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8fbb9b3655
* Catch up with r75977 changes with new layout of IO formats in geometry/io/<FORMAT>/ * General maintenance in tests and examples. [SVN r75979]
63 lines
2.7 KiB
C++
63 lines
2.7 KiB
C++
// Boost.Geometry (aka GGL, Generic Geometry Library)
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//
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// Copyright (c) 2007-2011 Barend Gehrels, Amsterdam, the Netherlands.
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// Copyright (c) 2008-2011 Bruno Lalande, Paris, France.
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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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//
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// Projection example 1, direct
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#include <boost/geometry/geometry.hpp>
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#include <boost/geometry/geometries/point_xy.hpp>
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#include <boost/geometry/extensions/algorithms/parse.hpp>
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#include <boost/geometry/io/wkt/iomanip.hpp>
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#include <boost/geometry/extensions/gis/latlong/latlong.hpp>
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#include <boost/geometry/extensions/gis/projections/parameters.hpp>
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#include <boost/geometry/extensions/gis/projections/proj/robin.hpp>
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int main()
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{
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using namespace boost::geometry;
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// Initialize projection parameters
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projection::parameters par = projection::init("+ellps=WGS84 +units=m");
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// Construct a Robinson projection, using specified point types
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// (This delivers a projection without virtual methods. Note that in p02 example
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// the projection is created using a factory, which delivers a projection with virtual methods)
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typedef model::ll::point<degree> point_ll_deg;
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typedef model::d2::point_xy<double> point_xy;
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projection::robin_spheroid<point_ll_deg, point_xy> prj(par);
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// Define Amsterdam / Barcelona in decimal degrees / degrees/minutes
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point_ll_deg amsterdam = parse<point_ll_deg>("52.4N", "5.9E");
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point_ll_deg barcelona = parse<point_ll_deg>("41 23'N", "2 11'E");
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point_xy pa, pb;
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// Now do the projection. "Forward" means from latlong to meters.
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// (Note that a map projection might fail. This is not 'exceptional'.
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// Therefore the forward function does not throw but returns false)
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if (prj.forward(amsterdam, pa) && prj.forward(barcelona, pb))
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{
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std::cout << "Amsterdam: " << pa << std::endl << "Barcelona: " << pb << std::endl;
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std::cout << "Distance (unprojected):" << distance(amsterdam, barcelona) / 1000.0 << " km" << std::endl;
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std::cout << "Distance ( projected):" << distance(pa, pb) / 1000.0 << " km" << std::endl;
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// Do the inverse projection. "Inverse" means from meters to latlong
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// It also might fail or might not exist, not all projections
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// have their inverse implemented
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point_ll_deg a1;
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if (prj.inverse(pa, a1))
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{
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std::cout << "Amsterdam (original): " << amsterdam << std::endl
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<< "Amsterdam (projected, and back):" << a1 << std::endl;
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std::cout << "Distance a-a': " << distance(amsterdam, a1) << " meter" << std::endl;
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}
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}
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return 0;
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}
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