Loft in two directions

I am new to design. I have this structure (below) which started as a point cloud. Each ‘slice’ contained perimeter points. I want to create a surface.

I used CurveThroughPt to plot closed curves on each slice (2 curves on the two slices that are split into two ‘segments’).

To create the surface I thought it would be best to use loft - which works great if I ignore the two segmented slices. As a brute force approach I can build a loft up to those slices and then build 2 new lofts from there. I was wondering if there was a better way to do it?

Thanks

I think I understand your question but correct me if not please… you have closed profiles to loft between but interspersed are slices with two closed profiles. In these areas the transition from single slice>double slice>single slice will require some decisions on how the form changes. This could be sharp or continuous but in either case will require manual modeling. The condition reminds me of this tutorial from way back… maybe it’ll help

Thanks, that link is kind of what I’m trying to do but I don’t think I can use the sweep method. The loft method gives me good results (I later smooth the surface). However I can’t figure out how to connect the small loft section to the rest of the structure. Looking at all the blend, merge, join surface commands I can never seem to select the lofted surface as a connecting point, only the individual curves.

Any ideas?

edit: If I continue the small loft down to the next slice, can I then delete any overlapping surface?

Can you post the model? In general, if you want to connect lofts, you’ll need to have a gap between them to BlendSrf or have sufficient overlap as to Trim and Join prior to FilletEdge.

My original point cloud with curves drawn on each slice
http://www.filedropper.com/curves

With the two separate lofts
http://www.filedropper.com/separatelofts

The shape of these curves and the distance between them certainly makes this more difficult than the pipe tutorial. There is a lot of room for interpretation too when considering how the two lofted surfaces would blend together. The first thing I’d suggest is to use fewer points for the slice curves or rebuild the curves. The density of them now adds a ton of surface detail and will slow down the display and create tighter areas/folds in the lofts.

In short, this is how I’d do it.

curves_bjames.3dm (1.4 MB)

Thanks a lot for that - your way does produce the results I was looking for.

I am trying to follow your steps but I’m having some trouble (complete beginner).

For NetworkSrf Rhino asks for at least three curves in each direction…I’m not sure which ones I am supposed to pick. I also notice there area few curves going between slices - is this something I put in manually or is it created from NetworkSrf?

Sorry, I didn’t cover that step. Yes, you would need to add those curves that run perpendicular using InterpCrv and Near Osnaps. Then you can select the curves in any order. These curves keep the surface from twisting as it will with Loft alone.

Thanks. I managed to get to the last step, but I am stuck again.

I’m not sure what the InterpCrvOnSrf step is doing. Which surface are you selecting? I’m assuming I am trying to add a curve on top of the hole in the middle?

The purpose of this bit is to make the sides of the hole non-planar. The two surfaces to either side are selected individually and a three point curve interpolated on each surface is drawn. These curves are then used to trim each of the surfaces. You can Explode or ExtractSrf each surface if needed to get the trim to work. The logic is that if we want tangent continuity to the adjacent surfaces with the final NetworkSrf, we need to have curved edges meeting at the corners.

Ahh! Great. All done.

Thanks for your help!