{"id":7649,"date":"2021-01-15T20:13:52","date_gmt":"2021-01-16T02:13:52","guid":{"rendered":"http:\/\/w0ep.us\/OM\/?p=7649"},"modified":"2021-01-15T20:13:52","modified_gmt":"2021-01-16T02:13:52","slug":"april-tags","status":"publish","type":"post","link":"http:\/\/w0ep.us\/OM\/?p=7649","title":{"rendered":"April Tags"},"content":{"rendered":"\n

[Today’s run: 3.5 mile interval workout on the treadmill]<\/p>\n\n\n\n

I was doing some research recently involving camera system and we needed a way to locate objects in view of the camera. Someone suggested april tags. So I read up on them. And I had a simple sample program running on my computer.<\/p>\n\n\n\n

April Tags<\/a> come from the APRIL Robotics Laboratory at the University of Michigan. They are patterns of black and white squares. A family of patterns will be generated with a limited number of patterns. All of the patterns in that family are unique. And they are directionally unique: they aren’t symmetrical or mirrored.<\/p>\n\n\n\n

The result is that they can be detected in a scene and the detection software can tell their orientation as well as position. Not only will the software know this pattern is #12 (or whatever), it will know the center of that pattern and it will know it’s distance and orientation in relation to the camera. It is pretty cool stuff.<\/p>\n\n\n\n

Here is a video from youtube. <\/a> There are multiple tags in the picture. The software is marking each tag with lines in a “box” which show the pattern number and the orientation of each tag in three dimensions. Those aren’t added to the video with later editing, that is done in real time. <\/p>\n\n\n\n

I printed out some tags and waved them around and it does work.<\/p>\n\n\n\n

We’ve grown used to machine readable tagging systems like barcodes, UPC, square QR codes and many others. April Tags have been designed specifically to indicate position in space.<\/p>\n\n\n\n

In this video<\/a>, the people are driving a remote vehicle which has a big april tag on a piece of cardboard. The flying drone is automatically following the tag at a fixed distance, height and orientation.<\/p>\n","protected":false},"excerpt":{"rendered":"

[Today’s run: 3.5 mile interval workout on the treadmill] I was doing some research recently involving camera system and we needed a way to locate objects in view of the camera. Someone suggested april tags. So I read up on them. And I had a simple sample program running on my computer. April Tags come […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[8],"tags":[],"class_list":["post-7649","post","type-post","status-publish","format-standard","hentry","category-other-thoughts"],"_links":{"self":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/7649","targetHints":{"allow":["GET"]}}],"collection":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=7649"}],"version-history":[{"count":2,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/7649\/revisions"}],"predecessor-version":[{"id":7651,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=\/wp\/v2\/posts\/7649\/revisions\/7651"}],"wp:attachment":[{"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=7649"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=7649"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/w0ep.us\/OM\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=7649"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}