boostorg
Incorrect result of the function bg::intersection()
This is my code with the define BOOST_GEOMETRY_NO_ROBUSTNESS， It can be compiled by DEV-C + + 5.11,Boost version: 1.72. The answer should be 0, but it's 27. However, if I delete the "#define BOOST_GEOMETRY_NO_ROBUSTNESS", the answer will be correct.
#define BOOST_GEOMETRY_NO_ROBUSTNESS
#include<iostream>
#include <boost/assign.hpp>
#include <boost/assign/list_of.hpp>
#include <boost/geometry/geometry.hpp>
#include <boost/geometry/geometries/point_xy.hpp>
#include <boost/geometry/geometries/polygon.hpp>
using namespace std;
namespace bg = boost::geometry;
int main()
{
typedef bg::model::d2::point_xy<double> DPoint;
typedef bg::model::polygon<DPoint, false> DPolygon;
typedef bg::model::multi_polygon<DPolygon> MPolygon;
DPolygon poly1;
DPolygon poly2;
MPolygon poly;
std::list<DPoint> lstOf = boost::assign::list_of
(DPoint(140.10975222826562, 135.99989776999999))
(DPoint(140.10975222826562, 126.97244753050222))
(DPoint(140.16255693232961, 135.99989776999999))
(DPoint(140.10975222826562, 135.99989776999999));
poly1.outer().assign(lstOf.begin(), lstOf.end());
lstOf = boost::assign::list_of
(DPoint(151.99995129999999, 123.99989777000000))
(DPoint(139.99994018999999, 126.99990054000000))
(DPoint(129.99995129999999, 124.99989777000000))
(DPoint(151.99995129999999, 123.99989777000000));
poly2.outer().assign(lstOf.begin(), lstOf.end());
bg::correct(poly1);
bg::correct(poly2);
bg::intersection(poly1, poly2, poly);
double Area = bg::area(poly);
cout<<Area;
return 1;
}
What compiler and what version of the compiler is this DEV-C + + 5.11 thing?
What compilation flags did you use, especially what optimisations?
I also compiled with MSVC2012 Ver11.0.51106.01. what optimisations? I don't know.
It's quite important to know at least if you do non-optimised debug build or you do optimised build (Release in Visual Studio speak).
DEV-C + + 5.11 : TDM-GCC 4.9.2 32-bit Release. MSVC2012: Release and Debug The answers are all the same. They're all Incorrect. However, if I delete the "#define BOOST_GEOMETRY_NO_ROBUSTNESS", the answer will be correct.
Thanks for checking it's not optimisation related.
if I delete the "#define BOOST_GEOMETRY_NO_ROBUSTNESS", the answer will be correct.
For some/many cases, that is what you should do, because without that macro defined, the algorithms will perform rescaling to integer for more numerically robust solution (default behaviour).
https://github.com/boostorg/geometry/blob/b930d335653063cb6f9c9641956b3cac5f80e86a/include/boost/geometry/core/config.hpp#L25-L29
You may still need to define the macro in order to disable the rescaling for some/edge cases as you discovered in the previous issue you reported #662.
I think this case can be closed.
I have two code. If I add the "#define BOOST_GEOMETRY_NO_ROBUSTNESS", the code1 will be incorrect, the code2 will be correct. but if I delete the "#define BOOST_GEOMETRY_NO_ROBUSTNESS", the code1 will be correct, the code2 will be incorrect. what can I do? thanks.
