331 lines
9.2 KiB
C++
331 lines
9.2 KiB
C++
// Boost.Geometry (aka GGL, Generic Geometry Library)
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// Copyright (c) 2007-2011 Barend Gehrels, Amsterdam, the Netherlands.
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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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#ifndef BOOST_GEOMETRY_STRATEGIES_SPHERICAL_DISTANCE_HAVERSINE_HPP
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#define BOOST_GEOMETRY_STRATEGIES_SPHERICAL_DISTANCE_HAVERSINE_HPP
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#include <boost/geometry/core/cs.hpp>
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#include <boost/geometry/core/access.hpp>
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#include <boost/geometry/core/radian_access.hpp>
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#include <boost/geometry/util/select_calculation_type.hpp>
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#include <boost/geometry/util/promote_floating_point.hpp>
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#include <boost/geometry/strategies/distance.hpp>
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namespace boost { namespace geometry
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{
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namespace strategy { namespace distance
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{
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namespace comparable
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{
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// Comparable haversine.
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// To compare distances, we can avoid:
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// - multiplication with radius and 2.0
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// - applying sqrt
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// - applying asin (which is strictly (monotone) increasing)
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template
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<
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typename Point1,
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typename Point2 = Point1,
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typename CalculationType = void
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>
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class haversine
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{
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public :
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typedef typename promote_floating_point
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<
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typename select_calculation_type
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<
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Point1,
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Point2,
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CalculationType
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>::type
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>::type calculation_type;
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inline haversine(calculation_type const& r = 1.0)
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: m_radius(r)
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{}
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static inline calculation_type apply(Point1 const& p1, Point2 const& p2)
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{
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return calculate(get_as_radian<0>(p1), get_as_radian<1>(p1),
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get_as_radian<0>(p2), get_as_radian<1>(p2));
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}
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inline calculation_type radius() const
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{
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return m_radius;
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}
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private :
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static inline calculation_type calculate(calculation_type const& lon1,
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calculation_type const& lat1,
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calculation_type const& lon2,
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calculation_type const& lat2)
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{
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return math::hav(lat2 - lat1)
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+ cos(lat1) * cos(lat2) * math::hav(lon2 - lon1);
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}
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calculation_type m_radius;
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};
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} // namespace comparable
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/*!
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\brief Distance calculation for spherical coordinates
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on a perfect sphere using haversine
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\ingroup strategies
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\tparam Point1 \tparam_first_point
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\tparam Point2 \tparam_second_point
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\tparam CalculationType \tparam_calculation
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\author Adapted from: http://williams.best.vwh.net/avform.htm
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\see http://en.wikipedia.org/wiki/Great-circle_distance
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\note It says: <em>The great circle distance d between two
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points with coordinates {lat1,lon1} and {lat2,lon2} is given by:
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d=acos(sin(lat1)*sin(lat2)+cos(lat1)*cos(lat2)*cos(lon1-lon2))
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A mathematically equivalent formula, which is less subject
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to rounding error for short distances is:
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d=2*asin(sqrt((sin((lat1-lat2)/2))^2
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+ cos(lat1)*cos(lat2)*(sin((lon1-lon2)/2))^2))
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</em>
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\qbk{
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[heading See also]
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[link geometry.reference.algorithms.distance.distance_3_with_strategy distance (with strategy)]
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}
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*/
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template
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<
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typename Point1,
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typename Point2 = Point1,
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typename CalculationType = void
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>
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class haversine
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{
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typedef comparable::haversine<Point1, Point2, CalculationType> comparable_type;
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public :
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typedef typename services::return_type<comparable_type>::type calculation_type;
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/*!
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\brief Constructor
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\param radius radius of the sphere, defaults to 1.0 for the unit sphere
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*/
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inline haversine(calculation_type const& radius = 1.0)
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: m_radius(radius)
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{}
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/*!
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\brief applies the distance calculation
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\return the calculated distance (including multiplying with radius)
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\param p1 first point
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\param p2 second point
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*/
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inline calculation_type apply(Point1 const& p1, Point2 const& p2) const
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{
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calculation_type const a = comparable_type::apply(p1, p2);
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calculation_type const c = calculation_type(2.0) * asin(sqrt(a));
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return m_radius * c;
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}
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/*!
