Modify a lofted surface with another curve workflow?

Rhino Rhino for Mac
1

Hello,
I have lofted a surface from six open curves. Is there a recommended workflow to modify the surface to fit with an additional curve, perpendicular to the 6 curves used for the loft? Or is the better workflow to use all curves and the Patch command?
Thank you,
PaulFit_surface_small.3dm (230.3 KB)

Fit_surface.jpg691Ă—559 22.7 KB

2

Try this proceedure:

Create a preliminary surface using Loft and the 6 curves A single surface, not a polysurface, If the result is a polysurface explode the polysurface into individual surfaces, use MatchSrf to match the surfaces, then use MergeSrf to merge the individual surfaces into a single surface.

Run Patch with the 6 curves plus the added curves as input. Use the preliminary surface made in the previous step as the “starting surface”. Experiment with different values of “stiffness”, and with “Preserve edges” on and off

1 Like
3

Thank you, David. That is really useful. I would not have known about loft generating a polysurface rather than a single surface.
I used the MatchSrf for all of the surface panels and then used MergeSrf. This generates a single, open surface. (I’ve uploaded the merged model.)
I experimented with Patch after. This is where I ran into an issue: if I Patch the curves, I get a new surface; if I Patch using the curves, then select the merged surface as the starting surface, Patch just continues running and doesn’t generate a surface (might be my machine?). Or maybe I have carried out the match and merge steps incorrectly (I haven’t used this workflow before)? I checked with zebra mapping and the resultant merged surface looked good.
Thanks,
Paul.Fit_surface_small_match_merge.3dm (331.5 KB)

4

Your units are meters, the bounding box for the curves is 23161 m or 23 km long, and the objects are located 4733924 m or 4734 km from the origin.

Change units to kilometers and rescale. Move the objects so that they are within several hundred units of the origin. Rhino

For sample point spacing using a spacing around 1/10 to 1/200 of the length of the curves. The spacing of 0.05 m is creating a half million or so sample points which is why the command runs “forever”. For this project 0.1 km is appropriate.

5

Many thanks, David. Really appreciate the advice.