code1
#define BOOST_GEOMETRY_NO_ROBUSTNESS
#include<iostream>
#include <boost/assign.hpp>
#include <boost/assign/list_of.hpp>
#include <boost/geometry/geometry.hpp>
#include <boost/geometry/geometries/point_xy.hpp>
#include <boost/geometry/geometries/polygon.hpp>
using namespace std;
namespace bg = boost::geometry;
int main()
{
typedef bg::model::d2::point_xy<double> DPoint;
typedef bg::model::polygon<DPoint, false> DPolygon;
typedef bg::model::multi_polygon<DPolygon> MPolygon;
DPolygon poly1;
DPolygon poly2;
MPolygon poly;
std::list<DPoint> lstOf = boost::assign::list_of
(DPoint(140.10975222826562, 135.99989776999999))
(DPoint(140.10975222826562, 126.97244753050222))
(DPoint(140.16255693232961, 135.99989776999999))
(DPoint(140.10975222826562, 135.99989776999999));
poly1.outer().assign(lstOf.begin(), lstOf.end());
lstOf = boost::assign::list_of
(DPoint(151.99995129999999, 123.99989777000000))
(DPoint(139.99994018999999, 126.99990054000000))
(DPoint(129.99995129999999, 124.99989777000000))
(DPoint(151.99995129999999, 123.99989777000000));
poly2.outer().assign(lstOf.begin(), lstOf.end());
bg::correct(poly1);
bg::correct(poly2);
bg::intersection(poly1, poly2, poly);
double Area = bg::area(poly);
cout<<Area;
return 1;
}
code2:
#define BOOST_GEOMETRY_NO_ROBUSTNESS
#include<iostream>
#include <boost/assign.hpp>
#include <boost/assign/list_of.hpp>
#include <boost/geometry/geometry.hpp>
#include <boost/geometry/geometries/point_xy.hpp>
#include <boost/geometry/geometries/polygon.hpp>
using namespace std;
namespace bg = boost::geometry;
int main()
{
typedef bg::model::d2::point_xy<double> DPoint;
typedef bg::model::polygon<DPoint, false> DPolygon;
typedef bg::model::multi_polygon<DPolygon> MPolygon;
DPolygon poly1;
DPolygon poly2;
MPolygon poly;
std::list<DPoint> lstOf = boost::assign::list_of
(DPoint(171.60480351137778, 162.32096650635697))
(DPoint(172.21795926332567, 162.99736073096460))
(DPoint(172.21795926332567, 170.00000000000000))
(DPoint(171.60480351137778, 170.00000000000000))
(DPoint(171.60480351137778, 162.32096650635697));
poly1.outer().assign(lstOf.begin(), lstOf.end());
lstOf = boost::assign::list_of
(DPoint(200.00000000000000, 166.00002000000001))
(DPoint(184.00004999999999, 166.00002000000001))
(DPoint(180.00004999999999, 164.00002000000001))
(DPoint(169.99998889000000, 162.00000277999999))
(DPoint(182.00000000000000, 159.00000000000000))
(DPoint(200.00000000000000, 159.00000000000000))
(DPoint(200.00000000000000, 166.00002000000001));
poly2.outer().assign(lstOf.begin(), lstOf.end());
bg::correct(poly1);
bg::correct(poly2);
bg::intersection(poly1, poly2, poly);
double Area = bg::area(poly);
cout<<Area;
return 1;
}
The first case looks like that:
red - poly1 green - poly2 blue - poly (result)
With BOOST_GEOMETRY_NO_ROBUSTNESS the result is equal to the poly2 (with additional point). Without the result is empty. Even if the result was non-empty the intersection should not be equal to poly2.
[0] {140.10975222826562, 126.97244753050222}
[1] {139.99994018999999, 126.99990054000000}
[2] {129.99995129999999, 124.99989777000000}
[3] {151.99995129999999, 123.99989777000000}
[4] {140.10975222826562, 126.97244753050222}
The CW/CCW point order does not affect the result. Tested with VS2017.
The second case:
As @linshu77 said it's the other way around WRT BOOST_GEOMETRY_NO_ROBUSTNESS. However this time the poly1 is the result.
{171.60480351137778, 162.32096650635697}
{172.21795926332567, 162.99736073096460}
{172.21795926332567, 170.00000000000000}
{171.60480351137778, 170.00000000000000}
{171.60480351137778, 162.32096650635697}