simplifyPolygon

SIMPLIFYPOLYGON  Douglas-Peucker simplification of a polygon.

   POLY2 = simplifyPolygon(POLY, TOL)
   Simplifies the input polygon using the Douglas-Peucker algorithm. 

   Example
     elli = [20 30 40 20 30];
     poly = ellipseToPolygon(elli, 500);
     poly2 = simplifyPolygon(poly, 1); % use a tolerance equal to 1.
     figure; hold on;
     drawEllipse(elli);
     drawPoint(poly2, 'mo');

   See also
   polygons2d, smoothPolygon, simplifyPolyline, resamplePolygon

   References
   http://en.wikipedia.org/wiki/Ramer-Douglas-Peucker_algorithm

0001 function [poly, keepInds] = simplifyPolygon(poly, varargin)
0002 %SIMPLIFYPOLYGON  Douglas-Peucker simplification of a polygon.
0003 %
0004 %   POLY2 = simplifyPolygon(POLY, TOL)
0005 %   Simplifies the input polygon using the Douglas-Peucker algorithm.
0006 %
0007 %   Example
0008 %     elli = [20 30 40 20 30];
0009 %     poly = ellipseToPolygon(elli, 500);
0010 %     poly2 = simplifyPolygon(poly, 1); % use a tolerance equal to 1.
0011 %     figure; hold on;
0012 %     drawEllipse(elli);
0013 %     drawPoint(poly2, 'mo');
0014 %
0015 %   See also
0016 %   polygons2d, smoothPolygon, simplifyPolyline, resamplePolygon
0017 %
0018 %   References
0019 %   http://en.wikipedia.org/wiki/Ramer-Douglas-Peucker_algorithm
0020 %
0021 
0022 % ------
0023 % Author: David Legland
0024 % e-mail: david.legland@inra.fr
0025 % Created: 2013-03-14,    using Matlab 7.9.0.529 (R2009b)
0026 % Copyright 2013 INRA - Cepia Software Platform.
0027 
0028 % call the simplifyPolyline function by ensuring the last vertex is present
0029 poly = poly([1:end 1], :);
0030 [poly, keepInds] = simplifyPolyline(poly, varargin{:});
0031 
0032 % remove last vertex
0033 poly(end, :) = [];
0034 keepInds(end) = [];