Gordon Posted January 18, 2007 Share Posted January 18, 2007 I've had a search but most of the convex hull threads seem to be years old. Is there an in-built way to generate convex hulls from a set of points that I'm missing? Cheers. Quote Link to comment Share on other sites More sharing options...
edward Posted January 18, 2007 Share Posted January 18, 2007 Nope, but I think there's enough workarounds right now. Quote Link to comment Share on other sites More sharing options...
Gordon Posted January 19, 2007 Author Share Posted January 19, 2007 Nope, but I think there's enough workarounds right now. Ah, ok, well at least I know what my first HDK project will be Thanks. Quote Link to comment Share on other sites More sharing options...
edward Posted January 19, 2007 Share Posted January 19, 2007 Yep, it should be easy esp. if you use chull. cf http://forums.odforce.net/index.php?showto...onvex&st=12 EDIT: I meant it's easy to incorporate their code. However, the algorithm is not the fastest. Actually, it might be pretty slow for huge amounts of points. But then computers are getting faster constantly anyhow. Quote Link to comment Share on other sites More sharing options...
Gordon Posted January 19, 2007 Author Share Posted January 19, 2007 Yep, it should be easy esp. if you use chull. cf http://forums.odforce.net/index.php?showto...onvex&st=12EDIT: I meant it's easy to incorporate their code. However, the algorithm is not the fastest. Actually, it might be pretty slow for huge amounts of points. But then computers are getting faster constantly anyhow. Well my goal isn't specifically to make a convex hull sop as quickly as possible but to get used to the HDK so I'll try scratch building it qhull is a pretty straightforward implementation so I'll try that one, if I can just stop screwing around long enough to write it Quote Link to comment Share on other sites More sharing options...
edward Posted January 19, 2007 Share Posted January 19, 2007 BTW, I should mention Martian Labs has a qhull implementation for Houdini here: http://martian-labs.com/martiantoolz/produ...?product=convex I couldn't find any pricing info on it though. You might want to email them. Quote Link to comment Share on other sites More sharing options...
Gordon Posted January 19, 2007 Author Share Posted January 19, 2007 BTW, I should mention Martian Labs has a qhull implementation for Houdini here:http://martian-labs.com/martiantoolz/produ...?product=convex I couldn't find any pricing info on it though. You might want to email them. Ah, guess that nixes qhull as an algorithm then. I didn't realise the Martian labs on was still available. Quote Link to comment Share on other sites More sharing options...
edward Posted January 19, 2007 Share Posted January 19, 2007 Not necessarily. There's always room for competing implementations. Don't let that deter you. It seems like to you their QHull SOP, you need to set up some sort of license thing at least. Quote Link to comment Share on other sites More sharing options...
davedjohnson Posted November 10, 2009 Share Posted November 10, 2009 Not necessarily. There's always room for competing implementations. Don't let that deter you. It seems like to you their QHull SOP, you need to set up some sort of license thing at least. So did anyone come up with anything recently? I had the Martian Labs one many years ago (we were the ones they built it for), but I couldn't get them to keep up with updates as Houdini grew. I'm pretty sure that we had it for version 4 or 5. I just got the qhull stuff and was able to compile it for standalone, but I can't figure out how to use the qconvex library stuff to wrap it into Houdini. Could someone tell me how to use the library? Dave Quote Link to comment Share on other sites More sharing options...
edward Posted November 10, 2009 Share Posted November 10, 2009 My last post regarding this was here: http://forums.odforc...dpost__p__19798 As noted, I just hacked their io.c file to output a valid .ply file header. It's just slightly better than manually hacking their output for reading into Houdini. As for some "newer" stuff, try the package here which I've header might have something useful: http://forums.odforce.net/index.php?/topic/9119-voronoi-dynamic-location-based-fracture-wip/page__view__findpost__p__64501 (I haven't tried looking) Quote Link to comment Share on other sites More sharing options...
petz Posted November 10, 2009 Share Posted November 10, 2009 i can´t help with qhull but for convex hull creation i have used tetgen in the past which works quite well. its robust an reasonable fast. have a look at the attachement. the included standalone is compiled for windows, so if you are on linux or mac, download tetgen from http://tetgen.berlios.de/. petz hull.rar Quote Link to comment Share on other sites More sharing options...
edward Posted November 10, 2009 Share Posted November 10, 2009 i can´t help with qhull but for convex hull creation i have used tetgen in the past which works quite well. Nice, and unlike qhull it reads/writes .ply files off the bat making it much more easier to use with Houdini. Quote Link to comment Share on other sites More sharing options...
Ratman Posted November 10, 2009 Share Posted November 10, 2009 The line count on those libraries almost made me faint. Quote Link to comment Share on other sites More sharing options...
edward Posted November 11, 2009 Share Posted November 11, 2009 If you want a *robust* convex hull implementation AND fast, then it's no trivial matter. Quote Link to comment Share on other sites More sharing options...
petz Posted November 11, 2009 Share Posted November 11, 2009 If you want a *robust* convex hull implementation AND fast, then it's no trivial matter. so then i would recommend the hull creation algorithm included in vtk if you don´t want to write your own. there are just two problems with this one. first is that it´s not too accurate and second, you have to have vtk installed what could be a bit tedious on some platforms. but regarding speed and robustness its definitely recommendable. for up to 1 mio. points it´s under 2 sec. attached is the file with embedded otl´s, but you NEED vtk to be installed for this. petz hull.hip Quote Link to comment Share on other sites More sharing options...
caleb Posted February 28, 2010 Share Posted February 28, 2010 Hey petz - thanks! I was looking for exactly this sort of example, and here it is. Quote Link to comment Share on other sites More sharing options...
sibarrick Posted March 1, 2010 Share Posted March 1, 2010 Any pointers on getting vtk working with Houdini python? I've basically downloaded and installed the vtk exe but how do I let Houdini know it's there? (Windows) Quote Link to comment Share on other sites More sharing options...
edward Posted March 2, 2010 Share Posted March 2, 2010 I don't know how you'd do this for VTK specifically, but in general (on Windows), I just follow the regular Python package instructions but substituting "hython" instead for python. If things need to put into a the python distribution directories, then I just put it into the corresponding directory under $HFS/python instead. Quote Link to comment Share on other sites More sharing options...
petz Posted March 2, 2010 Share Posted March 2, 2010 you have to compile it from source for python 2.5 instead of installing the exe file. then just do what edward said. petz Quote Link to comment Share on other sites More sharing options...
Jason Posted March 2, 2010 Share Posted March 2, 2010 If you're ambitious, you could try a CGAL interface? The document page for Convex Hulls: http://www.cgal.org/Manual/beta/doc_html/cgal_manual/Convex_hull_3/Chapter_main.html 2008 Google Talk Video: And an (older) python binding, in which it's unclear if it works right with Python 2.6+: http://cgal-python.gforge.inria.fr/ Quote Link to comment Share on other sites More sharing options...
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