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\brief access to radius value
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\return the radius
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*/
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inline calculation_type radius() const
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{
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return m_radius;
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}
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private :
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calculation_type m_radius;
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};
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#ifndef DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
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namespace services
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{
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template <typename Point1, typename Point2, typename CalculationType>
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struct tag<haversine<Point1, Point2, CalculationType> >
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{
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typedef strategy_tag_distance_point_point type;
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};
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template <typename Point1, typename Point2, typename CalculationType>
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struct return_type<haversine<Point1, Point2, CalculationType> >
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{
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typedef typename haversine<Point1, Point2, CalculationType>::calculation_type type;
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};
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template <typename Point1, typename Point2, typename CalculationType, typename P1, typename P2>
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struct similar_type<haversine<Point1, Point2, CalculationType>, P1, P2>
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{
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typedef haversine<P1, P2, CalculationType> type;
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};
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template <typename Point1, typename Point2, typename CalculationType, typename P1, typename P2>
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struct get_similar<haversine<Point1, Point2, CalculationType>, P1, P2>
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{
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private :
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typedef haversine<Point1, Point2, CalculationType> this_type;
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public :
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static inline typename similar_type<this_type, P1, P2>::type apply(this_type const& input)
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{
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return haversine<P1, P2, CalculationType>(input.radius());
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}
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};
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template <typename Point1, typename Point2, typename CalculationType>
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struct comparable_type<haversine<Point1, Point2, CalculationType> >
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{
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typedef comparable::haversine<Point1, Point2, CalculationType> type;
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};
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template <typename Point1, typename Point2, typename CalculationType>
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struct get_comparable<haversine<Point1, Point2, CalculationType> >
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{
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private :
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typedef haversine<Point1, Point2, CalculationType> this_type;
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typedef comparable::haversine<Point1, Point2, CalculationType> comparable_type;
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public :
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static inline comparable_type apply(this_type const& input)
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{
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return comparable_type(input.radius());
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}
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};
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template <typename Point1, typename Point2, typename CalculationType>
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struct result_from_distance<haversine<Point1, Point2, CalculationType> >
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{
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private :
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typedef haversine<Point1, Point2, CalculationType> this_type;
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typedef typename return_type<this_type>::type return_type;
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public :
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template <typename T>
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static inline return_type apply(this_type const& , T const& value)
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{
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return return_type(value);
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}
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};
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// Specializations for comparable::haversine
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template <typename Point1, typename Point2, typename CalculationType>
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struct tag<comparable::haversine<Point1, Point2, CalculationType> >
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{
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typedef strategy_tag_distance_point_point type;
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};
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template <typename Point1, typename Point2, typename CalculationType>
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struct return_type<comparable::haversine<Point1, Point2, CalculationType> >
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{
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typedef typename comparable::haversine<Point1, Point2, CalculationType>::calculation_type type;
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};
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template <typename Point1, typename Point2, typename CalculationType, typename P1, typename P2>
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struct similar_type<comparable::haversine<Point1, Point2, CalculationType>, P1, P2>
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{
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typedef comparable::haversine<P1, P2, CalculationType> type;
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};
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template <typename Point1, typename Point2, typename CalculationType, typename P1, typename P2>
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struct get_similar<comparable::haversine<Point1, Point2, CalculationType>, P1, P2>
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{
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private :
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typedef comparable::haversine<Point1, Point2, CalculationType> this_type;
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public :
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static inline typename similar_type<this_type, P1, P2>::type apply(this_type const& input)
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{
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return comparable::haversine<P1, P2, CalculationType>(input.radius());
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}
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};
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template <typename Point1, typename Point2, typename CalculationType>
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struct comparable_type<comparable::haversine<Point1, Point2, CalculationType> >
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{
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typedef comparable::haversine<Point1, Point2, CalculationType> type;
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};
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template <typename Point1, typename Point2, typename CalculationType>
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struct get_comparable<comparable::haversine<Point1, Point2, CalculationType> >
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{
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private :
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typedef comparable::haversine<Point1, Point2, CalculationType> this_type;
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public :
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static inline this_type apply(this_type const& input)
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{
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return input;
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}
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};
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template <typename Point1, typename Point2, typename CalculationType>
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struct result_from_distance<comparable::haversine<Point1, Point2, CalculationType> >
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{
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private :
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typedef comparable::haversine<Point1, Point2, CalculationType> strategy_type;
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typedef typename return_type<strategy_type>::type return_type;
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public :
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template <typename T>
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static inline return_type apply(strategy_type const& strategy, T const& distance)
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{
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return_type const s = sin((distance / strategy.radius()) / return_type(2));
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return s * s;
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}
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};
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// Register it as the default for point-types
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// in a spherical equatorial coordinate system
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template <typename Point1, typename Point2>
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struct default_strategy<point_tag, Point1, Point2, spherical_equatorial_tag, spherical_equatorial_tag>
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{
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typedef strategy::distance::haversine<Point1, Point2> type;
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};
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// Note: spherical polar coordinate system requires "get_as_radian_equatorial"
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} // namespace services
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#endif // DOXYGEN_NO_STRATEGY_SPECIALIZATIONS
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}} // namespace strategy::distance
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}} // namespace boost::geometry
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#endif // BOOST_GEOMETRY_STRATEGIES_SPHERICAL_DISTANCE_HAVERSINE_HPP
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