{"id":160,"date":"2017-11-14T13:23:38","date_gmt":"2017-11-14T05:23:38","guid":{"rendered":"http:\/\/119.29.206.68\/?p=160"},"modified":"2019-02-22T22:32:38","modified_gmt":"2019-02-22T14:32:38","slug":"%e9%81%93%e6%a0%bc%e6%8b%89%e6%96%af-%e6%99%ae%e5%85%8b%e6%8a%98%e7%ba%bf%e5%8e%8b%e7%bc%a9%e6%8a%bd%e7%a8%80%e7%ae%97%e6%b3%95-%e5%ae%9e%e7%8e%b0","status":"publish","type":"post","link":"http:\/\/www.whudj.cn\/?p=160","title":{"rendered":"\u9053\u683c\u62c9\u65af-\u666e\u514b\u6298\u7ebf\u538b\u7f29\/\u62bd\u7a00\u7b97\u6cd5 \u5b9e\u73b0"},"content":{"rendered":"<p>\u9053\u683c\u62c9\u65af-\u666e\u514b\u7b97\u6cd5\uff0c\u6839\u636ewiki\uff0c\u5168\u540d<a href=\"https:\/\/en.wikipedia.org\/wiki\/Ramer%E2%80%93Douglas%E2%80%93Peucker_algorithm\">&#8220;Ramer\u2013Douglas\u2013Peucker algorithm&#8221;<\/a>\u00a0\u00a0 \u662f\u4e00\u79cd\u91c7\u7528\u8fed\u4ee3\u5f0f\u65b9\u6cd5\u5bf9\u6298\u7ebf\u8fdb\u884c\u538b\u7f29\u7684\u65b9\u6cd5\uff0c\u9009\u53d6\u4e00\u4e9b\u7279\u5f81\u70b9\u4ee3\u8868\u539f\u6298\u7ebf\uff0c\u5e76\u4e14\u4fdd\u8bc1\u539f\u6298\u7ebf\u7684\u70b9\u8ddd\u79bb\u538b\u7f29\u540e\u7684\u6298\u7ebf\u4e0d\u8d85\u8fc7\u4e00\u5b9a\u7684\u8303\u56f4\u9608\u503c\\(d\\)\u3002<!--more--><\/p>\n<p>\u5373\u5df2\u77e5\u6298\u7ebf\\(l_{old}= (X_1,X_2,&#8230;,X_n)\\),\u6c42\u7d22\u5f15\u5e8f\u5217\\(\\{1,?,&#8230;,?,n\\}\\),\u4f7f\u5f97\u539f\u70b9\u96c6\u5230\u538b\u7f29\u540e\u7684\u65b0\u6298\u7ebf\\(l_{new}=(X_1,X_?,&#8230;,X_?,X_n)\\)\u7684\u8ddd\u79bb\u5c0f\u4e8e\\(d\\)\u3002\u7b97\u6cd5\u601d\u8def\u662f\uff1a<\/p>\n<p>1\uff09\u521d\u59cb\u8fde\u63a5\\(X_1X_n\\),\u8ba1\u7b97\\(X_2,&#8230;,X_{n-1}\\)\u5230\\(X_1X_n\\)\u7684\u8ddd\u79bb\uff0c\u5e76\u5c06\u6700\u5927\u8ddd\u79bb\u503c\\(d_i\\)\u4e0e\\(d\\)\u6bd4\u8f83\uff0c\u5e76\u4e14\u8bb0\u5f55\u6700\u5927\u8ddd\u79bb\u5bf9\u5e94\u7684\u8282\u70b9\\(X_i\\)\u3002\u5982\u679c\\(d_i&lt;d\\);\u7b97\u6cd5\u7ec8\u6b62\u3002<\/p>\n<p>2\uff09\u5982\u679c\\(d_i&gt;=d\\),\u5219\u5c06\\(X_1X_n\\)\u5206\u4e3a\\(X_1X_i\\)\u4e0e\\(X_iX_n\\)\u4e24\u90e8\u5206\uff0c\u5bf9\u4e8e\u6bcf\u4e00\u90e8\u5206\uff0c\u5206\u522b\u6267\u884c\u6b65\u9aa41,\u6ce8\u610f\u6b64\u65f6\u6b65\u9aa4\u4e00\u5bf9\u5e94\u7684\u8d77\u7ec8\u70b9\u5e94\u8be5\u5206\u522b\u4e3a\\( [1,i] ,[i,n] \\)\u3002<\/p>\n<p>3\uff09\u6240\u6709\u5206\u652f\u5168\u90e8\u7ec8\u6b62\u4e4b\u540e\uff0c\u8bb0\u5f55\u5230\u7684\\(\\{(X_i)\\} \\)\u5e8f\u5217\u5c31\u662f\u6240\u6c42\u7684\u8282\u70b9\u5e8f\u5217\u3002<\/p>\n<p>\u63d2\u4e00\u526fwiki\u4e0a\u9762\u7684\u56fe\u7247\uff0c\u76f4\u89c2\u7684\u8bb0\u5f55\u4e86\u7b97\u6cd5\u5904\u7406\u6d41\u7a0b\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"alignnone