{"action":"created","issue":{"url":"https://api.github.com/repos/raulmur/ORB_SLAM2/issues/71","repository_url":"https://api.github.com/repos/raulmur/ORB_SLAM2","labels_url":"https://api.github.com/repos/raulmur/ORB_SLAM2/issues/71/labels{/name}","comments_url":"https://api.github.com/repos/raulmur/ORB_SLAM2/issues/71/comments","events_url":"https://api.github.com/repos/raulmur/ORB_SLAM2/issues/71/events","html_url":"https://github.com/raulmur/ORB_SLAM2/issues/71","id":148920281,"number":71,"title":"Scale Drift Issue","user":{"login":"sunstarchan","id":6760921,"avatar_url":"https://avatars.githubusercontent.com/u/6760921?v=3","gravatar_id":"","url":"https://api.github.com/users/sunstarchan","html_url":"https://github.com/sunstarchan","followers_url":"https://api.github.com/users/sunstarchan/followers","following_url":"https://api.github.com/users/sunstarchan/following{/other_user}","gists_url":"https://api.github.com/users/sunstarchan/gists{/gist_id}","starred_url":"https://api.github.com/users/sunstarchan/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/sunstarchan/subscriptions","organizations_url":"https://api.github.com/users/sunstarchan/orgs","repos_url":"https://api.github.com/users/sunstarchan/repos","events_url":"https://api.github.com/users/sunstarchan/events{/privacy}","received_events_url":"https://api.github.com/users/sunstarchan/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":8,"created_at":"2016-04-17T05:25:22Z","updated_at":"2016-07-07T09:04:22Z","closed_at":null,"body":"@raulmur \r\n\r\nI tested some dataset, and I meet scale drift issue, especially when the car turns along the road. \r\n\r\ndo you know why scale is not consistent during straight road and curve road? \r\nAny feedback is appreciated. \r\n\r\nThanks."},"comment":{"url":"https://api.github.com/repos/raulmur/ORB_SLAM2/issues/comments/231023290","html_url":"https://github.com/raulmur/ORB_SLAM2/issues/71#issuecomment-231023290","issue_url":"https://api.github.com/repos/raulmur/ORB_SLAM2/issues/71","id":231023290,"user":{"login":"ank700","id":13818948,"avatar_url":"https://avatars.githubusercontent.com/u/13818948?v=3","gravatar_id":"","url":"https://api.github.com/users/ank700","html_url":"https://github.com/ank700","followers_url":"https://api.github.com/users/ank700/followers","following_url":"https://api.github.com/users/ank700/following{/other_user}","gists_url":"https://api.github.com/users/ank700/gists{/gist_id}","starred_url":"https://api.github.com/users/ank700/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/ank700/subscriptions","organizations_url":"https://api.github.com/users/ank700/orgs","repos_url":"https://api.github.com/users/ank700/repos","events_url":"https://api.github.com/users/ank700/events{/privacy}","received_events_url":"https://api.github.com/users/ank700/received_events","type":"User","site_admin":false},"created_at":"2016-07-07T09:04:22Z","updated_at":"2016-07-07T09:04:22Z","body":"Hi @joyousrabbit , great explanation. Now it is much clear to me.\r\n\r\nSo basically, the algorithm's internal scale should remain constant from frame to frame, theoretically.\r\nIf I change the way the scale is calculated when we see frame 2 and so on , such that Dis_BC = 80 for frame1 and DIS_BC=70 for frame2(assuming it to be correct) because the 2 viewpoints could be different in orientation also. But, this way the final pose error could be even larger, I think. \r\nWhere is this scale value (for frame 2) calculated in the code? I found invMedianDepth, but this is just for the scaling of pose and map points during initialization.\r\n\r\nIs there any other way to correct the internal scale error internally? Using an IMU is definitely not a good option and because my usage is indoors GPS also makes no sense.\r\n\r\nOR\r\n\r\nIn my case, I am using a height sensor to calculate scale and most of my motion is in a XZ plane, I will have to do some motion in Y axis only, after regular intervals based on keyframes created to update my computed scale value.\r\n\r\nThanks"}}
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