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  25 <div class="section">
  26 <div class="titlepage"><div><div><h5 class="title">
  27 <a name="geometry.reference.algorithms.simplify.simplify_3"></a><a class="link" href="simplify_3.html" title="simplify">simplify</a>
  28 </h5></div></div></div>
  29 <p>
  30             <a class="indexterm" name="idp104322320"></a>
  31 Simplify a geometry.
  32           </p>
  33 <h6>
  34 <a name="geometry.reference.algorithms.simplify.simplify_3.h0"></a>
  35             <span class="phrase"><a name="geometry.reference.algorithms.simplify.simplify_3.synopsis"></a></span><a class="link" href="simplify_3.html#geometry.reference.algorithms.simplify.simplify_3.synopsis">Synopsis</a>
  36           </h6>
  37 <p>
  38 </p>
  39 <pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">Geometry</span><span class="special">,</span> <span class="keyword">typename</span> <span class="identifier">Distance</span><span class="special">&gt;</span>
  40 <span class="keyword">void</span> <span class="identifier">simplify</span><span class="special">(</span><span class="identifier">Geometry</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">geometry</span><span class="special">,</span> <span class="identifier">Geometry</span> <span class="special">&amp;</span> <span class="identifier">out</span><span class="special">,</span> <span class="identifier">Distance</span> <span class="keyword">const</span> <span class="special">&amp;</span> <span class="identifier">max_distance</span><span class="special">)</span></pre>
  41 <p>
  42           </p>
  43 <h6>
  44 <a name="geometry.reference.algorithms.simplify.simplify_3.h1"></a>
  45             <span class="phrase"><a name="geometry.reference.algorithms.simplify.simplify_3.parameters"></a></span><a class="link" href="simplify_3.html#geometry.reference.algorithms.simplify.simplify_3.parameters">Parameters</a>
  46           </h6>
  47 <div class="informaltable"><table class="table">
  48 <colgroup>
  49 <col>
  50 <col>
  51 <col>
  52 <col>
  53 </colgroup>
  54 <thead><tr>
  55 <th>
  56                     <p>
  57                       Type
  58                     </p>
  59                   </th>
  60 <th>
  61                     <p>
  62                       Concept
  63                     </p>
  64                   </th>
  65 <th>
  66                     <p>
  67                       Name
  68                     </p>
  69                   </th>
  70 <th>
  71                     <p>
  72                       Description
  73                     </p>
  74                   </th>
  75 </tr></thead>
  76 <tbody>
  77 <tr>
  78 <td>
  79                     <p>
  80                       Geometry const &amp;
  81                     </p>
  82                   </td>
  83 <td>
  84                     <p>
  85                       Any type fulfilling a Geometry Concept
  86                     </p>
  87                   </td>
  88 <td>
  89                     <p>
  90                       geometry
  91                     </p>
  92                   </td>
  93 <td>
  94                     <p>
  95                       input geometry, to be simplified
  96                     </p>
  97                   </td>
  98 </tr>
  99 <tr>
 100 <td>
 101                     <p>
 102                       Geometry &amp;
 103                     </p>
 104                   </td>
 105 <td>
 106                     <p>
 107                       Any type fulfilling a Geometry Concept
 108                     </p>
 109                   </td>
 110 <td>
 111                     <p>
 112                       out
 113                     </p>
 114                   </td>
 115 <td>
 116                     <p>
 117                       output geometry, simplified version of the input geometry
 118                     </p>
 119                   </td>
 120 </tr>
 121 <tr>
 122 <td>
 123                     <p>
 124                       Distance const &amp;
 125                     </p>
 126                   </td>
 127 <td>
 128                     <p>
 129                       numerical type (int, double, ttmath, ...)
