[Octave-cvsupdate] SF.net SVN: octave:[10230] trunk/octave-forge/main/geometry/inst

[<jpi...@us...>]

Revision: 10230
          http://octave.svn.sourceforge.net/octave/?rev=10230&view=rev
Author:   jpicarbajal
Date:     2012-04-15 15:22:55 +0000 (Sun, 15 Apr 2012)
Log Message:
-----------
geometry: Ramer-Douglas-Peucker algorithm to simplify polylines and polygons.

Modified Paths:
--------------
    trunk/octave-forge/main/geometry/inst/polygons2d/simplifypolygon.m
    trunk/octave-forge/main/geometry/inst/polygons2d/simplifypolyline.m
    trunk/octave-forge/main/geometry/inst/shape2d/curve2polyline.m

Modified: trunk/octave-forge/main/geometry/inst/polygons2d/simplifypolygon.m
===================================================================
--- trunk/octave-forge/main/geometry/inst/polygons2d/simplifypolygon.m	2012-04-15 15:18:34 UTC (rev 10229)
+++ trunk/octave-forge/main/geometry/inst/polygons2d/simplifypolygon.m	2012-04-15 15:22:55 UTC (rev 10230)
@@ -15,37 +15,32 @@
 
 %% -*- texinfo -*-
 %% @deftypefn {Function File} {@var{spoly} = } simplifypolygon (@var{poly})
-%% Filter colinear vertex from a 2D polygon.
+%% Simplify a polygon using the Ramer-Douglas-Peucker algorithm.
 %%
 %% @var{poly} is a N-by-2 matrix, each row representing a vertex.
 %%
-%% @seealso{shape2polygon}
+%% @seealso{simplifypolyline, shape2polygon}
 %% @end deftypefn
 
-function polygonsimp = simplifypolygon (polygon)
+function polygonsimp = simplifypolygon (polygon, varargin)
 
-  # Filter colinear points
-  edges = diff(polygon([1:end 1],:));
-  ned = size(edges,1);
-  nxt = [2:ned 1];
+  polygonsimp = simplifypolyline (polygon,varargin{:});
 
-  # check if consecutive edges are parallel
-  para = edges(:,1).*edges(nxt,2) - edges(:,2).*edges(nxt,1);
-  ind = abs(para) > sqrt(eps);
+  # Remove parrallel consecutive edges
+  PL = polygonsimp(1:end-1,:);
+  PC = polygonsimp(2:end,:);
+  PR = polygonsimp([3:end 1],:);
+  a = PL - PC;
+  b = PR - PC;
+  tf = find(isParallel(a,b))+1;
+  polygonsimp (tf,:) = [];
 
-  polygonsimp = polygon(circshift (ind,1),:);
-
-  if isempty(polygonsimp)
-    warning('simplifypolygon:devel',"The simplification gives an empty polygon. Returning original\n");
-    polygonsimp = polygon;
-  end
-
 endfunction
 
 %!test
 %!  P = [0 0; 1 0; 0 1];
 %!  P2 = [0 0; 0.1 0; 0.2 0; 0.25 0; 1 0; 0 1; 0 0.7; 0 0.6; 0 0.3; 0 0.1];
-%! assert(P,simplifypolygon (P2))
+%! assert(simplifypolygon (P2),P,min(P2(:))*eps)
 
 %!demo
 %!

Modified: trunk/octave-forge/main/geometry/inst/polygons2d/simplifypolyline.m
===================================================================
--- trunk/octave-forge/main/geometry/inst/polygons2d/simplifypolyline.m	2012-04-15 15:18:34 UTC (rev 10229)
+++ trunk/octave-forge/main/geometry/inst/polygons2d/simplifypolyline.m	2012-04-15 15:22:55 UTC (rev 10230)
@@ -48,7 +48,8 @@
   parser = inputParser ();
   parser.FunctionName = "simplifypolyline";
   parser = addParamValue (parser,'Nmax', 100, @(x)x>0);
-  parser = addParamValue (parser,'Tol', 1e-4, @(x)x>0);
+  toldef = 1e-4;%max(sumsq(diff(pline_o),2))*2;
+  parser = addParamValue (parser,'Tol', toldef, @(x)x>0);
   parser = addParamValue (parser,'MaxIter', 100, @(x)x>0);
   parser = parse(parser,varargin{:});
 
@@ -56,7 +57,7 @@
   tol       = parser.Results.Tol;
   MaxIter   = parser.Results.MaxIter;
 
-  clear parser
+  clear parser toldef
   msg = ["Maximum number of points reached with maximal error %g." ...
        " Increase '%s' if the result is not satisfactory."];
   # ------ #
@@ -108,8 +109,6 @@
 
 function [dist ii] = dd (p,e,idx)
   [d pos] = distancePointEdge(p,e);
-  tf = abs(pos) <= abs(pos*eps) | abs(pos-1) <= abs((pos-1)*eps);
-  d(tf) = -1;
   [dist ii] = max(d);
   ii = idx(ii);
 endfunction
@@ -137,3 +136,20 @@
 %!
 %! % ---------------------------------------------------------
 %! % Four approximations of the initial polyline with decreasing tolerances.
+
+%!demo
+%! P       = [0 0; 3 1; 3 4; 1 3; 2 2; 1 1];
+%! func    = @(x,y) linspace(x,y,5);
+%! P2(:,1) = cell2mat( ...
+%!             arrayfun (func, P(1:end-1,1),P(2:end,1), ...
+%!             'uniformoutput',false))'(:);
+%! P2(:,2) = cell2mat( ...
+%!             arrayfun (func, P(1:end-1,2),P(2:end,2), ...
+%!             'uniformoutput',false))'(:);
+%!
+%! P2s = simplifypolyline (P2);
+%!
+%! plot(P(:,1),P(:,2),'s',P2(:,1),P2(:,2),'o',P2s(:,1),P2s(:,2),'-ok');
+%!
+%! % ---------------------------------------------------------
+%! % Simplification of a polyline in the plane.

Modified: trunk/octave-forge/main/geometry/inst/shape2d/curve2polyline.m
===================================================================
--- trunk/octave-forge/main/geometry/inst/shape2d/curve2polyline.m	2012-04-15 15:18:34 UTC (rev 10229)
+++ trunk/octave-forge/main/geometry/inst/shape2d/curve2polyline.m	2012-04-15 15:22:55 UTC (rev 10230)
@@ -100,6 +100,7 @@
 %% -- abs(p0-pt) + abs(pt-p1) - abs(p0-p1) almost zero.
 %% -- Curve's tange at 0,t,1 are almost parallel.
 %% -- pt is in chord p0 -> p1.
+%% Do this in isParallel.m and remove this function
 
   PL = p(1:2:end-2,:);
   PC = p(2:2:end-1,:);

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