1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>simplify</title> 5<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../../index.html" title="Chapter 1. Geometry"> 8<link rel="up" href="../simplify.html" title="simplify"> 9<link rel="prev" href="simplify_4_with_strategy.html" title="simplify (with strategy)"> 10<link rel="next" href="../sym_difference.html" title="sym_difference"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="simplify_4_with_strategy.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../simplify.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../sym_difference.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 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="idm45635689149744"></a> 31Simplify 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"><</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">></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">&</span> <span class="identifier">geometry</span><span class="special">,</span> <span class="identifier">Geometry</span> <span class="special">&</span> <span class="identifier">out</span><span class="special">,</span> <span class="identifier">Distance</span> <span class="keyword">const</span> <span class="special">&</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 & 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 & 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 & 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"><</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">></span></code> 155 </p> 156<p> 157 Or 158 </p> 159<p> 160 <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special"><</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">></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"><</span><span class="identifier">iostream</span><span class="special">></span> 219 220<span class="preprocessor">#include</span> <span class="special"><</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">></span> 221<span class="preprocessor">#include</span> <span class="special"><</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">></span> 222<span class="preprocessor">#include</span> <span class="special"><</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">></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"><</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">></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"><</span><span class="keyword">double</span><span class="special">></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"><</span><span class="identifier">xy</span><span class="special">></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"><</span><span class="identifier">xy</span><span class="special">></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"><<</span> <span class="string">" original: "</span> <span class="special"><<</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"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span> 242 <span class="special"><<</span> <span class="string">"simplified: "</span> <span class="special"><<</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"><<</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)) 268simplified: ((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 © 2009-2019 Barend Gehrels, Bruno Lalande, Mateusz Loskot, Adam 281 Wulkiewicz, Oracle and/or its affiliates<p> 282 Distributed under the Boost Software License, Version 1.0. (See accompanying 283 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>) 284 </p> 285</div></td> 286</tr></table> 287<hr> 288<div class="spirit-nav"> 289<a accesskey="p" href="simplify_4_with_strategy.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../simplify.html"><img src="../../../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../../../index.html"><img src="../../../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="../sym_difference.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 290</div> 291</body> 292</html> 293
