Tricky Intersections and Endings



Hi everyone. First time poster here. Love the content.
I’ve used Rhino for a long time in my job, but mostly always had to model simple geometric shapes and scenes, so this is a tricky project for me. I hope this could help others with these more complicated shapes. I modeled this in nurbs and haven’t yet explored subd, so that wasn’t really an option for me at this time.

Red circles:
Does anyone know how to get more fluid intersections of the surfaces in the red circles? The This is the best I’ve been able to do, but in my mind I picture one archway merge with perfect tangency into the second (larger) archway. I couldn’t manage to get it, so after many hours just decided to make the smaller archway shrink down before intersecting the bigger one.

Blue circles:
I tried multiple ways to cap these scripted letters at the ends. Loft with three or four profile curves (top blue circle) or surface from network curves (lower blue circle). The lower circle I even trimmed back the main surface and did a blendsrf on tangency to try and get a perfectly tangent seam. I can get pretty close, but would appreciate any input that helps get the surface perfect in the zebra or emap analysis.

Green circles:
Just another example of different shapes that share one common surface. Ideally, I would like the common side (right side) of both surfaces to blend perfectly, but the best I could do was adjust surface edit points to get the surfaces “close”. Any help is appreciated.

dear @rkwill

if you post a .3dm file, it will be easier to help.

red circles:

the (hierarchical) y-branch (search in the forum and google) should be possible with
_blendSrf
you need to spend some effort in a nice curve setting for trimming.
… aslo depending on the design intention.

blue circles / curved caps
also this is possible with
_blendSrf
but really depends on the effort and time you want to spent.
other approach may use
_netWorkSrf ( i don t like)
_loft or _edgeSrf combined with control point editing ( i would give a try)
_patch ( if you re really in a hurry)

… and no doubt … for sure someone will argue for Sub-D modelling…

kind regards -tom

Thanks Tom_P for your answers.
As per your suggestion, here’s the 3dm file.

Choisi.3dm (3.3 MB)

something like this ? for the red (circle in initial post ?) transition / blend ?

as long as you have this quite sharp ridge - this might be quite difficult.

you have to experiment with a method to trim both surfaces (1)
and then to get the blend-Surface (2)

in the example i did:
(1)
_mergeSrf the initial Surface to have only a single surface / edge
_offsetSrf → and use this surfaces to trim

(2)
_blendSrf might give a result in one go but i used it in 2 steps:
_blendSrf with position - adding a few shapes. (this will give a ruled surface, with position continuity similar to a loft)
_changeDegree 3,5
_matchSrf (curvature)

… it depends a bit what you need the data for (rendering, production, fast or precise…)

kind regards -tom

Hello - I think you may be able to get away with FilletSrf here for the transitions-
R = .2 here -
image

image

For the ends, I think collapsing all the end control points to the mid point between the ends of the next row is simple and will be fairly consitent, rather than adding a tip.:

All of this will be simpler if you can build the surfaces as a single surface in the ‘short’ directiion.
image

-Pascal

1 Like

Thanks a bunch Tom. I’ve been trying to follow you example all morning until I realized _matchsrf has a “MultipleMatches” option. I was trying to do one side at a time and getting poor results. As soon as I used MultipleMatches the surface behaved much nicer. You are right though about experimenting with how to trim both surfaces. I liked the result when I trimmed a half circle out of the larger surface quite a bit larger than the intersecting shape. It allowed for a nicer blended surface with curvature constraints. Thanks again.

Thanks Pascal for the tip about collapsing all the points on the end caps to a single point/location. The resulting cap looked very clean with minimal effort. I’ve never thought about working with the surface like this and it worked really well. Thanks!