QuickHull

Short Description

QuickHull library for Icy. Computes convex envelopes of random point sets in 2D or 3D.

Documentation

The QuickHull library for Icy implements 2D and 3D algorithns to calculate convex envelopes from a given (random) set of points.

The 2D version of the algorithm is detailed here (see “alternative method”): https://en.wikipedia.org/wiki/Quickhull

The 3D version of the algorithm is detailed here: https://www.cs.ubc.ca/~lloyd/java/quickhull3d.html

The easiest way to use the library from within Icy is via the Convexify ROI plug-in

The low-level API can be accessed as follows:

• In 2D:

      List points = ...
      // replace the list by its envelope
      points = QuickHull2D.computeConvexEnvelope(points);
      // Conveniently, a region of interest is easy to create
      ROI2DPolygon polygon = new ROI2DPolygon(points);

• In 3D:

     Point3d[] points = ...
     QuickHull3D qhull3d = new QuickHull3D();
     // build the envelope (nothing is returned)
     qhull3d.build(points, points.length);
     // The envelope is built as a mesh (faces and vertices), accessible via:
     Point3d[] hullVertices = qhull3d.getVertices();
     int[][] faces = qhull3d.getVertices();
     // However, conveniently, a ROI can easily be obtained from the QuickHull3D object using
     ROI3DPolygonalMesh mesh = new ROI3DPolygonalMesh(qhull3d);