Create an envelope surrounding a set of points in a two-dimensional space. The shape in the union of a polygon and circles surrounding each point. The polygon is determined using an extension of methods to determine the tangent line to two circles and is the solution to the multiple pulley problem. The points can used to highlight a region in a two-dimensional space.

Package: | PlotRegionHighlighter |

Type: | Package |

Version: | 1.0 |

Date: | 2013-04-04 |

License: | GPL-2 |

The generateEnvelope function is called with a two-column matrix with each row containing the xy coordinates for each point. Along with vector of radii for the circles surrounding each point, the function generates a list of points defining the envelope surrounding the set of points. The envelope is computed as if it were specifying a pulley that passed around the circles with a minimum perimenter and minimum area for a convex shape containing all the circles. The algorithm uses formulas for calculating the set of lines that is tangent to a pair of circles.

Elliot Noma

Maintainer: Elliot Noma <noma@garrettassetmanagement.com>

http://en.wikipedia.org/wiki/Belt_problem

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