mapnik/test/unit/projection/proj_transform.cpp

#include "catch.hpp"

#include <mapnik/projection.hpp>
#include <mapnik/proj_transform.hpp>
#include <mapnik/geometry/box2d.hpp>
#include <cmath>
#include <tuple>

TEST_CASE("projection transform")
{
    SECTION("Test bounding box transforms - 4326 to 3857")
    {
        mapnik::projection proj_4326("epsg:4326");
        mapnik::projection proj_3857("epsg:3857");

        CHECK(proj_4326.is_geographic());
        CHECK(!proj_3857.is_geographic());

        mapnik::proj_transform prj_trans(proj_4326, proj_3857);

        double minx = -45.0;
        double miny = 55.0;
        double maxx = -40.0;
        double maxy = 75.0;

        mapnik::box2d<double> bbox(minx, miny, maxx, maxy);
        INFO(bbox.to_string());

        CHECKED_IF(prj_trans.forward(bbox))
        {
            CHECK(bbox.minx() == Approx(-5009377.085697311));
            CHECK(bbox.miny() == Approx(7361866.1130511891));
            CHECK(bbox.maxx() == Approx(-4452779.631730943));
            CHECK(bbox.maxy() == Approx(12932243.1119920239));
        }

        CHECKED_IF(prj_trans.backward(bbox))
        {
            CHECK(bbox.minx() == Approx(minx));
            CHECK(bbox.miny() == Approx(miny));
            CHECK(bbox.maxx() == Approx(maxx));
            CHECK(bbox.maxy() == Approx(maxy));
        }
    }

#if defined(MAPNIK_USE_PROJ)
    SECTION("test proj_transform failure behavior")
    {
        mapnik::projection proj_4269("epsg:4269");
        mapnik::projection proj_3857("epsg:3857");
        mapnik::proj_transform prj_trans(proj_4269, proj_3857);
        mapnik::proj_transform prj_trans2(proj_3857, proj_4269);

        // test valid coordinate
        double x0 = -180.0;
        double y0 = -60.0;
        CHECK(prj_trans.forward(&x0, &y0, nullptr, 1, 1));
        CHECK(x0 == Approx(-20037508.3427892439));
        CHECK(y0 == Approx(-8399737.8896366451));
        double x1 = -180.0;
        double y1 = -60.0;
        CHECK(prj_trans2.backward(&x1, &y1, nullptr, 1, 1));
        CHECK(x1 == Approx(-20037508.3427892439));
        CHECK(y1 == Approx(-8399737.8896366451));

        // now test invalid coordinate
        double x2 = -181.0;
        double y2 = -91.0;
        prj_trans.forward(&x2, &y2, nullptr, 1, 1);
        CHECK(std::isinf(x2));
        CHECK(std::isinf(y2));
        double x3 = -181.0;
        double y3 = -91.0;
        prj_trans2.backward(&x3, &y3, nullptr, 1, 1);
        CHECK(std::isinf(x3));
        CHECK(std::isinf(y3));
    }

    SECTION("test forward/backward transformations")
    {
        // WGS 84 - World Geodetic System 1984, used in GPS
        mapnik::projection proj_4236("epsg:4236");
        // OSGB 1936 / British National Grid -- United Kingdom Ordnance Survey
        mapnik::projection proj_27700("epsg:27700");
        // WGS 84 / Equal Earth Greenwich
        mapnik::projection proj_8857("epsg:8857");
        // European Terrestrial Reference System 1989 (ETRS89)
        mapnik::projection proj_4937("epsg:4937");
        //"Webmercator" WGS 84 / Pseudo-Mercator -- Spherical Mercator, Google Maps, OpenStreetMap, Bing, ArcGIS, ESRI
        mapnik::projection proj_3857("epsg:3857");

        mapnik::proj_transform tr1(proj_4236, proj_27700);
        mapnik::proj_transform tr2(proj_4236, proj_8857);
        mapnik::proj_transform tr3(proj_4236, proj_4236);
        mapnik::proj_transform tr4(proj_4236, proj_4937);
        mapnik::proj_transform tr5(proj_4236, proj_3857);
        std::initializer_list<std::reference_wrapper<mapnik::proj_transform>> transforms = {tr1, tr2, tr3, tr4, tr5};

