data structures - Finding specific shapes in point clouds quickly -

-

i've got point cloud, , detect occurrences of patterns of points in code.

let's have 1000 points in 3d space, , want detect instances of 3 points form 'l' shape each segment of l has specific length. point cloud may not have exact matches, may close (i.e. in point cloud, length of segment of 'l' may longer/shorter ideal)

my initial idea this:

  1. record distance between points in shape trying detect
  2. create empty 'potential shape'
  3. for each point in our potential shape, examine points at/near distances found in part 1)
  4. if find point, add our potential shape, , repeat part 3) until have points. check angles between points verify shape indeed correct. if not correct, go on next point , start again

the problem approach has terrible worst case running time. ideally, have kind of data structure speed queries 'find points between distancemin , distancemax away given point. can point me useful data structures might help.

i thinking of putting points in octree speed access time.

any other advice on how improve running time? heuristics speed things up?

note: shapes i'm trying find variable. not 'l'. tried looking @ hough transforms, seem useful detecting specific predetermined shapes lines/circles.

in pcl library there's sample consensus module, quoting directly docs:

holds sample consensus (sac) methods ransac , models planes , cylinders. these can combined freely in order detect specific models , paramters in point clouds.

maybe create shapes combining primitives , search them in cloud?.


Comments

Post a Comment

Popular posts from this blog

c# - How to set Z index when using WPF DrawingContext? -

-
how set z-index drawing object when using drawingcontext.drawxxx() methods? the object drawn last have higher z index. can't change index of drawn objects. way draw in order. if using wpf (as placed tag), can use, example, canvas control. create shapes need like polyline obj = new polyline(); //... // ... set properties of obj and add them canvas uielementcollection: yourcanvasname.children.add(obj); //or yourcanvasname.children.insert(i, obj); first items of collection have higher z index. advantages in way: no need redraw on window changes, can anytime move objects , change order.
Read more

razor - Is this a bug in WebMatrix PageData? -

-
i think may have found bug in webmatrix's pagedata, not sure. concerns how pass data partial page calling page. in webmatrix documentation (tutorials, e.g. " 3 - creating consistent look ", , example code), pagedata recommended mechanism pass data between pages (e.g. content page layout page, or partial page). however have found not work other way, pass data partial page calling page. modifying or adding entries in pagedata in partial page, not seem calling page. cutting right down simplest possible example, in test page may have this: @{ pagedata["test"] = "initial entry"; } <p>before calling partial page, test value @pagedata["test"]</p> @renderpage("_testpartial.cshtml") <p>after returning calling page, test value @pagedata["test"]</p> and in _testpartial.cshtml page might have this: @{ pagedata["test"] = "modified entry"; } <p>in partial page...
Read more

android - layout with fragment and framelayout replaced by another fragment and framelayout -

-
edit: so after comments below, revisted , realized hanging me up. imagine client list , client details activity started : public class clientsmainactivity extends fragmentactivity { @override public void oncreate(bundle savedinstancestate) { super.oncreate(savedinstancestate); //studiotabopenhelper db; setcontentview(r.layout.main_client_activity); } } so works great, starts main_client_activity (defined in layout below, , call activity when button on main screen clicked): intent intent = new intent(getactivity(), clientsmainactivity.class); startactivity(intent); easy issue is, clientsmainactivity not call oncreateview or anything, sets layout layout defines fragment, , listfragment. fine cause not trying pass clientsmainactivity , if have hypothetical activity like: sessionmainsactivity called when click on session edit of client, not calling sessionsmainactivity same way (starts activity sets alayout), want layout set defines...
Read more