Hi everybody, I am doing a brain modeling project and would like to interpolate between different contour lines to form a volume. Any suggestions? 27.00_to_30.60Brain.3dm (156.6 KB)
Loft was my first thought, and using the rebuild option might yield the most manageable surface structure due to differing control point counts. If you ultimately need a solid volume, OffsetSrf with the Solid option can get you there after the loft. Having cross section curves in the perpendicular direction would help guide the surface in the sharp corners as well… not sure if you can make these up or if they would have to come from the CT data.
Thanks Brian! The general shape of the brain surface I am modeling (the cerebellum) is fairly accurate. I used a “loose” loft command with a rebuild for fewer control points on similar brain sections. Then I used a “straight” loft command to join the sections. This gave a much better representation of the cerebellum’s shape as opposed to one big loft, but it produced sharp surfaces that I would like to smooth without sacrificing its accuracy.
Do you know of a way to do this post-loft? Surface fillets haven’t worked that well. Or do you think I should keep playing with the curves’ settings before lofting?
Cb_Surface _1.3dm (1.4 MB)
I’d keep it all as one surface if having a smooth surface is desired. Here’s a loft with the Normal style and rebuilt with 200 points.
Cb_Surface _1_BrianJ.3dm (1.9 MB)
Any good? I suppose what you’re actually doing with the model is the ultimate criteria. I’d love to see the full scan if you can share it… very cool.
Hey again Brian, sorry for the late reply. You were right, one big loft over the contours produced a smooth body for the cerebellar structure. However, at the very back of the cerebellum, its structure splits into two distinct regions (forming a closed curve on one of them); therefore, I cannot include these last few contours in my original loft. I had to perform a separate loft on them. But, now my structure has a sharp edge dividing the two lofts. What would you recommend? Cerebellum_July9.3dm (2.2 MB)
To answer your question, my end goal is to superimpose the model on top of a 3D MR image for a macaque monkey. Here’s what it currently looks like:
Okay, this is pretty abstract as far as geometry is concerned but it’s possible to smooth out the intersections you have so far using a combination of SplitEdge, BlendSrf and NetworkSrf. It will require using the add shapes option in BlendSrf and tweeking the shape curves using the Alt key while clicking and dragging to change the edge angle of the blend ends. For the gaps you have after a few blends, use NetworkSrf set to tangency.
Honestly if this is all for visualization, it’d be easier to make overlapping meshes, Boolean them together and use Smooth and ReduceMesh to soften the edges. Or export to a mesh specific modeling program with sculpting tools for smoothing.
Here’s the NURBS version showing the steps I described above too…
Cerebellum_July9_BrianJ.3dm (5.3 MB)
Looks great, thanks for your help.