Package org.locationtech.jts.algorithm
Robustness
Geometrical algorithms involve a combination of combinatorial and numerical computation. As with all numerical computation using finite-precision numbers, the algorithms chosen are susceptible to problems of robustness. A robustness problem occurs when a numerical calculation produces an incorrect answer for some inputs due to round-off errors. Robustness problems are especially serious in geometric computation, since they can result in errors during topology building.There are many approaches to dealing with the problem of robustness in geometrical computation. Not surprisingly, most robust algorithms are substantially more complex and less performant than the non-robust versions. Fortunately, JTS is sensitive to robustness problems in only a few key functions (such as line intersection and the point-in-polygon test). There are efficient robust algorithms available for these functions, and these algorithms are implemented in JTS.
Computational Performance
Runtime performance is an important consideration for a production-quality implementation of geometric algorithms. The most computationally intensive algorithm used in JTS is intersection detection. JTS methods need to determine both all intersection between the line segments in a single Geometry (self-intersection) and all intersections between the line segments of two different Geometries.The obvious naive algorithm for intersection detection (comparing every segment with every other) has unacceptably slow performance. There is a large literature of faster algorithms for intersection detection. Unfortunately, many of them involve substantial code complexity. JTS tries to balance code simplicity with performance gains. It uses some simple techniques to produce substantial performance gains for common types of input data.
Package Specification
- Java Topology Suite Technical Specifications
- OpenGIS Simple Features Specification for SQL
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Interface Summary Interface Description BoundaryNodeRule An interface for rules which determine whether node points which are in boundaries ofLineal
geometry components are in the boundary of the parent geometry collection. -
Class Summary Class Description Angle Utility functions for working with angles.Area Functions for computing area.BoundaryNodeRule.EndPointBoundaryNodeRule ABoundaryNodeRule
which specifies that any points which are endpoints of lineal components are in the boundary of the parent geometry.BoundaryNodeRule.Mod2BoundaryNodeRule ABoundaryNodeRule
specifies that points are in the boundary of a lineal geometry iff the point lies on the boundary of an odd number of components.BoundaryNodeRule.MonoValentEndPointBoundaryNodeRule ABoundaryNodeRule
which determines that only endpoints with valency of exactly 1 are on the boundary.BoundaryNodeRule.MultiValentEndPointBoundaryNodeRule ABoundaryNodeRule
which determines that only endpoints with valency greater than 1 are on the boundary.Centroid Computes the centroid of aGeometry
of any dimension.CGAlgorithms Deprecated. CGAlgorithms3D Basic computational geometry algorithms for geometry and coordinates defined in 3-dimensional Cartesian space.CGAlgorithmsDD Implements basic computational geometry algorithms usingDD
arithmetic.ConvexHull Computes the convex hull of aGeometry
.Distance Functions to compute distance between basic geometric structures.HCoordinate Represents a homogeneous coordinate in a 2-D coordinate space.InteriorPoint Computes an interior point of a
.Geometry
InteriorPointArea Computes a point in the interior of an areal geometry.InteriorPointLine Computes a point in the interior of an linear geometry.InteriorPointPoint Computes a point in the interior of an point geometry.Intersection Functions to compute intersection points between lines and line segments.Length Functions for computing length.LineIntersector ALineIntersector
is an algorithm that can both test whether two line segments intersect and compute the intersection point(s) if they do.MinimumBoundingCircle Computes the Minimum Bounding Circle (MBC) for the points in aGeometry
.MinimumDiameter Computes the minimum diameter of aGeometry
.Orientation Functions to compute the orientation of basic geometric structures including point triplets (triangles) and rings.PointLocation Functions for locating points within basic geometric structures such as lines and rings.PointLocator RayCrossingCounter Counts the number of segments crossed by a horizontal ray extending to the right from a given point, in an incremental fashion.RectangleLineIntersector Computes whether a rectangle intersects line segments.RobustDeterminant Implements an algorithm to compute the sign of a 2x2 determinant for double precision values robustly.RobustLineIntersector A robust version ofLineIntersector
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Exception Summary Exception Description NotRepresentableException Indicates that aHCoordinate
has been computed which is not representable on the Cartesian plane.