The Java Topology Suite (JTS)

The Java Topology Suite (JTS) provides a wealth of geometric functions for 2D geometry, that's useful for computational geometry and application domains such as geographical information systems. A summary of its features can be found here.

One of JTS's tools is TestBuilder for visualizing geometries, but I found it more useful to implement a simple GeomsViewer.java, which is called from my examples. All of the "Screenshot" links included with the examples go to images generated by GeomsViewer.

Note: GeoViewer uses a JPanel as a canvas, so the y-axis runs down the window. This means that a shape with its points ordered clockwise appears to be drawn in a counter-clockwise direction. See Triangles.java for an example of this drawback.

My Examples

BuildGeoms.java creates a variety of geometries, including Point, MultiPoint, LineString, MultiLineString, Polygon, polygons with holes (LinearRing), MultiPolygon, and GeometryCollection. Screenshot.
BuildShapes.java builds shapes from collections of points; moves and rotates a shape using JTS's AffineTransformation class, and tests for similarity using the HausdorffSimilarityMeasure and AreaSimilarityMeasure classes. Screenshot.
WTKExamples.java converts WTK (Well-Known Text) strings into geometries, loads WTK shapes from a file, and writes them out. Screenshot. The input data file is data1.txt.
GeomOps.java illustrates an assortment of geometry methods, including getArea(), getLength(), distance(), nearestPoints(), isWithinDistance(), contains(), within(), coveredBy(), intersects(), intersection(), disjoint(), crosses(), touches(), overlaps(), equals(), and equalsExact(). Screenshot.
ClosestPoints.java computes the distance and closest points between geometries using JTS's DistanceOp. Screenshot.
Triangles.java employs computational geometry methods commonly used with triangles, mostly via JTS's Triangle class. It calculates interior angles, performs acuteness tests, measures lengths, perimeters, areas, and finds the centroid, circumcenter, orthocenter, and incenter. Screenshot.
Overlays.java utilizes the boolean shape operations: union, intersection, difference, and symmetric difference, and also performs shape buffering. Screenshots: here, here.
Polygonize.java uses the Polygonizer class to convert lines into polygons. Screenshot.
LineAdjust.java utilizes the DouglasPeuckerSimplifier class to simplify lines, and Densifier to add points. Screenshot.
Dissolver.java shows how to use the LineDissolver class. Screenshot.
LinesMerge.java sews lines together using LineMerger. Screenshot.
Fixer.java employs GeometryFixer to fix invalid geometries by spliting them into parts or by reorganizing coordinates. Screenshot.
TreeSearch.java can use Quadtree or Kdtree to determine which points lie inside a rectangle. Screenshot.
Covers.java: applies three different point coverings: Delaunay triangulation, Voronoi diagramming, and the convex hull. Screenshots: here, here, and here.
Triangulate.java triangulates a polygon in two ways – using constrained Delaunay processing and polygon triangulation. Screenshot.
Conforming.java triangulates using the ConformingDelaunayTriangulationBuilder class. Screenshot.
Concavity.java calculates concave hulls. Screenshot.
Utils.java: a repository for various utilities.
GeomsViewer.java creates a window that displays JTS geometries as shapes in a JPanel.

The Java Topology Suite (JTS)

My Examples

Other Downloads and Links