{"action":"opened","issue":{"url":"https://api.github.com/repos/tonny-zhang/GraphTool/issues/13","labels_url":"https://api.github.com/repos/tonny-zhang/GraphTool/issues/13/labels{/name}","comments_url":"https://api.github.com/repos/tonny-zhang/GraphTool/issues/13/comments","events_url":"https://api.github.com/repos/tonny-zhang/GraphTool/issues/13/events","html_url":"https://github.com/tonny-zhang/GraphTool/issues/13","id":70033682,"number":13,"title":"geo数据进行抽稀过程","user":{"login":"tonny-zhang","id":1396702,"avatar_url":"https://avatars.githubusercontent.com/u/1396702?v=3","gravatar_id":"","url":"https://api.github.com/users/tonny-zhang","html_url":"https://github.com/tonny-zhang","followers_url":"https://api.github.com/users/tonny-zhang/followers","following_url":"https://api.github.com/users/tonny-zhang/following{/other_user}","gists_url":"https://api.github.com/users/tonny-zhang/gists{/gist_id}","starred_url":"https://api.github.com/users/tonny-zhang/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/tonny-zhang/subscriptions","organizations_url":"https://api.github.com/users/tonny-zhang/orgs","repos_url":"https://api.github.com/users/tonny-zhang/repos","events_url":"https://api.github.com/users/tonny-zhang/events{/privacy}","received_events_url":"https://api.github.com/users/tonny-zhang/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-04-22T06:12:58Z","updated_at":"2015-04-22T06:12:58Z","closed_at":null,"body":"在对原始geo数据进行抽稀时遇到了几个问题：\r\n### 原始简单做法\r\n把每个polygon数据按照一定的距离间隔进行过滤，得到一个大于指定距离间隔的点数据，但这样的做法有一个问题，多个polygon数据进行描边时会出现不重叠现象（画出的结果表现为视觉上认为是一条线的出现不同程序的间隙），这是因为在对每个polygon进行数据过滤的时候在不同面的公共边进行了不同的抽稀过程。\r\n\r\n### 解决办法\r\n要解决上面的问题，现在的处理过程如下：\r\n1. 遍历所有点，对点进行分类（按照点所在面的个数及前后点所在面的情况可以分为：结点、端点）\r\n2. 遍历所有面数据按照端点法对面进行切割成不同的弧段，缓存弧段数据及面弧段的关系列表\r\n3. 对弧段进行抽稀（按不同需求抽稀出不同分辨率的数据）\r\n4. 按面和弧段关系对数据进行还原，得到最后抽稀后的数据"}}