{"action":"created","issue":{"url":"https://api.github.com/repos/mavlink/mavlink/issues/749","repository_url":"https://api.github.com/repos/mavlink/mavlink","labels_url":"https://api.github.com/repos/mavlink/mavlink/issues/749/labels{/name}","comments_url":"https://api.github.com/repos/mavlink/mavlink/issues/749/comments","events_url":"https://api.github.com/repos/mavlink/mavlink/issues/749/events","html_url":"https://github.com/mavlink/mavlink/pull/749","id":241552880,"number":749,"title":"Common: Ability to specify ground altitude for landing waypoints","user":{"login":"AndreasAntener","id":5750020,"avatar_url":"https://avatars0.githubusercontent.com/u/5750020?v=4","gravatar_id":"","url":"https://api.github.com/users/AndreasAntener","html_url":"https://github.com/AndreasAntener","followers_url":"https://api.github.com/users/AndreasAntener/followers","following_url":"https://api.github.com/users/AndreasAntener/following{/other_user}","gists_url":"https://api.github.com/users/AndreasAntener/gists{/gist_id}","starred_url":"https://api.github.com/users/AndreasAntener/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/AndreasAntener/subscriptions","organizations_url":"https://api.github.com/users/AndreasAntener/orgs","repos_url":"https://api.github.com/users/AndreasAntener/repos","events_url":"https://api.github.com/users/AndreasAntener/events{/privacy}","received_events_url":"https://api.github.com/users/AndreasAntener/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":22,"created_at":"2017-07-09T20:08:03Z","updated_at":"2017-08-18T08:39:08Z","closed_at":null,"pull_request":{"url":"https://api.github.com/repos/mavlink/mavlink/pulls/749","html_url":"https://github.com/mavlink/mavlink/pull/749","diff_url":"https://github.com/mavlink/mavlink/pull/749.diff","patch_url":"https://github.com/mavlink/mavlink/pull/749.patch"},"body":"This is an attempt to consolidate approaches on vertical landings. I don't know all the methods used but I believe that this currently solved differently across implementations. Possibly someone already has an elegant solution for this problem, if so, please let me know :).\r\n\r\n**The problem**: With only one altitude field for a landing mission item we have to decide if the vehicle approaches on that altitude (horizontally) until it's above the landing spot **OR** if that altitude marks the height where we should expect ground (can be used in two step vertical landing or as fallback for a failed distance sensor).\r\n\r\nFor fixed-wing vehicles doing a glide slope landing these two altitudes are the same in the final phase which is why I'm focusing only on vertical landings right now.\r\n\r\nMy proposal is to use parameter 3 to specify the ground altitude. That way the actual altitude field is preserved as the target flying altitude and won't change it's meaning depending on the `MAV_CMD`.\r\n\r\nI believe that would be a sensible solution, however it is worth mentioning that there are already other options:\r\n1. Use 2 waypoints: One for the approach and one for the actual landing where the altitude field serves as ground altitude.\r\n2. Use actual terrain data on the flight controller.\r\n\r\n"},"comment":{"url":"https://api.github.com/repos/mavlink/mavlink/issues/comments/323295628","html_url":"https://github.com/mavlink/mavlink/pull/749#issuecomment-323295628","issue_url":"https://api.github.com/repos/mavlink/mavlink/issues/749","id":323295628,"user":{"login":"LorenzMeier","id":1208119,"avatar_url":"https://avatars3.githubusercontent.com/u/1208119?v=4","gravatar_id":"","url":"https://api.github.com/users/LorenzMeier","html_url":"https://github.com/LorenzMeier","followers_url":"https://api.github.com/users/LorenzMeier/followers","following_url":"https://api.github.com/users/LorenzMeier/following{/other_user}","gists_url":"https://api.github.com/users/LorenzMeier/gists{/gist_id}","starred_url":"https://api.github.com/users/LorenzMeier/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/LorenzMeier/subscriptions","organizations_url":"https://api.github.com/users/LorenzMeier/orgs","repos_url":"https://api.github.com/users/LorenzMeier/repos","events_url":"https://api.github.com/users/LorenzMeier/events{/privacy}","received_events_url":"https://api.github.com/users/LorenzMeier/received_events","type":"User","site_admin":false},"created_at":"2017-08-18T08:39:08Z","updated_at":"2017-08-18T08:39:08Z","body":"@AndreasAntener Could you update the PR to match your last comment? Thanks!"}}
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