{
  "id": 330,
  "title": "Nature of values",
  "url": "/competitions/WIC2011/discussion/330",
  "author_name": "",
  "post_date": "2011-03-11T22:10:18Z",
  "votes": null,
  "comment_count": 2,
  "views": 2883,
  "content": "Is there any information on the nature of the data and methodologies used to create it?<div>eg chaincode8order4_4096[1234] - i (barely) understand chain codes but what exactly do the 8,4,4096,1234 mean?</div><div>Thanks</div><div><span class=\"Apple-tab-span\" style=\"white-space:pre\">\t</span>Jon<br><div><br></div></div>",
  "messages": [
    {
      "id": "1980",
      "postDate": "03/11/2011 22:10:18",
      "content": "Is there any information on the nature of the data and methodologies used to create it?<div>eg chaincode8order4_4096[1234] - i (barely) understand chain codes but what exactly do the 8,4,4096,1234 mean?</div><div>Thanks</div><div><span class=\"Apple-tab-span\" style=\"white-space:pre\">\t</span>Jon<br><div><br></div></div>",
      "rawMarkdown": "",
      "votes": null
    },
    {
      "id": "1981",
      "postDate": "03/11/2011 22:10:18",
      "content": "I have previously used those features for signature verification. I used them here to create the benchmark.<br>A detailed description of these features will hopefully soon be published in a journal paper.<br>I will be happy to co-author an article with participants who have got an interesting way of using these features.<br><br>In the following, I will try to answer your question about chain code.<br>Chain codes are computed from the binary skeleton in our case.<br>For an introduction to chain codes please visit:<br>http://www.cs.ru.nl/~ths/rt2/col/h9/9gebiedENG.html#9.2.1<br><br>The histogram of chain codes gives an idea about the distibution of the 8 main directions.<br><span id=\"post_text_content_1980\">for example, chaincodeHist_8[5]</span> gives you the proportion of 5 in the chain code.<br><br>It is interesting to note that if we do not take the orientation into account, we can consider all values of 4 as<span id=\"post_text_content_1980\"></span> similar to 0, 5 similar to 1, 6 to 2 and 7 to 3.<br>To obtain this, we just compute chain_code%4<br>So chaincodeHist_4[3]<span id=\"post_text_content_1980\"></span> gives you the proportion of 3 in the 4-values chain code.<br><br>Now, if I am interested in the distribution of successive patterns, like \"21\", in my chain code, I will have to shift to (what I call) order 2. In order 2, we have 8*8 possible combinations, that's 64.<br>So <span id=\"post_text_content_1980\">chaincode8order2_64[0] gives you the proportion of </span>\"00\" in your chain code.<br>and <span id=\"post_text_content_1980\">chaincode8order2_64[1] gives you the proportion of </span>\"01\" in your chain code...etc<br><br>I don't know what combination does 1234 correspond to in order 4, but it should be easy to compute.<br>",
      "rawMarkdown": "",
      "votes": null
    },
    {
      "id": "1994",
      "postDate": "03/11/2011 22:10:18",
      "content": "Thanks - that is very helpful.<div><br></div><div>Jon</div>",
      "rawMarkdown": "",
      "votes": null
    }
  ],
  "comments": [
    {
      "id": 1981,
      "author_name": "ahassaine",
      "author_url": "",
      "post_date": "03/11/2011 22:10:18",
      "content": "I have previously used those features for signature verification. I used them here to create the benchmark.<br>A detailed description of these features will hopefully soon be published in a journal paper.<br>I will be happy to co-author an article with participants who have got an interesting way of using these features.<br><br>In the following, I will try to answer your question about chain code.<br>Chain codes are computed from the binary skeleton in our case.<br>For an introduction to chain codes please visit:<br>http://www.cs.ru.nl/~ths/rt2/col/h9/9gebiedENG.html#9.2.1<br><br>The histogram of chain codes gives an idea about the distibution of the 8 main directions.<br><span id=\"post_text_content_1980\">for example, chaincodeHist_8[5]</span> gives you the proportion of 5 in the chain code.<br><br>It is interesting to note that if we do not take the orientation into account, we can consider all values of 4 as<span id=\"post_text_content_1980\"></span> similar to 0, 5 similar to 1, 6 to 2 and 7 to 3.<br>To obtain this, we just compute chain_code%4<br>So chaincodeHist_4[3]<span id=\"post_text_content_1980\"></span> gives you the proportion of 3 in the 4-values chain code.<br><br>Now, if I am interested in the distribution of successive patterns, like \"21\", in my chain code, I will have to shift to (what I call) order 2. In order 2, we have 8*8 possible combinations, that's 64.<br>So <span id=\"post_text_content_1980\">chaincode8order2_64[0] gives you the proportion of </span>\"00\" in your chain code.<br>and <span id=\"post_text_content_1980\">chaincode8order2_64[1] gives you the proportion of </span>\"01\" in your chain code...etc<br><br>I don't know what combination does 1234 correspond to in order 4, but it should be easy to compute.<br>",
      "votes": null,
      "replies": []
    },
    {
      "id": 1994,
      "author_name": "jonred",
      "author_url": "",
      "post_date": "03/11/2011 22:10:18",
      "content": "Thanks - that is very helpful.<div><br></div><div>Jon</div>",
      "votes": null,
      "replies": []
    }
  ],
  "raw_markdown_by_id": {
    "1980": "",
    "1981": "",
    "1994": ""
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  "source": "meta"
}