deadpixel 4 Posted June 26, 2017 (edited) Hi I can successfully group unshared edges to get the boundary edges of a flat grid. However, how might I procedurally remove the very inside enclosed hole edges (such as the three holes in the attached image), and only have the very outside perimeter remain in the group? Any advice appreciated Edited June 26, 2017 by deadpixel Share this post Link to post Share on other sites
konstantin magnus 773 Posted June 26, 2017 Create a polyfill to close the holes for the time being, put them in a patch group under "Output Groups", and remove the primitives in "patch" group when you are done? 1 Share this post Link to post Share on other sites
animatrix 206 Posted June 26, 2017 There are many ways to do this but one way I would do is delete all groups but the largest one by element count using something like this: https://www.dropbox.com/s/lkl7j2w6r65r2im/DeleteGroupsByCount_SOP_Animatrix.otl?dl=1 1 Share this post Link to post Share on other sites
Noobini 687 Posted June 26, 2017 (edited) extremely easy............once you know how that is.... (in your case...you may have to select more than 1 groups because of 2 islands....so probably border__0 and border__1) Just in case youtoobe plays up and you can't watch...the gist of it is: 01) in your group select unshared edges...make sure you tick Create Boundary Groups, then if you have a 'normal' boundary plus 2 inside holes...=> you'd have 3 Boundary Groups 02) in your next group select, in the dropdown list you'd see border__0, border__1, border__2, ....border__0 should be the outside one...the other 2 would be the holes..you can go nuts with all sorts of permutation/combinations with your group selections... Now you know how easy it is....just say OMG !!! Edited June 27, 2017 by Noobini 4 Share this post Link to post Share on other sites
deadpixel 4 Posted June 27, 2017 Ah it is so absurdly easy, thank you guys!! My problem stemmed from a situation where I couldn't actually select Create Boundary Groups as it was greyed out in the group node...so I overlooked it.... but it turns out this was because I had set to group 'edges' and not to 'points' Thanks again, these are all great options, and I really appreciate the time taken! Share this post Link to post Share on other sites
deadpixel 4 Posted June 27, 2017 (edited) Interestingly the third enclosed hole does provide a bit of a conundrum... ...polyfill doesn't recognise it as a hole, and the boundary groups isolate the two main outer islands, but seemingly no shared points. My need would be to make sure all 'inside/enclosed' edges are removed from the very outside perimeter group. Ive just tried messing about with group combine to see if there are some logical combinations of the point group that could isolate it, but not much luck so far A few ideas I'm intending to test when I'm back at my computer would be to promote the group to edges/prims and try a combination of shared points to try to isolate it, or possibly by vertex count of the points....any thoughts? Edited June 27, 2017 by deadpixel Share this post Link to post Share on other sites
Noobini 687 Posted June 27, 2017 just did quick a test to see what would happen if the inside boundary length is LONGER than the outside one...from the result...I would say it's safe to simply pick the first one (if you want the outside, with no other islands) ie....xxx__0 group. 1 Share this post Link to post Share on other sites
Noobini 687 Posted June 27, 2017 6 minutes ago, deadpixel said: Interestingly the third enclosed hole does provide a bit of a conundrum... ...polyfill doesn't recognise it as a hole, and the boundary groups isolate the two main outer islands, but seemingly no shared points. My need would be to make sure all 'inside/enclosed' edges are removed from the very outside perimeter group. Ive just tried messing about with group combine to see if there are some logical combinations of the point group that could isolate it, but not much luck so far A few ideas I'm intending to test when I'm back at my computer would be to promote the group to edges/prims and try a combination of shared points to try to isolate it, or possibly by vertex count of the points....any thoughts? so in this case doesn't select groups xxx__0 and xxx__1 do the job ? Share this post Link to post Share on other sites
deadpixel 4 Posted June 27, 2017 14 minutes ago, Noobini said: so in this case doesn't select groups xxx__0 and xxx__1 do the job ? No, as it also includes two points inside 3 that are not part of the very outer perimeter (if you consider the two main islands to be connected and 3 to be a hole inside) Share this post Link to post Share on other sites