        std::initializer_list<std::tuple<double, double>> coords = {
          {-4.0278869, 57.8796955}, // Dórnach, Highland
          {-4.2488787, 55.8609825}, // Glaschú, Alba
          {-1.4823897, 51.8726941}, // Charlbury, England
          {-3.9732612, 51.7077400}  // Felindre, Cymru
        };

        for (auto const& c : coords)
        {
            double x0, y0;
            std::tie(x0, y0) = c;
            for (mapnik::proj_transform const& tr : transforms)
            {
                double x1 = x0;
                double y1 = y0;
                tr.forward(&x1, &y1, nullptr, 1, 1);
                tr.backward(&x1, &y1, nullptr, 1, 1);
                CHECK(x0 == Approx(x1));
                CHECK(y0 == Approx(y1));
            }
        }
    }

    // Github Issue https://github.com/mapnik/mapnik/issues/2648
    SECTION("Test proj antimeridian bbox")
    {
        mapnik::projection prj_geog("epsg:4326");
        mapnik::projection prj_proj("epsg:2193");

        mapnik::proj_transform prj_trans_fwd(prj_proj, prj_geog);
        mapnik::proj_transform prj_trans_rev(prj_geog, prj_proj);

        // reference values taken from proj4 command line tool:
        // (non-corner points assume PROJ_ENVELOPE_POINTS == 20)
        //
        //  cs2cs -Ef %.10f epsg:2193 +to epsg:4326 <<END
        //        2105800 3087000 # left-most
        //        1495200 3087000 # bottom-most
        //        2105800 7173000 # right-most
        //        3327000 7173000 # top-most
        //  END
        //
        // wrong = mapnik.Box2d(-177.3145325044, -62.3337481525,
        //                       178.0277836332, -24.5845974912)
        const mapnik::box2d<double> better(-180.0, -62.3337481525, 180.0, -24.5845974912);

        {
            mapnik::box2d<double> ext(274000, 3087000, 3327000, 7173000);
            CHECKED_IF(prj_trans_fwd.forward(ext, PROJ_ENVELOPE_POINTS))
            {
                CHECK(ext.minx() == Approx(better.minx()));
                CHECK(ext.miny() == Approx(better.miny()));
                CHECK(ext.maxx() == Approx(better.maxx()));
                CHECK(ext.maxy() == Approx(better.maxy()));
            }
        }

        {
            // check the same logic works for .backward()
            mapnik::box2d<double> ext(274000, 3087000, 3327000, 7173000);
            CHECKED_IF(prj_trans_rev.backward(ext, PROJ_ENVELOPE_POINTS))
            {
                CHECK(ext.minx() == Approx(better.minx()));
                CHECK(ext.miny() == Approx(better.miny()));
                CHECK(ext.maxx() == Approx(better.maxx()));
                CHECK(ext.maxy() == Approx(better.maxy()));
            }
        }

        // reference values taken from proj4 command line tool:
        //
        //  cs2cs -Ef %.10f epsg:2193 +to epsg:4326 <<END
        //        274000 3087000 # left-most
        //        276000 3087000 # bottom-most
        //        276000 7173000 # right-most
        //        274000 7173000 # top-most
        //  END
        //
        const mapnik::box2d<double> normal(148.7639922894, -60.1222810241, 159.9548489296, -24.9771195155);

        {
            // checks for not being snapped (ie. not antimeridian)
            mapnik::box2d<double> ext(274000, 3087000, 276000, 7173000);
            CHECKED_IF(prj_trans_fwd.forward(ext, PROJ_ENVELOPE_POINTS))
            {
                CHECK(ext.minx() == Approx(normal.minx()));
                CHECK(ext.miny() == Approx(normal.miny()));
                CHECK(ext.maxx() == Approx(normal.maxx()));
                CHECK(ext.maxy() == Approx(normal.maxy()));
            }
        }