size-full wp-image-167\" src=\"http:\/\/119.29.206.68\/wp-content\/uploads\/2017\/11\/Douglas-Peucker_animated.gif\" alt=\"\" width=\"220\" height=\"70\" \/><\/p>\n<p>\u6211\u5b9e\u73b0\u7684C++\u7248\u672c\u7684\u9053\u683c\u62c9\u65af-\u666e\u514b\u7b97\u6cd5\u5982\u4e0b<\/p>\n<pre class=\"lang:default decode:true prettyprint  \">\/\/\u70b9\uff0c\u5411\u91cf\u5171\u7528\u7ed3\u6784\r\nstruct point\r\n{\r\n\tdouble x;\r\n\tdouble y;\r\n\tdouble z;\r\n\t\r\n\t\/\/\u5411\u91cf\u70b9\u4e58\r\n\tdouble operator* (const point&amp;);\r\n\tpoint operator-(const point&amp;);\r\n\tpoint operator*(double);\r\n\tpoint(double,double,double);\r\n\t\/\/\u6b63\u5219\u5316\uff0c\u5c06vector \u53d8\u4e3a\u5355\u4f4d\u5411\u91cf\u3002\r\n\tvoid nomorlize();\r\n\t\/\/\u5411\u91cf\u957f\u5ea6\r\n\tdouble length();\r\n};\r\n\r\ntypedef point vector3d;\r\n\r\ndouble point_to_line_distance(const point&amp; p,const point&amp; p0,const point&amp; p1)\r\n{\r\n\t\/\/\u5411\u91cf p1-p0\r\n\tvector3d v(p1.x-p0.x,p1.y-p0.y,p1.z-p0.z);\r\n\t\/\/\u5411\u91cf p\t-p0\r\n\tvector3d v1(p.x-p0.x ,p.y-p0.y ,p.z - p0.z);\r\n\tv.nomorlize();\r\n\r\n\treturn (v1 - v*(v1*v)).length();\r\n}\r\n\r\nvoid _douglas_peucker_compress(const std::vector&lt;point&gt;&amp; vecPoints,double d, int start,int end ,std::vector&lt;int&gt;&amp; indexs)\r\n{\r\n\t\/\/\u53c2\u5165\u53c2\u6570\u5224\u65ad\r\n\tif(start&gt;=end)\r\n\t\treturn ;\r\n\r\n\t\/\/\u9996\u672b\u70b9\r\n\tconst point&amp; start_point = vecPoints[start];\r\n\tconst point&amp; end_point = vecPoints[end];\r\n\t\r\n\tdouble d_max = -1; \/\/\u8bb0\u5f55 (start,end)\u4e2d\u70b9\u5230\u76f4\u7ebf\u7684\u6700\u5927\u8ddd\u79bb\r\n\tint max_index =-1; \/\/\u8ddd\u79bb \u6700\u5927\u8ddd\u79bb\u5bf9\u5e94\u7684\u70b9\u5e8f\u53f7\r\n\r\n\tfor(int i=start+1;i&lt;end;i++)\r\n\t{\r\n\t\tdouble distance = point_to_line_distance(vecPoints[i],start_point,end_point);\r\n\t\tif(distance&gt;d_max)\r\n\t\t{\r\n\t\t\td_max = distance;\r\n\t\t\tmax_index =i;\r\n\t\t}\r\n\t}\r\n\t\r\n\tif(d_max&gt;d)\r\n\t{\r\n\t\t\/\/\u6ce8\u610f\uff0c\u56e0\u4e3a\u8282\u70b9\u7684\u987a\u5e8f\u95ee\u9898\uff0c\u8fd9\u4e24\u4e2a\u51fd\u6570\u7684\u8c03\u7528\u987a\u5e8f\u4e0d\u80fd\u5199\u53cd\uff01\r\n\t\t\/\/\u5728\u505a\u5e76\u884c\u5316\u7684\u65f6\u5019\u4e5f\u9700\u8981\u6ce8\u610f\r\n\t\t_douglas_peucker_compress(vecPoints,d,start,max_index,indexs);\r\n\t\t_douglas_peucker_compress(vecPoints,d,max_index,end,indexs);\r\n\t}else\r\n\t{\r\n\t\t\/\/\u5c06end\u52a0\u5165indexs;\r\n\t\tindexs.push_back(end);\r\n\t}\r\n\r\n}\r\n\r\nvoid douglas_peucker_compress(const std::vector&lt;point&gt;&amp; vecPoints,double d,std::vector&lt;int&gt;&amp; indexs)\r\n{\r\n\tindexs.clear();\r\n\tindexs.push_back(0); \/\/\u52a0\u5165\u9996\u70b9\r\n\t\/\/\u8c03\u7528\u9012\u5f52\u7b97\u6cd5\u6df1\u5ea6\u4f18\u5148\u65b9\u5f0f\u52a0\u5165\u7d22\u5f15\u70b9\r\n\t_douglas_peucker_compress(vecPoints,d,0,vecPoints.size()-1,indexs);\r\n}<\/pre>\n<p>\u5176\u4e2d\uff0c\u5411\u91cf\u7684 \u91cd\u8f7d\u8fd0\u7b97\u7b26\uff0c\u6a21\u957f\uff0c\u5355\u4f4d\u5411\u91cf\u5316\u7b97\u6cd5\u7565\u53bb\u5b9e\u73b0\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u9053\u683c\u62c9\u65af-\u666e\u514b\u7b97\u6cd5\uff0c\u6839\u636ewiki\uff0c\u5168\u540d&#8220;Ramer\u2013Douglas\u2013 &hellip; <a href=\"http:\/\/www.whudj.cn\/?p=160\">Continue reading <span class=\"meta-nav\">&rarr;<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[15],"tags":[16],"_links":{"self":[{"href":"http:\/\/www.whudj.cn\/index.php?rest_route=\/wp\/v2\/posts\/160"}],"collection":[{"href":"http:\/\/www.whudj.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/www.whudj.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/www.whudj.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/www.whudj.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=160"}],"version-history":[{"count":18,"href":"http:\/\/www.whudj.cn\/index.php?rest_route=\/wp\/v2\/posts\/160\/revisions"}],"predecessor-version":[{"id":1243,"href":"http:\/\/www.whudj.cn\/index.php?rest_route=\/wp\/v2\/posts\/160\/revisions\/1243"}],"wp:attachment":[{"href":"http:\/\/www.whudj.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=160"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/www.whudj.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=160"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/www.whudj.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=160"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}