Create Surface from an Odd Shape

Problem54.3dm (52.3 KB)

In the attached I have a set of curves that I need to use to create a surface. This is part part of a larger surface. The curve to the left and top join smoothly with adjacent panels.

The curves to the right and bottom are ends and the surfaces that join there meet at right angles.

This shape (at least as is) does not work with networksrf or sweep2. What is the best way to handle this?


You could try Extending the trimmed curves on the right hand side of your picture past the top and bottom lines with the Smooth option enabled, Trim the curves to the top and bottom boundary line, then Loft the curves to create the surface and Trim out the sections on the right hand side of the picture as the final step. You’re left with a complex surface but it seems to track the input curves pretty well.


It works with Network as well, although you probably won’t be able to do much modification without simplifying your input curves to leave you with a more manageable surface.

You can use Split command(split at point) to split the top and bottom curve at the intersection of the vertical lines using snap.
Then sweep2 can be applied.

Problem54_sweep2.3dm (80.0 KB)

In regard to extending, the problem would be how to do that. The curve is at the end of the hull and needs to have a constant with with the same curve on the other side of the hull. How would one do that.

In regard to sweeps, the issue is how to get around the same curve.

Hi Jim - try ExtendCurve - it is an undocumented test command but it might help with what you are doing better than Extend.


What does ExtendCurve do? I don’t have access to Hillary’s email serve to find such top secret information.

I asked and Hillary says it does not do anything at all unless you type it in and try it.


I’m missing the Top Secret document that tells how to get it to extend on the other side.

Well, that actually requires you to read the :secret: command line prompt. :expressionless:

Ah… I got the sittation now.
Is the left and top surface available to use?

Am I missing something? I don’t see anything in the prompt?

This shows the available surfaces. In addition, there is an and additional surface that will go at right angles (coming out from the picture) to the bottom edge (flat for a short distance, sloping up, near vertical, following the crescent, then going to the stern.

The top is then the only naked edge.

Here are some pictures with the surrounding pieces to illustrate

Here you can see that the piece above. There is a tunnel that forms the back side of the piece above. The tunnel and the outside are joined by half siding (surfaces that are perpendicular to the centerline). This view is from the opposite side of the one in the post above.

This is more a top view of the piece above showing the tunnel and the hull.

I was thinking of using edges as reference for the sweep2 or networksrf.
If rebuilding the horizontal lines are ok…

Make a line on the adjacent surface by projecting a curve,

Use blendcrv to blend curve to get a tangency.

Use splitedge at the intersect of curves and adjacent tangent surface edge to get a short curve.
Then use the edge as one of the rails for the sweep2.
Now the option is available to choose tangency for the edge.

Not sure if this is efficient… but seems to work…
–networksrf seems better to get other sides tangency as well, just need few more lines across.

By using networksrf;
(sorry I said splitedges, but to do networksrf each of the surface edges needs to be one edge.
so mergeedge or mergealledges if surface edges are split apart.)

all the reference curves are blended to a curve projected to the surface.