magneto Posted December 27, 2015 Share Posted December 27, 2015 Hi, I know VDB Analysis does this but is there a way to calculate this manually in VOPs? Merry Christmas Quote Link to comment Share on other sites More sharing options...
TheDude Posted January 5, 2016 Share Posted January 5, 2016 Merry Xmas! The way I'd do this right now would be to put a point per voxel, and then check the dot product of local points sdf vector vs its own and reproject back that onto a new field... But that seems pretty inefficient, betting there's a much better way! 2 Quote Link to comment Share on other sites More sharing options...
magneto Posted January 10, 2016 Author Share Posted January 10, 2016 Thanks but I am trying to figure out how to implement the math way in VOPs practice Quote Link to comment Share on other sites More sharing options...
fathom Posted January 11, 2016 Share Posted January 11, 2016 what kind of volume? if it's a fog volume, you can get the density gradient and then compute a dot product against a neighboring position. Quote Link to comment Share on other sites More sharing options...
magneto Posted January 19, 2016 Author Share Posted January 19, 2016 Any scalar field, because that's what Analysis SOPs support. I will try your suggestion. Is this the appropriate way to calculate curvature? Quote Link to comment Share on other sites More sharing options...
fathom Posted January 19, 2016 Share Posted January 19, 2016 Is this the appropriate way to calculate curvature? no idea at all. Quote Link to comment Share on other sites More sharing options...
magneto Posted February 14, 2016 Author Share Posted February 14, 2016 Any math gurus who can show this in VOPs? Quote Link to comment Share on other sites More sharing options...
Popular Post petz Posted February 19, 2016 Popular Post Share Posted February 19, 2016 curvature computation on grid data like volumes is fairly easy. just compute the hessian and extract the curvature information you need. hth. petz vol_curv.hipnc 13 Quote Link to comment Share on other sites More sharing options...
danw Posted March 31, 2016 Share Posted March 31, 2016 curvature computation on grid data like volumes is fairly easy. just compute the hessian and extract the curvature information you need. hth. petz Just want to say thanks for that petz, exactly the information I was looking for, clear and elegantly demonstrated :-) Quote Link to comment Share on other sites More sharing options...
tagosaku Posted April 19, 2018 Share Posted April 19, 2018 I recently checked file "vol_curv.hipnc" and that's great, and I wonder if we can always output a normalized value. It would be a range mostly -1 to 1, probably using voxel size info . I know it could be depends on polygon object and value could not reach max1 ot min-1 value. Right now, for instance, it sets vdbfrompolygons1>voxel 0.2, and curvature range -1 to 10. When it sets voxel size to 0.1, curvature range become -3 to 14, etc. I know, after calculating curvature, we can normalize it by fit node. But it would be great to output normalized curvature approximatly -1 to 1 in all the time, regardless voxel size. Thanks Quote Link to comment Share on other sites More sharing options...
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