boost-geometry

问题 The following query seems to be working just fine under MySQL 5.6 (returns 0 for the Area), but on MySQL 5.7 it returns an error saying ERROR 3037 (22023): Invalid GIS data provided to function st_area. . SELECT ST_Area(GeomFromText('POLYGON((0 0, 0 0, 0 0, 0 0, 0 0))')) Is it possible to either ignore the error and return zero, or create a query to filter any such geometries from the query before running it? A very simple schema and query example would be: CREATE TABLE `polygons` (`id` int,

问题 I'm using boost::geometry::union_ to merge a vector of random polygons, and here what I wrote: #include <iostream> #include <vector> #include <fstream> #include <boost/geometry.hpp> #include <boost/geometry/geometries/point_xy.hpp> #include <boost/geometry/geometries/polygon.hpp> #include <boost/geometry/io/wkt/wkt.hpp> #include <boost/foreach.hpp> typedef boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > polygon; void union_polys(std::vector<polygon> In_polys,std

问题 I'm using boost::geometry::union_ to merge a vector of random polygons, and here what I wrote: #include <iostream> #include <vector> #include <fstream> #include <boost/geometry.hpp> #include <boost/geometry/geometries/point_xy.hpp> #include <boost/geometry/geometries/polygon.hpp> #include <boost/geometry/io/wkt/wkt.hpp> #include <boost/foreach.hpp> typedef boost::geometry::model::polygon<boost::geometry::model::d2::point_xy<double> > polygon; void union_polys(std::vector<polygon> In_polys,std

问题 I'm using boost 1.56 on OS X, installed through homebrew. I'm running into a compilation problem - specifically, it appears that I cannot remove values from a boost::geometry::index::rtree. Here's the code I've come up with so far: #include <iostream> #include <vector> #include <string> #include <boost/geometry.hpp> #include <boost/geometry/geometries/point.hpp> #include <boost/geometry/geometries/box.hpp> #include <boost/geometry/index/rtree.hpp> namespace bg = boost::geometry; namespace bgm

问题 How line can be represented using Boost Geometry? I don't need finite segment, but I need infinite lines (maybe Segment or Linestring can be extended?) As I understand I can use boost::geometry::intersects , but I don't know how to define infinite line. 回答1: If you want to test whether an infinite line A intersects a line segment B , this can be done using boost::geometry::strategy::side::side_by_triangle: template <typename Point> struct line { boost::geometry::model::segment<Point> segment;

问题 I'd like to inherit from bg::model::point to extend it with own functionality. The *point*s shall be stored in an rtree. The following minimal example fails to compile the usage of my derived point (boost 1.54, gcc 4.7.2): #include <boost/geometry.hpp> #include <boost/geometry/geometries/point.hpp> #include <boost/geometry/geometries/box.hpp> #include <boost/geometry/index/rtree.hpp> #include <iostream> #include <boost/shared_ptr.hpp> namespace bg = boost::geometry; namespace bgi = boost:

问题 I have a simple DLL doing some calculations with Boost Geometry polygons. (Mostly intersections and differences.) Since the DLL will be most likely called from C# code, and from Delphi and who knows from where else, I should convert the result into arrays that everything can handle. UPDATE: I had simplified and somewhat corrected my code. The new code looks completely different, uses a completely different approach ( for_each_point ), and somehow still doesn't compile. My new code: #include

问题 I want to get perpendicular distance from a point (t) to a line segment (p, q) . The perpendicular may not intersect the line [p, q] . In that case I want to extend the line (p, q) hypothetically and then draw the perpendicular to get the distance. p, q, t are all gps coordinates. I am using boost geometry. typedef boost::geometry::model::point< double, 2, boost::geometry::cs::spherical_equatorial<boost::geometry::degree> > geo_point; typedef boost::geometry::model::segment<geo_point> geo

问题 We have a matrix of given integers (any from 1 to INT_MAX) like 1 2 3 1 3 3 1 3 3 100 2 1 We want to create polygons with same colors for each unique int in matrix so our polygons would have coords/groupings like shown here. and we could generate image like this: Which *(because of vectirisation that was performed would scale to such size like): (sorry for crappy drawings) Is it possible and how to do such thing with boost geometry? Update: So @sehe sad: I'd simply let Boost Geometry do most

问题 I am using the Rtree implementation of boost::geometry to store (lots of) 2D points. Now I need to do distance-based nearest neigbors queries. However, the manual only describes queries as rectangular boxes (i.e. "Get me all the points that are inside this rectangle") or "KNN" queries ("Get me the nearest 'n' points from here). What I want is actually "Get me the set of points that are at a distance less than 'n'". I noticed that you can define a unary-predicate, but is is... unary (thus, not