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dbastondbaston
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Add GEOSGridIntersectionFractions, GEOSSubdivideByGrid
1 parent f7627b4 commit 96f73a4

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‎benchmarks/operation/CMakeLists.txt‎

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@@ -27,4 +27,12 @@ if (benchmark_FOUND)
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$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/benchmarks>)
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target_link_libraries(perf_coverage_union PRIVATE
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benchmark::benchmark geos geos_cxx_flags)
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add_executable(perf_grid_intersection GridIntersectionPerfTest.cpp)
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target_include_directories(perf_grid_intersection PUBLIC
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$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/include>
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$<BUILD_INTERFACE:${PROJECT_BINARY_DIR}/include>
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$<BUILD_INTERFACE:${PROJECT_SOURCE_DIR}/benchmarks>)
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target_link_libraries(perf_grid_intersection
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benchmark::benchmark geos geos_cxx_flags)
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endif()

‎benchmarks/operation/GridIntersectionPerfTest.cpp‎

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/**********************************************************************
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*
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* GEOS - Geometry Engine Open Source
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* http://geos.osgeo.org
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*
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* Copyright (C) 2025 ISciences LLC
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*
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* This is free software; you can redistribute and/or modify it under
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* the terms of the GNU Lesser General Public Licence as published
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* by the Free Software Foundation.
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* See the COPYING file for more information.
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*
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**********************************************************************/
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#include <benchmark/benchmark.h>
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#include <BenchmarkUtils.h>
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#include <geos/geom/Envelope.h>
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#include <geos/geom/prep/PreparedGeometryFactory.h>
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#include <geos/operation/grid/Grid.h>
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#include <geos/operation/grid/GridIntersection.h>
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#include <geos/operation/intersection/Rectangle.h>
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#include <geos/operation/intersection/RectangleIntersection.h>
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using geos::geom::CoordinateXY;
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using geos::geom::Envelope;
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using geos::geom::Geometry;
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using Grid = geos::operation::grid::Grid<geos::operation::grid::bounded_extent>;
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template<bool AreaOnly>
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struct GridIntersection {
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static double Intersection(const Envelope& env, int nx, int ny, const Geometry& g) {
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Grid grid(env, env.getWidth() / nx, env.getHeight() / ny);
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if constexpr (AreaOnly) {
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auto result = geos::operation::grid::GridIntersection::grid_intersection(grid, g);
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float area = 0;
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for (std::size_t i = 0; i < result->rows(); i++) {
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for (std::size_t j = 0; j < result->cols(); j++) {
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area += (*result)(i, j);
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}
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}
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return static_cast<double>(area);
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} else {
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auto subdivided = geos::operation::grid::GridIntersection::subdivide_polygon(grid, g, true);
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return subdivided->getArea();
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}
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}
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};
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using GridIntersectionAreaOnly = GridIntersection<true>;
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using GridIntersectionFull = GridIntersection<false>;
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template<bool UseRectangleIntersection>
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struct SingleIntersection {
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static double Intersection(const Envelope& env, int nx, int ny, const Geometry& g) {
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double dx = env.getWidth() / nx;
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double dy = env.getHeight() / ny;
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double x0 = env.getMinX();
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double y0 = env.getMinY();
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const auto& gfact = *g.getFactory();
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auto prepGeom = geos::geom::prep::PreparedGeometryFactory::prepare(&g);
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double area = 0;
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for (int i = 0; i < nx; i++) {
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for (int j = 0; j < ny; j++) {
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Envelope subEnv(x0 + i*dx, x0 + (i+1)*dx, y0 + j*dy, y0 + (j+1)*dy);
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auto cellGeom = gfact.toGeometry(&subEnv);
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if (!prepGeom->intersects(cellGeom.get())) {
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continue;
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}
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std::unique_ptr<Geometry> isect;
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if constexpr (UseRectangleIntersection) {
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geos::operation::intersection::Rectangle rect(x0 + i*dx, y0 + j*dy, x0 + (i+1)*dx, y0 + (j+1)*dy);
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isect = geos::operation::intersection::RectangleIntersection::clip(g, rect);
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} else {
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isect = g.intersection(cellGeom.get());
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}
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area += isect->getArea();
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}
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}
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return area;
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}
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};
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using PolygonIntersection = SingleIntersection<false>;
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using RectangleIntersection = SingleIntersection<true>;
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template<typename Impl>
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static void BM_GridIntersection(benchmark::State& state)
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{
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auto nCells = state.range(0);
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auto nx = static_cast<int>(std::ceil(std::sqrt(nCells)));
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auto ny = static_cast<int>(std::ceil(std::sqrt(nCells)));
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CoordinateXY center;
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Envelope env(0, nx, 0, ny);
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env.centre(center);
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auto geom = geos::benchmark::createSineStar(center, env.getWidth() / 2, 500);
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for (auto _ : state) {
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Impl::Intersection(env, nx, ny, *geom);
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}
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}
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BENCHMARK_TEMPLATE(BM_GridIntersection, GridIntersectionAreaOnly)->Range(1000, 1000000);
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BENCHMARK_TEMPLATE(BM_GridIntersection, GridIntersectionFull)->Range(1000, 1000000);
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BENCHMARK_TEMPLATE(BM_GridIntersection, RectangleIntersection)->Range(1000, 1000000);
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BENCHMARK_TEMPLATE(BM_GridIntersection, PolygonIntersection)->Range(1000, 1000000);
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BENCHMARK_MAIN();