Noobini 687 Posted June 27, 2017 mmm....I could argue that is is correct coz there's TWO outside boundaries...each and every one of those 4 pts in 'hole' 3 (and I agree with polyfill here that 3 is NOT a hole) is on the very outer perimeter...but yeah for what you want to deselect the 2 diagonal ones...it's tricky....procedurally... Share this post Link to post Share on other sites
deadpixel 4 Posted June 27, 2017 Yeah totally appreciate it is not reallly a 'hole' my thoughts are something along the lines of vertex/nearest-point count to isolate the diagonal on the enclosure...will have to try when back at houdini Share this post Link to post Share on other sites
Noobini 687 Posted June 27, 2017 I'm leaning towards exploiting VDB (or anything volume based)...coz those 2 pts would be 'enclosed'...but am not competent enough with VDB I'm afraid... Share this post Link to post Share on other sites
Noobini 687 Posted June 27, 2017 (edited) YES...done it !!! I will not be defeated... SelectOutsidePoints.hipnc Edited June 27, 2017 by Noobini 2 1 Share this post Link to post Share on other sites
deadpixel 4 Posted June 27, 2017 2 hours ago, Noobini said: YES...done it !!! I will not be defeated... ha, nice idea ! Ill test when I get back home to see how it holds up to a few ideas I have thanks Noobini! Share this post Link to post Share on other sites
deadpixel 4 Posted June 27, 2017 works a treat so far thanks! really appreciate it Share this post Link to post Share on other sites
Krion 3 Posted May 19, 2019 Hi guys.. How does one convert them to edges? Share this post Link to post Share on other sites
Noobini 687 Posted July 23, 2020 usually grouppromote, then you may need to experiment with Include Only Elements on the Boundary or Include Only Elements Contained in Orig Group. but in simple cases where there are no holes, why don't you just select unshared edges in the first place ? Share this post Link to post Share on other sites
vinyvince 44 Posted July 30, 2020 Hey guys To fix some Voronoid cluster issue, im trying to heal some edge hole problem in the middle on my assembly. I was thinking to go from world space to a planar UV space to extract the boundary of my mesh but the polyexpand2d fail to works and On 27/06/2017 at 12:14 AM, animatrix said: There are many ways to do this but one way I would do is delete all groups but the largest one by element count using something like this: https://www.dropbox.com/s/lkl7j2w6r65r2im/DeleteGroupsByCount_SOP_Animatrix.otl?dl=1 Is that expansive to do a loop check for all possible prim group and keep the latest one? In planar, i think i could isolate the disconnected pieces, do a bound with a rectangle, resample it than do a ray sop to wrap and get the outside border. I guess it should work Overall, if i tried different approaches from building these procedural patterns, in this setup im using something similar to Matt Estala Voronoid setup for H17 as a base https://www.tokeru.com/cgwiki/?title=Houdini As soon as the number of scatter points increase, It creates all these disconnected problems shown here which i didn't expect for such a basic setup... I wish i could also have scales xyw attributes to have a slighty better control for the cluster shape like in the old h16 voronoid Did i miss something? How you usually deal with that on a custom input form. using Voronoi (Here i tried to avoid, VEX define pattern, Cops, Pop) Thanks guys, take care ________________________________________________________________ Vincent Thomas (VFX and Art since 1998) Senior Env and Lighting artist & Houdini generalist & Creative Concepts (Available) https://www.imdb.com/name/nm0859628/ http://fr.linkedin.com/in/vincentthomas Share this post Link to post Share on other sites
vinyvince 44 Posted July 30, 2020 (edited) Answer to one of my own question, just remember the RBDcluster actually allow to have more control of the cluster area definition... No really impressed too by the SideFx Lab subdivid lot... Edited July 30, 2020 by vinyvince Share this post Link to post Share on other sites
vinyvince 44 Posted July 30, 2020 I tried a different approach on our couple Pig & Squid, i could get large polish hard surface plate but still like to find out , hmm. ________________________________________________________________________________________________________ Vincent Thomas (VFX and Art since 1998) Senior Env and Lighting artist & Houdini generalist & Creative Concepts (Open for new opportunity) http://fr.linkedin.com/in/vincentthomas http://fr.linkedin.com/in/vincentthomas Share this post Link to post Share on other sites