        {
            // check the same logic works for .backward()
            mapnik::box2d<double> ext(274000, 3087000, 276000, 7173000);
            CHECKED_IF(prj_trans_rev.backward(ext, PROJ_ENVELOPE_POINTS))
            {
                CHECK(ext.minx() == Approx(normal.minx()));
                CHECK(ext.miny() == Approx(normal.miny()));
                CHECK(ext.maxx() == Approx(normal.maxx()));
                CHECK(ext.maxy() == Approx(normal.maxy()));
            }
        }
    }
#endif

    SECTION("proj_transform of coordinate arrays with stride > 1")
    {
        mapnik::projection const proj_4326("epsg:4326");
        mapnik::projection const proj_3857("epsg:3857");
        mapnik::projection const proj_2193("epsg:2193");

        SECTION("lonlat <-> Web Mercator")
        {
            //  cs2cs -Ef %.10f epsg:4326 +to epsg:3857 <<END
            //      170.142139 -43.595056
            //      175.566667 -39.283333
            //  END
            //
            //  170.142139 -43.595056   18940136.2759583741 -5402988.5324898539
            //  175.566667 -39.283333   19543991.9707122259 -4762338.2380718365
            //
            mapnik::geometry::point<double> points[] = {{170.142139, -43.595056}, {175.566667, -39.283333}};
            // this transform is calculated by Mapnik (well_known_srs.cpp)
            mapnik::proj_transform lonlat_to_webmerc(proj_4326, proj_3857);
            CHECKED_IF(lonlat_to_webmerc.forward(&points[0].x, &points[0].y, nullptr, 2, 2))
            {
                CHECK(points[0].x == Approx(18940136.2759583741));
                CHECK(points[0].y == Approx(-5402988.5324898539));
                CHECK(points[1].x == Approx(19543991.9707122259));
                CHECK(points[1].y == Approx(-4762338.2380718365));
            }
            CHECKED_IF(lonlat_to_webmerc.backward(&points[0].x, &points[0].y, nullptr, 2, 2))
            {
                CHECK(points[0].x == Approx(170.142139));
                CHECK(points[0].y == Approx(-43.595056));
                CHECK(points[1].x == Approx(175.566667));
                CHECK(points[1].y == Approx(-39.283333));
            }
        }

#ifdef MAPNIK_USE_PROJ
        SECTION("lonlat <-> New Zealand Transverse Mercator 2000")
        {
            mapnik::projection const proj_2193("epsg:2193");
            //  cs2cs -Ef %.10f epsg:4326 +to epsg:2193 <<END
            //      170.142139 -43.595056
            //      175.566667 -39.283333
            //  END
            //
            //  170.142139 -43.595056   1369316.0970041484  5169132.9750701785
            //  175.566667 -39.283333   1821377.9170061364  5648640.2106032455
            //
            mapnik::geometry::point<double> points[] = {{170.142139, -43.595056}, {175.566667, -39.283333}};
            // this transform is not calculated by Mapnik (needs Proj4)
            mapnik::proj_transform lonlat_to_nztm(proj_4326, proj_2193);
            CHECKED_IF(lonlat_to_nztm.forward(&points[0].x, &points[0].y, nullptr, 2, 2))
            {
                CHECK(points[0].x == Approx(1369316.0970041484));
                CHECK(points[0].y == Approx(5169132.9750701785));
                CHECK(points[1].x == Approx(1821377.9170061364));
                CHECK(points[1].y == Approx(5648640.2106032455));
            }
            CHECKED_IF(lonlat_to_nztm.backward(&points[0].x, &points[0].y, nullptr, 2, 2))
            {
                CHECK(points[0].x == Approx(170.142139));
                CHECK(points[0].y == Approx(-43.595056));
                CHECK(points[1].x == Approx(175.566667));
                CHECK(points[1].y == Approx(-39.283333));
            }
        }
#endif // MAPNIK_USE_PROJ
    }
}