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lofting freezes rhino 2.0


New member
Im trying to loft a series of polylines contained in an iges file. The lines are circular (not perfectly but form a loop) and stacked vertically, one on top of the other. The radius of the lines increase as you travel in one direction, they were obtained from a Ct scan and represent the inner canal of a human bone. Now when i try to loft this structure the function begins to run but after a time the program freezes. Can anyone tell me what I need to do with the loft function to get it to work, or what other functions to use.

I have also tried using the surface function by entering a cloud of pts but it requires equal number of pts on each level, which i dont have. If i attempt to interpolate pts into my file (so that i have an equal number of pts on each level) the surface which the function produces has very irregular normals.

Does anyone have suggestions?

Thank You


  • polylines2.bmp
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Making a model with scan data

There are several things you can do, but the first place to start is here:

Reverse Engineering

If I was doing this, I would eliminate about 75% of the cross-sections. Then I would make sure each one was closed. Then I would rebuild them to degree 3 and within some reasonable tolerance. Then I would try to loft them. As a test, try to loft 3 or 4 of the cross-sections you have, just to see if it will work.

If that works, try to add a few more cross-sections.

One of the biggest problems with geometry like you have is that some of the cross-sections are either too close together or right on top of each other.

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