Creating a Surface with Edge Kinks


#1

This is a problem that I have encountered several times and am looking for a generic solution that does not take hours.

Problem Plating.3dm (3.0 MB)

I am trying to reproduce the superstructure here. The sides are generally lines. However the top has kinks at the stern. IN order for the plating to be smooth, the vertical profiles cannot be straight at the kinks.

The starting point looks like this:

My question then: is there some simply way to generate a useable surface form these profiles that is smooth through the kinks?


(John Brock) #2

No, not a single surface unless it is a trimmed surface.
The notch in the top left can be cut away, and the long curved bottom can be trimmed.
The underlying untrimmed NURBS surface has 4 sides.


#3

When you are building a model ship 3d, air, car and so on. it is essential to carefully choose the documents to be used as a reference. In this case, I would start from the main sights. This would say that would be fine:

(quickly found on Google images) I would say that there are already 90% of the information you need. Only then you can use the photos (keeping in mind that the photos have distortions due to perspective).
If volglio save hours of modeling, it invests a lot of time in the documentation.
My 2 cents


(John Brock) #4

The User’s Guide has a good tutorial called Trace Images (the subject is a dragonfly), that goes over the techniques used when building a 3d model from top and side images.
http://docs.mcneel.com/rhino/5/usersguide/en-us/index.htm


#5

For this area, I was actually able to get tabular data. This tabular data is consistent with the plan posted above. The problem is, as in the plan, there are kinks in the profile.

The sides are mostly straight. However, builders would have had to slightly bend the plates outwards to make a smooth transition over the kinks.

In the past I have done tedious trial and error trying to find the amount of bending required in these kink situations.

I was wondering if there was some easy way to find the amount of bending required without lengthy trial and error.


#6

Here is one I made in a different project where I had the same problem (with only one kink).

The green and black to the right of the green are the cop edge and the red is the bottom edge. The 10 blue curves at the right are lines. The 12 blues at the left are non-linear curves. I extended the surface up and down then I tediously adjusted the curves until they produced a smooth surface.

I was trying to find a simpler way of determining the curvature.


#7

After much tweaking of curves this it what I ended up with. There has to be an easier way though.


#8

Because of my bad english I find it hard to explain.
I hope the help file.
Basically.

  1. use of a degree curves 5 and 7 control points for the surface.
  2. activating the history of construction and then sweep 1. act on the curves of the control point and the surface will change accordingly. Use ONLY the original curves as a reference.
    The file I enter here does not correspond to the real model, in particular in the conjunction point of the island to the hull. use the handles to get the desired result.
    Problem Plating.3dm (13.1 MB)


#9

Thanks for all the effort here! I am going through all of this now.