I thought I would dig out an old project I never finished, now that I’ve got Rhino 7, and see if I can resolve it with Subdivision surfaces.
It’s a double-ended wooden ferry built in 1912. As the original ship’s lines drawing shows, it had an unusual semi-chine at the end. The uppersides to project over the rudder, while the lower hull finish just short of the rudder.
Some time ago, I had tried to model this in Maxsurf and bring the nurbs surfaces into Rhino. It never really worked. The problem was that I could only create the hull in a top and bottom section, and could never properly stitch them together while maintaining continuity. (Note also there are separate skeg and keel surfaces). My second screen shot is that nurbs hull.
My third screenshot is the nurbs hull converted to SubD, with all surfaces stitched together. At first sight it looks ok – as in, it does hang together as a single surface, but the continuity is awful. I don’t need great precision vis a vis the original, but I am aiming for a reasonably fair surface.
What I’d like to know is, since I’m only a raw beginner on SubD (just watched the tutorials and that’s about it), how best to go about fixing it? All my attempts so far just stuff it up even more.
Hi Ian - This does not address your SubD questions at all but, I am not sure exactly what is wrong with the surface version - there are some ‘goofy’ maxSrf surfaces in there that can be replaced in Rhino with planar faces - the main thing is the front bit where the chine carries on perhaps more than you like?
That can be tuned up by slight adjustments to these points:
I guess that chine still fades a little too late but maybe a little better - it would be easier with a higher degree surface, it seems to me, to keep things clean - 2 is unusual from a Rhino perspective, but I know almost nothing about how MaxSrf works…
I am a Masters in Yacht Design student from Politecnico di Milano. I am working on my thesis project of a semi-chined hull modelled in Maxsurf, and I am experiencing the same problem as well. The boat is going to be built out of wood, and part of the assignment is to do a structural model of the boat. With this, I need to do offsets of the surface that is imported into Rhino from Maxsurf. The hull in Maxsurf is made from compacted control points to form the chine, and Rhino does not recognize the hull side and the hull bottom as individual surfaces or the edge of the chine which leads to problems.
My goal is to model the structure using Grasshopper, so I can modify the thickness of the hull as needed while working with structural regulations. I would need to get this surface fixed to start modelling the veneers and strip planking of the hull. Here is a picture of the problem.
Hi Caine - - I do not see a good way out starting from a single kinked surface. A not good way out might be to split the surface with an isocurve at the kink and shrink the results, but the edge will still have stacked control points and removing them will modify the shape. Or live with the unhappy offset until everything else is correct then fix that…
