth = atan2(sin_alpha2, cos_alpha2);
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// Convert the angle to radians.
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result.reverse_azimuth /= math::d2r<CT>();
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}
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if (BOOST_GEOMETRY_CONDITION(CalcCoordinates))
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{
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// Find the latitude at the second point.
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CT const sin_beta2 = cos_alpha0 * sin_sigma2;
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CT const cos_beta2 = boost::math::hypot(sin_alpha0, cos_alpha0 * cos_sigma2);
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result.lat2 = atan2(sin_beta2, one_minus_f * cos_beta2);
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// Convert the coordinate to radians.
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result.lat2 /= math::d2r<CT>();
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// Find the longitude at the second point.
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CT const sin_omega2 = sin_alpha0 * sin_sigma2;
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CT const cos_omega2 = cos_sigma2;
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CT const omega12 = atan2(sin_omega2 * cos_omega1 - cos_omega2 * sin_omega1,
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cos_omega2 * cos_omega1 + sin_omega2 * sin_omega1);
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se::coeffs_A3<SeriesOrder, CT> const coeffs_A3(n);
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CT const A3 = math::horner_evaluate(epsilon, coeffs_A3.begin(), coeffs_A3.end());
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CT const A3c = -f * sin_alpha0 * A3;
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se::coeffs_C3<SeriesOrder, CT> const coeffs_C3(n, epsilon);
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CT const B31 = se::sin_cos_series(sin_sigma1, cos_sigma1, coeffs_C3);
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CT const lam12 = omega12 + A3c *
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(sigma12 + (se::sin_cos_series
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(sin_sigma2,
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cos_sigma2,
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coeffs_C3) - B31));
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// Convert to radians to get the
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// longitudinal difference.
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CT lon12 = lam12 / math::d2r<CT>();
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// Add the longitude at first point to the longitudinal
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// difference and normalize the result.
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math::normalize_longitude<degree, CT>(lon1);
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math::normalize_longitude<degree, CT>(lon12);
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result.lon2 = lon1 + lon12;
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// For longitudes close to the antimeridian the result can be out
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// of range. Therefore normalize.
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// In other formulas this has to be done at the end because
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// otherwise differential quantities are calculated incorrectly.
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// But here it's ok since result.lon2 is not used after this point.
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math::normalize_longitude<degree, CT>(result.lon2);
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}
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if (BOOST_GEOMETRY_CONDITION(CalcQuantities))
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{
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// Evaluate the coefficients for C2.
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// Index zero element of coeffs_C2 is unused.
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se::coeffs_C2<SeriesOrder, CT> const coeffs_C2(epsilon);
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CT const B21 = se::sin_cos_series(sin_sigma1, cos_sigma1, coeffs_C2);
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CT const B22 = se::sin_cos_series(sin_sigma2, cos_sigma2, coeffs_C2);
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// Find the coefficients for A2 by computing the
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// series expansion using Horner scehme.
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CT const expansion_A2 = se::evaluate_A2<SeriesOrder>(epsilon);
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CT const AB1 = (c1 + expansion_A1) * (B12 - B11);
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CT const AB2 = (c1 + expansion_A2) * (B22 - B21);
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CT const J12 = (expansion_A1 - expansion_A2) * sigma12 + (AB1 - AB2);
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CT const dn1 = math::sqrt(c1 + ep2 * math::sqr(sin_beta1));
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CT const dn2 = math::sqrt(c1 + k2 * math::sqr(sin_sigma2));
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// Find the reduced length.
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result.reduced_length = b * ((dn2 * (cos_sigma1 * sin_sigma2) -
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dn1 * (sin_sigma1 * cos_sigma2)) -
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cos_sigma1 * cos_sigma2 * J12);
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// Find the geodesic scale.
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CT const t = k2 * (sin_sigma2 - sin_sigma1) *
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(sin_sigma2 + sin_sigma1) / (dn1 + dn2);
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result.geodesic_scale = cos_sigma12 +
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(t * sin_sigma2 - cos_sigma2 * J12) *
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sin_sigma1 / dn1;
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}
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return result;
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}
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};
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}}} // namespace boost::geometry::formula
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#endif // BOOST_GEOMETRY_FORMULAS_KARNEY_DIRECT_HPP
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