{"action":"opened","issue":{"url":"https://api.github.com/repos/mshabunin/test2/issues/972","labels_url":"https://api.github.com/repos/mshabunin/test2/issues/972/labels{/name}","comments_url":"https://api.github.com/repos/mshabunin/test2/issues/972/comments","events_url":"https://api.github.com/repos/mshabunin/test2/issues/972/events","html_url":"https://github.com/mshabunin/test2/issues/972","id":96101221,"number":972,"title":"SURF feautures doesn't work with DenseGrid when grid sampling is pair","user":{"login":"opencv-pushbot","id":2051563,"avatar_url":"https://avatars.githubusercontent.com/u/2051563?v=3","gravatar_id":"","url":"https://api.github.com/users/opencv-pushbot","html_url":"https://github.com/opencv-pushbot","followers_url":"https://api.github.com/users/opencv-pushbot/followers","following_url":"https://api.github.com/users/opencv-pushbot/following{/other_user}","gists_url":"https://api.github.com/users/opencv-pushbot/gists{/gist_id}","starred_url":"https://api.github.com/users/opencv-pushbot/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/opencv-pushbot/subscriptions","organizations_url":"https://api.github.com/users/opencv-pushbot/orgs","repos_url":"https://api.github.com/users/opencv-pushbot/repos","events_url":"https://api.github.com/users/opencv-pushbot/events{/privacy}","received_events_url":"https://api.github.com/users/opencv-pushbot/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/mshabunin/test2/labels/auto-transferred","name":"auto-transferred","color":"ededed"},{"url":"https://api.github.com/repos/mshabunin/test2/labels/bug","name":"bug","color":"fc2929"},{"url":"https://api.github.com/repos/mshabunin/test2/labels/category:%20nonfree","name":"category: nonfree","color":"ededed"},{"url":"https://api.github.com/repos/mshabunin/test2/labels/priority:%20normal","name":"priority: normal","color":"ededed"}],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2015-07-20T16:20:28Z","updated_at":"2015-07-20T16:20:28Z","closed_at":null,"body":"Transferred from http://code.opencv.org/issues/2031\r\n```\n|| Alexandre Benoit on 2012-06-08 11:29\n|| Priority: Normal\n|| Affected: None\n|| Category: nonfree\n|| Tracker: Bug\n|| Difficulty: None\n|| PR: None\n|| Platform: None / None\n```\n\nSURF feautures doesn't work with DenseGrid when grid sampling is pair\n-----------\n```\nHi everyone,\r\nI observe that on the current svn trunk and OpenCV2.4 release, the SURF descriptor returns only zeros when used with a Dense grid configured with a pair pixel sampling.\r\nThe problem seems to not appear when using SIFT\r\n\r\nCode samples are below\n```\n\nHistory\n-------\n##### Alexandre Benoit on 2012-06-08 11:45\n```\nHi again, oops, my explanation was a bit wrong at the end, sorry for that, here are the good code samples :\n\nI observe that on the current svn trunk and OpenCV2.4 release, the SURF descriptor returns only zeros when used with a Dense grid configured with a pair pixel sampling.\nThe problem seems to not appear when using SIFT\n\nTypically when the dense grid is such like this :\n<pre>\ncv::Ptr<cv::FeatureDetector> _featureDetector = new cv::DenseFeatureDetector(1.f, 1, 2.5f, 6);)// descritor returns zeros when sampling is 6,8,10,12, however, it \"works\" with sampling like 5,7,9, etc.\n</pre>\n\nand the descriptor being like this :\n<pre>\n_descExtractor = cv::DescriptorExtractor::create(\"SURF\" ); or \"OppenentSURF\"\n</pre>\n\nThen, running the descriptor like this :\n<pre>\n_featureDetector->detect(colorImage, imageKeypoints, mask);\n_descExtractor->compute( colorImage, imageKeypoints, currentImageDescriptors);\n</pre>\n==> here currentImageDescriptors is the right length but it contains only zeros is dense features sampling is a mutiple of 2\n```\n##### Kirill Kornyakov on 2012-06-15 06:47\n```\nAlexandre, thank you for report, but please use wiki \"syntax\":http://code.opencv.org/help/wiki_syntax.html, and do not use High priority by default. All bugs are triaged, and the team will decide about the priority and Target version.\n-   Target version deleted (3.0)\n-   Priority changed from High to Normal\n-   Description changed from Hi everyone, I observe that on the current\n    svn trunk and OpenCV2.4 release, t... to Hi everyone, I observe that\n    on the current svn trunk and OpenCV2.4 release, t... More\n-   Category changed from features2d to nonfree\n```"}}