Getting a polysurface to behave like a mesh


Im pretty new to all of this and I’ve made something and only realised LOADS of actions after the fact
that I have mismatching corners and need to align them. Problem is, they are all trimmed surfaces and
have been made to polysurfaces. Okay- I tried exploding and shrinking the surfaces but the points still don’t lie on the corners. I converted to a mesh, but that makes the whole thing , well, really just not what I want! Any ideas?


I would explode the polysurface and reconstruct the only problematic Srf with sweep command. and then match the rest of the Srf with the new sweep.
the thing about NURBS is that if the trimmed Edge is connected to another Srf, u will have to reconstruct it back if u made a mistake or if u want to modify some joints. using construction history sometimes can come in handy, but sadly RHino construction history doesnt work with all command. hopefully it will change in the next version.

working with NURBS will require alot of rebuilding and Re-constructing Srf so if you want to work with mesh paradigm I suggest you use T-spline. it works “similar” like poly modelling in which you can sculpt and make changes to the position of vertices, edges and faces.
but the workflow is kinda different. and its tools are still limited, only basic operation. not as powerful as other poly modeller software that I assume u are familiar with.

perhaps the next reply can give you better suggestion, but that is as far as I could think of.


(Pascal Golay) #3

Hi Steve -I would ExtractSrf all of the surfaces around the hole, UntrimBorder and then I intersect them to find new trimming curves that close the gap, at least possibly… feel free to post the object in a 3dm file and I’ll see if I can sort it out.



Thanks Runnie and Pascal
I really appreciate your help. I have saved the original so that I can go back to it and try out your ideas
but in the meantime, I did what all noobs will do in a fix- I cheated! Hahaha! It actually looks alright, but I am determined to use this program properly so I will definitely try what you have both suggested. Thank you so much for your help.



tossing some tips that I found useful when modelling in rhino=

  1. I highly recommend to keep all the original curve on a separate layer (normally I make a layer named “Curve_Ori” because building a surface has tolerance setting and when you fiddle with the setting at some point it can get slightly off from the original curve. so keeping the original curve is always handy.

2.also u can use the original curve as a guideline if you work with another software, to keep the model integrated with rhino.

3.another tips is to avoid so many unnecessary trim… as long as it is only 3 - 4 sided NURBS, no need to introduce trimming to the border edge of the Srf.

4.the last tips is by using Grasshopper in conjunction with your model. you can create your own definition library to support your modelling workflow.these add on for GH is useful if u want to hybrid mesh-Nurbs workflow = Weaverbird, Kangaroo and Mesh Tool

Happy modelling :smile: