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I load a custom region, specified as BoundaryMeshRegion

R = Import["C:\\data\\Profile.stl", "BoundaryMeshRegion"]

region import

and I try to find an intersection

intersection = RegionIntersection[R, InfiniteLine[RegionCentroid[R], {1, 0, 0}]]
RegionMeasure[intersection]

Where

region bounds

And I get errors:

intersection errors

Is this supposed to work ? I can't figure out what I am doing wrong, here's all the troubleshooting I could think of:

region troubleshooting

I would really appreciate any tips on what I am doing wrong, this functionality works with standard regions like Ball[], I would really like this to work on my region too!

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  • 2
    $\begingroup$ Please try to upload Profile.stl somewhere; your question is unanswerable otherwise. $\endgroup$
    – J. M.'s lack of A.I. ♦
    Oct 12, 2018 at 15:05
  • $\begingroup$ File added ufile.io/jo8j6 ! $\endgroup$
    – Anatoly
    Oct 12, 2018 at 19:12
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    $\begingroup$ It seems like there's no intersection: Show[{R, DiscretizeRegion[InfiniteLine[RegionCentroid[R], {0, 0, 1}], RegionBounds[R]]}] $\endgroup$
    – halmir
    Oct 15, 2018 at 13:07
  • $\begingroup$ Thank you @halmir for pointing that out! I changed line direction to {1,0,0} to make sure they do cross, still same error though :( Line direction {0,1,0} produces the same error again $\endgroup$
    – Anatoly
    Oct 15, 2018 at 19:39

1 Answer 1

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As a workaround, you could take boundary polygons and find intersection:

poly = Polygon[MeshPrimitives[R, 2][[All, 1]]];

line = InfiniteLine[RegionCentroid[R], {1, 0, 0}];

intersection = 
  RegionIntersection[poly, 
   InfiniteLine[RegionCentroid[R], {1, 0, 0}]];

RegionMeasure[Line @@ intersection]

33.6465

or to reduce computation time:

polys = MeshPrimitives[R, 2];

ipolys = Pick[polys, RegionDisjoint[line, #] & /@ polys, False];

intersection = RegionIntersection[line, Polygon@ipolys[[All, 1]]]
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  • $\begingroup$ Thank you @halmir, this works! I can use it as a workaround for now, after I figure out what it does :) $\endgroup$
    – Anatoly
    Oct 17, 2018 at 13:37

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