‎capi/geos_c.cpp‎

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@@ -713,6 +713,19 @@ extern "C" {
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return GEOSClipByRect_r(handle, g, xmin, ymin, xmax, ymax);
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}
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Geometry*
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GEOSSubdivideByGrid(const Geometry* g, double xmin, double ymin, double xmax, double ymax,
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unsigned nx, unsigned ny, int include_exterior)
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{
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return GEOSSubdivideByGrid_r(handle, g, xmin, ymin, xmax, ymax, nx, ny, include_exterior);
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}
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int
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GEOSGridIntersectionFractions(const Geometry* g, double xmin, double ymin, double xmax, double ymax,
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unsigned nx, unsigned ny, float* buf)
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{
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return GEOSGridIntersectionFractions_r(handle, g, xmin, ymin, xmax, ymax, nx, ny, buf);
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}
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Geometry*
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GEOSGeom_transformXY(const GEOSGeometry* g, GEOSTransformXYCallback callback, void* userdata) {

‎capi/geos_c.h.in‎

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@@ -1035,6 +1035,24 @@ extern GEOSGeometry GEOS_DLL *GEOSClipByRect_r(
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double xmin, double ymin,
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double xmax, double ymax);
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/** \see GEOSSubdivideByGrid */
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extern GEOSGeometry GEOS_DLL *GEOSSubdivideByGrid_r(
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GEOSContextHandle_t handle,
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const GEOSGeometry* g,
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double xmin, double ymin,
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double xmax, double ymax,
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unsigned nx, unsigned ny,
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int include_exterior);
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/** \see GEOSGridIntersectionFractions */
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extern int GEOS_DLL GEOSGridIntersectionFractions_r(
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GEOSContextHandle_t handle,
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const GEOSGeometry* g,
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double xmin, double ymin,
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double xmax, double ymax,
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unsigned nx, unsigned ny,
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float* buf);
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/** \see GEOSPolygonize */
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extern GEOSGeometry GEOS_DLL *GEOSPolygonize_r(
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GEOSContextHandle_t handle,
@@ -3788,6 +3806,56 @@ extern GEOSGeometry GEOS_DLL *GEOSClipByRect(
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double xmin, double ymin,
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double xmax, double ymax);
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/**
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* Compute the intersection of a geometry with each polygon in
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* a rectangular grid.
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* \param g The input geometry to be clipped
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* \param xmin Left bound of grd
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* \param ymin Lower bound of grid
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* \param xmax Right bound of grid
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* \param ymax Upper bound of grid
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* \param nx number of columns in grid
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* \param ny number of rows in grid
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* \param include_exterior whether to include portions of the
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input geometry that do not intersect the grid in
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the returned result.
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* \return A geometry collection whose components represent the
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* intersection with each cell in the grid.
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* Caller is responsible for freeing with GEOSGeom_destroy().
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* \see GEOSGetGridIntersectionFractions
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*
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* \since 3.14.0
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*/
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extern GEOSGeometry GEOS_DLL *GEOSSubdivideByGrid(
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const GEOSGeometry* g,
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double xmin, double ymin,
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double xmax, double ymax,
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unsigned nx, unsigned ny,
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int include_exterior);
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/**
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* Determine the fraction of each cell in a rectangular grid
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* that is covered by a polygon.
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* \param g The input geometry
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* \param xmin Left bound of grd
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* \param ymin Lower bound of grid
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* \param xmax Right bound of grid
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* \param ymax Upper bound of grid
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* \param nx number of columns in grid
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* \param ny number of rows in grid
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* \param buf a buffer of size nx*ny to which the grid cell
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* coverage fractions will be written in row-major order
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* \return 1 if the operation was successful, 0 on exception
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*
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* \since 3.14.0
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*/
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extern int GEOS_DLL GEOSGridIntersectionFractions(
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const GEOSGeometry* g,
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double xmin, double ymin,
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double xmax, double ymax,
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unsigned nx, unsigned ny,
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float* buf);
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/**
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* Find paths shared between the two given lineal geometries.
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*

