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xxyxxy

Smooth outline of 2D pointcloud

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Posted (edited)

I feel like I am missing something basic here -- I have a 2D pointcloud of a foot and I need a smooth 2D outline of it.  Shrinkwrap SOP and friends turn it into a convex shape which is no bueno and Triangulate 2D SOP also creates edges that ruins the 2D pointcloud silhouette.   

I thought maybe the Fit SOP would do it for me but I don't know how to give it just the silhouette points of the pointcloud.

I also have some ideas about using volumes and booleans to achieve this but I swear I've seen this done with simple point and triangle SOPs before.  Any ideas?  Screenie and HIP attached.

 

nr_foot_outline.png

nr_foot_outline.hip

Edited by xxyxxy
updated hip

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I'm sure there are more elegant methods, but as long as your shape isn't to concave, create a bunch of edges from your points with connect adjacent pieces sop and then create a circle bigger than your shape with inward normals. After that use the Ray sop to conform it to your shape.

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Posted (edited)

Next thing I'd test is the point order to see if I can delete all but the edge points. Once you have that, just use an add sop to create a polyline.

Looks like the trickiness is coming from the fact that it's not a flat, nice 2d pointcloud. Looks more like a 3d pointcloud that's been crushed to 2d, which gives you those weird curvy bits on the edges. Maybe try a fuse sop to get rid of those weird bunches and then a triangulate 2d.

Edited by dgani
dumbness

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Posted (edited)

 

Quick test...maybe this helps...

kind regards

outline.JPG

nr_foot_outline_edit.hip

 

EDIT: 

Oh I see that I am using your output of the triangulate node which is not accurate representation of your footprint...hmm 

Edited by jon3de

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if connect adjacent points provides good enough outline for your pointcloud then you can as well just use Triangulate 2D + Divide SOP to get exact outline, which will even match outline points 

nr_foot_outline_alt.hiplc

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