我想将一个multi_polygon中所有相关的多边形连接在一起。如何实现这样的操作?
我们有如下图像(一个绿色的multi_polygon),我们想要进行优化(可以看到黄色虚线 - 是对multi_polygon中每个多边形执行的简化结果,而不是针对整个multi_polygon):
以下是可编译代码,可生成此类图像:
#include <iostream>
#include <fstream>
#include <boost/assign.hpp>
#include <boost/algorithm/string.hpp>
#include <boost/geometry/geometry.hpp>
#include <boost/geometry/geometries/geometries.hpp>
#include <boost/geometry/multi/geometries/multi_polygon.hpp>
#include <boost/geometry/extensions/io/svg/svg_mapper.hpp>
template <typename Geometry1, typename Geometry2>
void create_svg(std::string const& filename, Geometry1 const& a, Geometry2 const& b)
{
typedef typename boost::geometry::point_type<Geometry1>::type point_type;
std::ofstream svg(filename.c_str());
boost::geometry::svg_mapper<point_type> mapper(svg, 400, 400);
mapper.add(a);
mapper.add(b);
mapper.map(a, "fill-opacity:0.5;fill:rgb(153,204,0);stroke:rgb(153,204,0);stroke-width:2");
mapper.map(b, "opacity:0.8;fill:none;stroke:rgb(255,128,0);stroke-width:4;stroke-dasharray:1,7;stroke-linecap:round");
}
boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > make_point(int x, int y)
{
boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > return_item;
boost::geometry::model::d2::point_xy<double> p1(x, y);
boost::geometry::model::d2::point_xy<double> p2(x-1, y);
boost::geometry::model::d2::point_xy<double> p3(x-1, y-1);
boost::geometry::model::d2::point_xy<double> p4(x, y-1);
boost::geometry::append( return_item, p1);
boost::geometry::append( return_item, p2);
boost::geometry::append( return_item, p3);
boost::geometry::append( return_item, p4);
return return_item;
}
int main()
{
// create a container for joined points structure
boost::geometry::model::multi_polygon< boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > > output, simpl;
// join points one by one (because one day we would have many=))
output.push_back(make_point(1,1));
boost::geometry::correct(output);
output.push_back(make_point(2,1));
boost::geometry::correct(output);
output.push_back(make_point(3,1));
boost::geometry::correct(output);
output.push_back(make_point(4,1));
boost::geometry::correct(output);
output.push_back(make_point(5,1));
boost::geometry::correct(output);
output.push_back(make_point(2,2));
boost::geometry::correct(output);
output.push_back(make_point(3,2));
boost::geometry::correct(output);
output.push_back(make_point(5,2));
boost::geometry::correct(output);
output.push_back(make_point(5,5));
boost::geometry::correct(output);
// simplify joined structure
boost::geometry::simplify(output, simpl, 0.5);
// create an svg image
create_svg("make_envelope.svg", output, simpl );
}
需要至少boost 1.47.0和3个文件,这些文件可以从boost/geometry/extensions/io/svg/获取。
我需要的很简单:如何对相关的多边形进行分组?在这种情况下,我们将在我们的多边形中获得2个多边形-如图所示的红色和绿色:
更新:
因此,我在此处找到了关于dissolve的信息,并创建了使用环来创建单元格的示例代码:
#include <iostream>
#include <fstream>
#include <boost/assign.hpp>
//Boost
#include <boost/algorithm/string.hpp>
#include <boost/geometry/geometry.hpp>
#include <boost/geometry/geometries/geometries.hpp>
#include <boost/geometry/multi/geometries/multi_polygon.hpp>
#include <boost/geometry/geometries/adapted/boost_tuple.hpp>
BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS(cs::cartesian)
#include <boost/foreach.hpp>
//Boost Geometry extensions (from trunk)
#include <boost/geometry/extensions/io/svg/svg_mapper.hpp>
template <typename Geometry1, typename Geometry2>
void create_svg(std::string const& filename, Geometry1 const& a, Geometry2 const& b)
{
typedef typename boost::geometry::point_type<Geometry1>::type point_type;
std::ofstream svg(filename.c_str());
boost::geometry::svg_mapper<point_type> mapper(svg, 400, 400);
mapper.add(a);
mapper.add(b);
mapper.map(a, "fill-rule:nonzero;fill-opacity:0.5;fill:rgb(153,204,0);stroke:rgb(153,204,0);stroke-width:2;");
mapper.map(b, "opacity:0.8;fill:none;stroke:rgb(255,128,0);stroke-width:4;stroke-dasharray:1,7;stroke-linecap:round");
}
void make_point(int x, int y, boost::geometry::model::ring<boost::geometry::model::d2::point_xy<double> > & ring)
{
using namespace boost::assign;
ring +=
boost::geometry::model::d2::point_xy<double>(x-1, y-1),
boost::geometry::model::d2::point_xy<double>(x, y-1),
boost::geometry::model::d2::point_xy<double>(x, y),
boost::geometry::model::d2::point_xy<double>(x-1, y),
boost::geometry::model::d2::point_xy<double>(x-1, y-1);
}
int main()
{
using namespace boost::assign;
boost::geometry::model::ring<boost::geometry::model::d2::point_xy<double> > ring0, ring1,ring;
boost::geometry::model::multi_polygon< boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > > outputw;
make_point(1, 1, ring) ;
make_point(2, 1, ring) ;
make_point(3, 1, ring) ;
make_point(4, 1, ring) ;
make_point(5, 1, ring) ;
make_point(2, 2, ring) ;
make_point(3, 2, ring) ;
make_point(5, 2, ring) ;
boost::geometry::model::ring<boost::geometry::model::d2::point_xy<double> > output;
boost::geometry::simplify(ring, output, 1);
// create an svg image
create_svg("make_envelope.svg", ring, output );
}
它返回这样的环图片:
如果我们可以使用dissolve将其转换为多边形,那么就可以解决我的一些问题。但看起来现在由于这个编译器错误问题,我们不能这样做。这个问题的描述可以在这里找到。