‎capi/geos_ts_c.cpp‎

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@@ -80,6 +80,8 @@
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#include <geos/operation/cluster/GeometryIntersectsClusterFinder.h>
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#include <geos/operation/distance/DistanceOp.h>
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#include <geos/operation/distance/IndexedFacetDistance.h>
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#include <geos/operation/grid/Grid.h>
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#include <geos/operation/grid/GridIntersection.h>
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#include <geos/operation/linemerge/LineMerger.h>
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#include <geos/operation/intersection/Rectangle.h>
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#include <geos/operation/intersection/RectangleIntersection.h>
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});
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}
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Geometry*
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GEOSSubdivideByGrid_r(GEOSContextHandle_t extHandle, const Geometry* g, double xmin, double ymin,
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double xmax, double ymax, unsigned nx, unsigned ny, int include_exterior)
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{
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return execute(extHandle, [&]() {
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Envelope env(xmin, xmax, ymin, ymax);
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double dx = env.getWidth() / static_cast<double>(nx);
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double dy = env.getHeight() / static_cast<double>(ny);
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geos::operation::grid::Grid<geos::operation::grid::bounded_extent> grid(env, dx, dy);
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return geos::operation::grid::GridIntersection::subdivide_polygon(grid, *g, include_exterior).release();
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});
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}
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int
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GEOSGridIntersectionFractions_r(GEOSContextHandle_t extHandle, const Geometry* g, double xmin, double ymin,
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double xmax, double ymax, unsigned nx, unsigned ny, float* buf)
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{
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return execute(extHandle, 0, [&]() {
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Envelope env(xmin, xmax, ymin, ymax);
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double dx = env.getWidth() / static_cast<double>(nx);
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double dy = env.getHeight() / static_cast<double>(ny);
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geos::operation::grid::Grid<geos::operation::grid::bounded_extent> grid(env, dx, dy);
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// Matrix wants a shared_ptr, but we don't actually want anything to be freed because
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// buf is externally owned. So we give it an empty deleter.
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std::shared_ptr<float[]> bufPtr(buf, [](float*) {});
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auto cov = std::make_shared<geos::operation::grid::Matrix<float>>(ny, nx, bufPtr);
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geos::operation::grid::GridIntersection isect(grid, *g, cov);
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1761+
return 1;
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});
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}
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Geometry*
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GEOSGeom_transformXY_r(GEOSContextHandle_t handle, const GEOSGeometry* g, GEOSTransformXYCallback callback, void* userdata) {
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‎include/geos/operation/grid/Cell.h‎

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/**********************************************************************
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*
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* GEOS - Geometry Engine Open Source
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* http://geos.osgeo.org
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*
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* Copyright (C) 2018-2025 ISciences, LLC
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*
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* This is free software; you can redistribute and/or modify it under
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* the terms of the GNU Lesser General Public Licence as published
10+
* by the Free Software Foundation.
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* See the COPYING file for more information.
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*
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**********************************************************************/
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#pragma once
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#include <geos/geom/Envelope.h>
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#include <geos/geom/Geometry.h>
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#include <geos/operation/grid/Side.h>
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#include <geos/operation/grid/Traversal.h>
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namespace geos::operation::grid {
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/**
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* @brief The Cell class stores information about the spatial extent of a `Grid` cell and
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* any cases where a line crosses that cell (recorded in a `Traversal`).
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*/
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class Cell
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{
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public:
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Cell(double xmin, double ymin, double xmax, double ymax)
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: m_box{ xmin, ymin, xmax, ymax }
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{
36+
}
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explicit Cell(const geom::Envelope& b)
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: m_box{ b }
40+
{
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}
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const geom::Envelope& box() const { return m_box; }
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double width() const;
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double height() const;
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double area() const;
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/// Force the last Coordinate processed (via `take`) to be considered as an
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/// exit point, provided that it lies on the boundary of this Cell.
53+
void force_exit();
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/// Returns whether the cell can be determined to be wholly or partially
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/// covered by a polygon.
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bool determined() const;
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/// Return the total length of a linear geometry within this Cell
60+
double traversal_length() const;
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62+
/// Return the fraction of this Cell that is covered by a polygon
63+
double covered_fraction() const;
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65+
/// Return a newly constructed geometry representing the portion of this Cell
66+
/// that is covered by a polygon
67+
std::unique_ptr<geom::Geometry> covered_polygons(const geom::GeometryFactory&) const;
68+
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/// Return the last (most recent) traversal to which a coordinate has been
70+
/// added. The traversal may or may not be completed.
71+
Traversal& last_traversal();
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/**
74+
* Attempt to take a coordinate and add it to a Traversal in progress, or start a new Traversal
75+
*
76+
* @param c Coordinate to process
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* @param prev_original The last *uninterpolated* coordinate preceding `c` in the
78+
* boundary being processed
79+
*
80+
* @return `true` if the Coordinate was inside this cell, `false` otherwise
81+
*/
82+
bool take(const geom::CoordinateXY& c, const geom::CoordinateXY* prev_original = nullptr);
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private:
85+
std::vector<const std::vector<geom::CoordinateXY>*> get_coord_lists() const;
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enum class Location
88+
{
89+
INSIDE,
90+
OUTSIDE,
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BOUNDARY
92+
};
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94+
geom::Envelope m_box;
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std::vector<Traversal> m_traversals;
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Side side(const geom::CoordinateXY& c) const;
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Location location(const geom::CoordinateXY& c) const;
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/// If no Traversals have been started or the most recent Traversal has been completed,
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/// return a new Traversal. Otherwise, return the most recent Traversal.
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Traversal& traversal_in_progress();
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};
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}

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