/// <summary> /// Computes a union operation on /// the given geometry, with the supplied precision model. /// <para/> /// The input must be a valid geometry. /// Collections must be homogeneous. /// <para/> /// To union an overlapping set of polygons in a more performant way use <see cref="UnaryUnionNG"/>. /// To union a polygonal coverage or linear network in a more performant way, /// use <see cref="CoverageUnion"/>. /// </summary> /// <param name="geom">The geometry</param> /// <param name="pm">The precision model to use</param> /// <returns>The result of the union operation</returns> /// <seealso cref="OverlayMixedPoints"/> internal static Geometry Union(Geometry geom, PrecisionModel pm) { var ov = new OverlayNG(geom, null, pm, SpatialFunction.Union); var geomOv = ov.GetResult(); return(geomOv); }
/// <summary> /// Reduces the precision of a geometry by rounding and snapping it to the /// supplied <see cref="PrecisionModel"/>.<br/> /// The input geometry must be polygonal or linear. /// <para/> /// The output is always a valid geometry. This implies that input components /// may be merged if they are closer than the grid precision. /// if merging is not desired, then the individual geometry components /// should be processed separately. /// <para/> /// The output is fully noded (i.e. coincident lines are merged and noded). /// This provides an effective way to node / snap-round a collection of <see cref="LineString"/>s. /// </summary> /// <param name="geom">The geometry to reduce</param> /// <param name="pm">The precision model to use</param> /// <returns>The precision-reduced geometry</returns> public static Geometry ReducePrecision(Geometry geom, PrecisionModel pm) { if (geom == null) { throw new ArgumentNullException(nameof(geom)); } var ov = new OverlayNG(geom, null, pm, SpatialFunction.Union); /* * Ensure reducing a area only produces polygonal result. * (I.e. collapse lines are not output) */ if (geom.Dimension == Dimension.Surface) { ov.AreaResultOnly = true; } try { var reduced = ov.GetResult(); return(reduced); } catch (TopologyException ex) { throw new ArgumentException("Reduction failed, possible invalid input", ex); } }
/// <summary> /// Computes an overlay operation for /// the given geometry operands, with the /// noding strategy determined by the precision model. /// </summary> /// <param name="geom0">The first geometry argument</param> /// <param name="geom1">The second geometry argument</param> /// <param name="opCode">The code for the desired overlay operation</param> /// <param name="pm">The precision model to use</param> /// <returns>The result of the overlay operation</returns> public static Geometry Overlay(Geometry geom0, Geometry geom1, SpatialFunction opCode, PrecisionModel pm) { var ov = new OverlayNG(geom0, geom1, pm, opCode); var geomOv = ov.GetResult(); return(geomOv); }
/// <summary> /// Computes a union of a single geometry using a custom noder. /// <para/> /// The primary use of this is to support coverage union. /// Because of this the overlay is performed using strict mode. /// </summary> /// <param name="geom">The geometry to union</param> /// <param name="pm">The precision model to use (maybe be <c>null</c>)</param> /// <param name="noder">The noder to use</param> /// <returns>the result geometry</returns> /// <seealso cref="CoverageUnion"/> internal static Geometry Union(Geometry geom, PrecisionModel pm, INoder noder) { var ov = new OverlayNG(geom, null, pm, SpatialFunction.Union); ov.Noder = noder; ov.StrictMode = true; var geomOv = ov.GetResult(); return(geomOv); }
/// <summary> /// Computes an overlay operation on the given geometry operands, /// using a supplied <see cref="INoder"/>. /// </summary> /// <param name="geom0">The first geometry argument</param> /// <param name="geom1">The second geometry argument</param> /// <param name="opCode">The code for the desired overlay operation</param> /// <param name="noder">The noder to use</param> /// <returns>The result of the overlay operation</returns> public static Geometry Overlay(Geometry geom0, Geometry geom1, SpatialFunction opCode, INoder noder) { var ov = new OverlayNG(geom0, geom1, null, opCode); ov.Noder = noder; var geomOv = ov.GetResult(); return(geomOv); }
/// <summary> /// Self-snaps a geometry by running a union operation with it as the only input. /// This helps to remove narrow spike/gore artifacts to simplify the geometry, /// which improves robustness. /// Collapsed artifacts are removed from the result to allow using /// it in further overlay operations. /// </summary> /// <param name="geom">Geometry to self-snap</param> /// <param name="snapTol">Snap tolerance</param> /// <returns>The snapped geometry (homogenous)</returns> private static Geometry SnapSelf(Geometry geom, double snapTol) { var ov = new OverlayNG(geom, null); var snapNoder = new SnappingNoder(snapTol); ov.Noder = snapNoder; /* * Ensure the result is not mixed-dimension, * since it will be used in further overlay computation. * It may however be lower dimension, if it collapses completely due to snapping. */ ov.StrictMode = true; return(ov.GetResult()); }
/// <summary> /// Computes an overlay operation on /// the given geometry operands, /// using the precision model of the geometry. /// and an appropriate noder. /// <para/> /// The noder is chosen according to the precision model specified. /// <list type="bullet"> /// <item><description>For <see cref="PrecisionModels.Fixed"/> /// a snap-rounding noder is used, and the computation is robust.</description></item> /// <item><description>For <see cref="PrecisionModels.Floating"/> /// a non-snapping noder is used, /// and this computation may not be robust. /// If errors occur a <see cref="TopologyException"/> is thrown.</description></item> /// </list> /// </summary> /// <param name="geom0">The first geometry argument</param> /// <param name="geom1">The second geometry argument</param> /// <param name="opCode">The code for the desired overlay operation</param> /// <returns>The result of the overlay operation</returns> public static Geometry Overlay(Geometry geom0, Geometry geom1, SpatialFunction opCode) { var ov = new OverlayNG(geom0, geom1, opCode); return(ov.GetResult()); }