{"action":"created","issue":{"url":"https://api.github.com/repos/kujason/avod/issues/21","repository_url":"https://api.github.com/repos/kujason/avod","labels_url":"https://api.github.com/repos/kujason/avod/issues/21/labels{/name}","comments_url":"https://api.github.com/repos/kujason/avod/issues/21/comments","events_url":"https://api.github.com/repos/kujason/avod/issues/21/events","html_url":"https://github.com/kujason/avod/issues/21","id":308318337,"number":21,"title":"question regarding 2D IoU in BEV","user":{"login":"johleh","id":16760555,"avatar_url":"https://avatars3.githubusercontent.com/u/16760555?v=4","gravatar_id":"","url":"https://api.github.com/users/johleh","html_url":"https://github.com/johleh","followers_url":"https://api.github.com/users/johleh/followers","following_url":"https://api.github.com/users/johleh/following{/other_user}","gists_url":"https://api.github.com/users/johleh/gists{/gist_id}","starred_url":"https://api.github.com/users/johleh/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/johleh/subscriptions","organizations_url":"https://api.github.com/users/johleh/orgs","repos_url":"https://api.github.com/users/johleh/repos","events_url":"https://api.github.com/users/johleh/events{/privacy}","received_events_url":"https://api.github.com/users/johleh/received_events","type":"User","site_admin":false},"labels":[{"id":851837387,"url":"https://api.github.com/repos/kujason/avod/labels/question","name":"question","color":"d876e3","default":true}],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":4,"created_at":"2018-03-25T03:14:36Z","updated_at":"2018-03-26T19:37:31Z","closed_at":null,"author_association":"NONE","body":"Hello,\r\n\r\nThank you for releasing the code to your paper!\r\n\r\n\"Background anchors are determined by calculating the 2D IoU in BEV between the anchors\r\nand the ground truth bounding boxes. For the car class, anchors with IoU less than 0.3 are considered background anchors, while ones with IoU greater than 0.5\"\r\n\r\nI am trying to figure out how you overcame the problem of IoU calculation for non-axis aligned rectangles to determine negative and positive anchor predictions. The calculation uses 2 box_list objects.\r\nCould you please point me towards the box_list generation for the ground truth labels. Or help me to understand the process with a few words about the content of these box_lists. \r\nIs it an IoU-calculation between axis aligned bounding boxes around the ground truth box and anchor prediction boxes ?\r\n\r\nRegards,\r\nJohannes "},"comment":{"url":"https://api.github.com/repos/kujason/avod/issues/comments/376286044","html_url":"https://github.com/kujason/avod/issues/21#issuecomment-376286044","issue_url":"https://api.github.com/repos/kujason/avod/issues/21","id":376286044,"user":{"login":"johleh","id":16760555,"avatar_url":"https://avatars3.githubusercontent.com/u/16760555?v=4","gravatar_id":"","url":"https://api.github.com/users/johleh","html_url":"https://github.com/johleh","followers_url":"https://api.github.com/users/johleh/followers","following_url":"https://api.github.com/users/johleh/following{/other_user}","gists_url":"https://api.github.com/users/johleh/gists{/gist_id}","starred_url":"https://api.github.com/users/johleh/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/johleh/subscriptions","organizations_url":"https://api.github.com/users/johleh/orgs","repos_url":"https://api.github.com/users/johleh/repos","events_url":"https://api.github.com/users/johleh/events{/privacy}","received_events_url":"https://api.github.com/users/johleh/received_events","type":"User","site_admin":false},"created_at":"2018-03-26T19:37:31Z","updated_at":"2018-03-26T19:37:31Z","author_association":"NONE","body":"I am sorry, i did not write clearly on what my question focused. I didn't mean to ask about the 2 stage approach, i just described the model to check if i understand correctly. \r\n\r\nMost papers concerning the KITTI 3D Benchmark mention IoU thresholds as hard negative mining criterion, but do no explicitly state how to compute it. I think nobody uses exact IoU values for thousands of anchors, because it is too costly to calculate the exact IoU of non-axis aligned rectangles with something like Polygons and clipping algorithm, \r\n\r\nHow you came up with the solution to rotate all boxes to either 0°,180° or 90°,270° is what i was meant to ask, is it just the way it is done for someone with experience in computer vision ?  You use this alignment step i think. Which should work well for most ground truth labels in KITTI, but in general could be not optimal for objects that occur with diagonal orientation (45°,135°..) right ?\r\n"}}
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