Surfaces that won't intersect

unhandled

#1

Here are a few surfaces that are returning 0 intersections, in V5 or V6.

Jimno intersections.3dm (14.2 KB)


(Pascal Golay) #2

Hi Jim - thanks, I’ll add these to the heap - looks like there is a knotline right on the intersection planes.

https://mcneel.myjetbrains.com/youtrack/issue/RH-44916

-Pascal


(B Design Bg2) #3

Another example of surfaces that clearly intersect to each other, but Rhino 6 can’t build an intersection curve with the “! _Intersect” command. If I untrim the white surface or use “! _RebuildEdges”, the intersection works properly. However, the “! _RebuildEdges” command creates issues with other surfaces. For some reason the bottom edge of the white surface has some problematic split spot, even though it was split by a simple surface (the red one).

Intersect objects.3dm (171.2 KB)


(Pascal Golay) #4

Hello - edge tolerances are very large on the white object (What command) -

Edge Tolerances: 0.0001149 to 14.1683818
median = 0.0004393 average = 3.5424014
Vertex Tolerances: 0.0000000 to 14.1825501
median = 0.0000087 average = 1.7728973

I’d DupBorder, Untrim and then re-trim that surface.

-Pascal


(B Design Bg2) #5

Hi Pascal, thank you for the quick response! I have no idea why the edge tolerances are up to the giant 14.1683818 mm deviation. I split the white surface with a few other surfaces (meaning no projected curves or split curves were used, only surfaces), and the absolute tolerance is 0.001 mm.

Meantime, I solved the issue by using the “Replace surface edge” command with “replaceWithLine” option on the bottom edge of the white surface, then I ran again the “Split” command using the red surface, then merged the edge with “Merge edge”, and this time the result looks proper. Revorking only the bottom edge allowed me to keep all the other edges of the white surface intact. I noticed that sometimes using “DupBorder” for splitting will slightly move the split suprface’s border, most likely because it uses some kind of approximation. I had numerous cases where surfaces that were split with duplicated border were no longer able to join to adjacent surfaces. Here is a comparison between:

  1. The original surface:

    8 boundary edges
    Edge Tolerances: 0.0001149 to 14.1683818
    median = 0.0004393 average = 3.5424014
    Vertex Tolerances: 0.0000000 to 14.1825501
    median = 0.0000087 average = 1.7728973

  2. The surface split with duplicated border:

    3 boundary edges
    Edge Tolerances: 0.0002271 to 0.0006177
    median = 0.0003621 average = 0.0004023
    Vertex Tolerances: 0.0000106 to 0.0002273
    median = 0.0000260 average = 0.0000880

  3. The surface whose bottom edge I first untrimmed, then split with the red surface:

    7 boundary edges
    Edge Tolerances: 0.0000214 to 0.0009988
    median = 0.0002739 average = 0.0003528
    Vertex Tolerances: 0.0000000 to 0.0005887
    median = 0.0000005 average = 0.0000897