 130                     </p>
 131                   </td>
 132 <td>
 133                     <p>
 134                       max_distance
 135                     </p>
 136                   </td>
 137 <td>
 138                     <p>
 139                       distance (in units of input coordinates) of a vertex to other
 140                       segments to be removed
 141                     </p>
 142                   </td>
 143 </tr>
 144 </tbody>
 145 </table></div>
 146 <h6>
 147 <a name="geometry.reference.algorithms.simplify.simplify_3.h2"></a>
 148             <span class="phrase"><a name="geometry.reference.algorithms.simplify.simplify_3.header"></a></span><a class="link" href="simplify_3.html#geometry.reference.algorithms.simplify.simplify_3.header">Header</a>
 149           </h6>
 150 <p>
 151             Either
 152           </p>
 153 <p>
 154             <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
 155           </p>
 156 <p>
 157             Or
 158           </p>
 159 <p>
 160             <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">algorithms</span><span class="special">/</span><span class="identifier">simplify</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
 161           </p>
 162 <h6>
 163 <a name="geometry.reference.algorithms.simplify.simplify_3.h3"></a>
 164             <span class="phrase"><a name="geometry.reference.algorithms.simplify.simplify_3.conformance"></a></span><a class="link" href="simplify_3.html#geometry.reference.algorithms.simplify.simplify_3.conformance">Conformance</a>
 165           </h6>
 166 <p>
 167             The function simplify is not defined by OGC.
 168           </p>
 169 <div class="note"><table border="0" summary="Note">
 170 <tr>
 171 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../../../doc/src/images/note.png"></td>
 172 <th align="left">Note</th>
 173 </tr>
 174 <tr><td align="left" valign="top"><p>
 175               PostGIS contains an algorithm with the same name and the same functionality.
 176               See the <a href="http://www.postgis.org/docs/ST_Simplify.html" target="_top">PostGIS
 177               documentation</a>.
 178             </p></td></tr>
 179 </table></div>
 180 <div class="note"><table border="0" summary="Note">
 181 <tr>
 182 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../../../doc/src/images/note.png"></td>
 183 <th align="left">Note</th>
 184 </tr>
 185 <tr><td align="left" valign="top"><p>
 186               SQL Server contains an algorithm Reduce() with the same functionality.
 187               See the <a href="http://msdn.microsoft.com/en-us/library/bb933814.aspx" target="_top">MSDN
 188               documentation</a>.
 189             </p></td></tr>
 190 </table></div>
 191 <h6>
 192 <a name="geometry.reference.algorithms.simplify.simplify_3.h4"></a>
 193             <span class="phrase"><a name="geometry.reference.algorithms.simplify.simplify_3.behavior"></a></span><a class="link" href="simplify_3.html#geometry.reference.algorithms.simplify.simplify_3.behavior">Behavior</a>
 194           </h6>
 195 <p>
 196             Simplification is done using <a href="http://en.wikipedia.org/wiki/Ramer%E2%80%93Douglas%E2%80%93Peucker_algorithm" target="_top">Douglas-Peucker</a>
 197             (if the default strategy is used).
 198           </p>
 199 <div class="note"><table border="0" summary="Note">
 200 <tr>
 201 <td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../../../doc/src/images/note.png"></td>
 202 <th align="left">Note</th>
 203 </tr>
 204 <tr><td align="left" valign="top"><p>
 205               Geometries might become invalid by using simplify. The simplification
 206               process might create self-intersections.
 207             </p></td></tr>
 208 </table></div>
 209 <h6>
 210 <a name="geometry.reference.algorithms.simplify.simplify_3.h5"></a>
 211             <span class="phrase"><a name="geometry.reference.algorithms.simplify.simplify_3.examples"></a></span><a class="link" href="simplify_3.html#geometry.reference.algorithms.simplify.simplify_3.examples">Examples</a>
 212           </h6>
 213 <p>
 214             Example showing how to simplify a linestring
 215           </p>
 216 <p>
 217 </p>
 218 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>
 219
 220 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 221 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">linestring</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 222 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">point_xy</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 223
 224 <a class="co" name="geometry.reference.algorithms.simplify.simplify_3.c0" href="simplify_3.html#geometry.reference.algorithms.simplify.simplify_3.c1"><img src="../../../../../../../../doc/src/images/callouts/1.png" alt="1" border="0"></a>
 225 <span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">assign</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 226
 227 <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">assign</span><span class="special">;</span>
 228
 229
 230 <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
 231 <span class="special">{</span>
 232     <span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">d2</span><span class="special">::</span><span class="identifier">point_xy</span><span class="special">&lt;</span><span class="keyword">double</span><span class="special">&gt;</span> <span class="identifier">xy</span><span class="special">;</span>
