I’m working with the Patch command in Rhino to generate a surface from cloised curves. surface appears to float away from the input curves, especially (see screenshots).
I’ve also tried lowering the spacing value and increasing stiffness, but the surface still doesn’t stay tight to the boundary in some areas.
I would appreciate any tips on how to force the surface to follow the curves more closely, or suggestions for better approaches if Patch isn’t ideal for this.
The right way with patch is try to be more logical, add the Sufficient number of UVs, but most importantly is to visualize it first in yr mind, try to make it simple at first, with the main profiles you need, then edit it, since patch isn’t an accurate parametric tool, it’s more concedered as a surface drafting one, so you develop it after you patch, so break the organic surface that you want to model into simpler steps for rhino, curve profiles, contoured curves, increase UV spans, grid points may help too, try to cut it into more simpler surfaces and then join them, could also use mesh tools or subd then convert them back to nurbs, and so on,
You could try to loft multiple horizonal curves contoured on yr shape outline resulted from patch.
patch curves to get the non sticking surface you want
contour surface
loft curves in order
That would give much cleaner result
And finally as i see, this is a roof design i think, which should be connected with facade outline that should be connected at the same points to have no gaps. If I’m right, it would be easier to adjust the facade or the walls which will be simple section profiled geometries, that could be easily adjusted to the roof than tk adjust the complex roof you designed to them, so inverse the workflow if nothing works with you,
design the roof with any similar outline you want
edit pts, cage edit, subdivide and create the désirable roof form with any outline
dubface edges for the surface you created
project it into 2d
extrude and trim extended surfaces
then it gonna be easily adjusted surface to connected surfaces to it’s outline
If the shape has four sides you can use Patch with a starting surface and preserve the edges of the starting surface.
Use EdgeSrf with the four edge curves as inputs to create an initial surface. I put this surface on a different layer than the layer the final surface will be on.
Make the layer for the final surface the active layer.
Start Patch command and select the input curves and points.
Click on “Select Starting Surface” and select the initial surface.
Click on “Preserve edges” If it is not selected.
Enter to complete Patch
If the result does not fit the interior curves and points close enough, or is wrinkled etc, then use InsertKnot to insert control points in the initial surface and repeat the process above.
In my case, the patch I’m working on is actually a pretty small part of the overall model — and I totally get your point about simplifying things and adding more profiles to guide the shape better. That really helps Rhino generate a more predictable surface. But I’m running into two specific issues:
The patch surface gets disconnected from the input curves – even if the result looks roughly okay, it doesn’t stick properly to the boundary lines.
On the last screenshot (you can see it), the patch behaves like a stretched rubber sheet or even like water – there’s a strong distortion right in the center. I’m not sure what causes that, because the input curves are simple and clean.