 233
 234     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">linestring</span><span class="special">&lt;</span><span class="identifier">xy</span><span class="special">&gt;</span> <span class="identifier">line</span><span class="special">;</span>
 235     <span class="identifier">line</span> <span class="special">+=</span> <span class="identifier">xy</span><span class="special">(</span><span class="number">1.1</span><span class="special">,</span> <span class="number">1.1</span><span class="special">),</span> <span class="identifier">xy</span><span class="special">(</span><span class="number">2.5</span><span class="special">,</span> <span class="number">2.1</span><span class="special">),</span> <span class="identifier">xy</span><span class="special">(</span><span class="number">3.1</span><span class="special">,</span> <span class="number">3.1</span><span class="special">),</span> <span class="identifier">xy</span><span class="special">(</span><span class="number">4.9</span><span class="special">,</span> <span class="number">1.1</span><span class="special">),</span> <span class="identifier">xy</span><span class="special">(</span><span class="number">3.1</span><span class="special">,</span> <span class="number">1.9</span><span class="special">);</span> <a class="co" name="geometry.reference.algorithms.simplify.simplify_3.c2" href="simplify_3.html#geometry.reference.algorithms.simplify.simplify_3.c3"><img src="../../../../../../../../doc/src/images/callouts/2.png" alt="2" border="0"></a>
 236
 237     <span class="comment">// Simplify it, using distance of 0.5 units</span>
 238     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">linestring</span><span class="special">&lt;</span><span class="identifier">xy</span><span class="special">&gt;</span> <span class="identifier">simplified</span><span class="special">;</span>
 239     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">simplify</span><span class="special">(</span><span class="identifier">line</span><span class="special">,</span> <span class="identifier">simplified</span><span class="special">,</span> <span class="number">0.5</span><span class="special">);</span>
 240     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span>
 241         <span class="special">&lt;&lt;</span> <span class="string">"  original: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">dsv</span><span class="special">(</span><span class="identifier">line</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span>
 242         <span class="special">&lt;&lt;</span> <span class="string">"simplified: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">dsv</span><span class="special">(</span><span class="identifier">simplified</span><span class="special">)</span> <span class="special">&lt;&lt;</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
 243
 244
 245     <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
 246 <span class="special">}</span>
 247 </pre>
 248 <p>
 249           </p>
 250 <div class="calloutlist"><table border="0" summary="Callout list">
 251 <tr>
 252 <td width="5%" valign="top" align="left"><p><a name="geometry.reference.algorithms.simplify.simplify_3.c1"></a><a href="#geometry.reference.algorithms.simplify.simplify_3.c0"><img src="../../../../../../../../doc/src/images/callouts/1.png" alt="1" border="0"></a> </p></td>
 253 <td valign="top" align="left"><p>
 254                 For this example we use Boost.Assign to add points
 255               </p></td>
 256 </tr>
 257 <tr>
 258 <td width="5%" valign="top" align="left"><p><a name="geometry.reference.algorithms.simplify.simplify_3.c3"></a><a href="#geometry.reference.algorithms.simplify.simplify_3.c2"><img src="../../../../../../../../doc/src/images/callouts/2.png" alt="2" border="0"></a> </p></td>
 259 <td valign="top" align="left"><p>
 260                 With Boost.Assign
 261               </p></td>
 262 </tr>
 263 </table></div>
 264 <p>
 265             Output:
 266           </p>
 267 <pre class="programlisting">original: ((1.1, 1.1), (2.5, 2.1), (3.1, 3.1), (4.9, 1.1), (3.1, 1.9))
 268 simplified: ((1.1, 1.1), (3.1, 3.1), (4.9, 1.1), (3.1, 1.9))
 269 </pre>
 270 <h6>
 271 <a name="geometry.reference.algorithms.simplify.simplify_3.h6"></a>
 272             <span class="phrase"><a name="geometry.reference.algorithms.simplify.simplify_3.image_s_"></a></span><a class="link" href="simplify_3.html#geometry.reference.algorithms.simplify.simplify_3.image_s_">Image(s)</a>
 273           </h6>
 274 <p>
 275             <span class="inlinemediaobject"><img src="../../../../svg_simplify_country.png" alt="svg_simplify_country"></span>
 276           </p>
 277 </div>
 278 <table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
 279 <td align="left"></td>
 280 <td align="right"><div class="copyright-footer">Copyright &#169; 2009-2017 Barend
 281       Gehrels, Bruno Lalande, Mateusz Loskot, Adam Wulkiewicz, Oracle and/or its
 282       affiliates<p>
 283         Distributed under the Boost Software License, Version 1.0. (See accompanying
 284         file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
 285       </p>
 286 </div></td>
 287 </tr></table>
 288 <hr>
 289 <div class="spirit-nav">
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