Is it possible to create a surface on a closed curve shape that are not on the same plane (but not a 3d object)?

Hi GuyLuke, you can cut the close curve in two curves, then selct the curves and "loft".

Hi GuyLuke, usually it is best to create a surface like this using 2D profile curves from the side and top views instead. You want to extrude one of the 2D profiles to make a base extended sheet and then trim that using the other profile curve.

So then the 3D curve is generated at the end of that rather than starting with the 3D curve initially.

- Michael

So the 2D profile curves would be like this.

One 2D profile in the Top view like this:



The other 2D profile in the Front view like this:



Here both shown in the 3D view:



Extrude one of the 2D profile curves out to make a base sheet:



Trim using the other 2d profile:



This generates the best quality surface where the underlying surface is very regular and has no pinching.



So the nonplanar 3D curve is generated by a trim or boolean instead of trying to start with it.

It can usually save some steps and be more convenient to work with solids - extrude the Top profile to make a solid cyllinder and then cut the cylinder with the side profile as the cutting object. That will also generate a trimmed extrusion for this surface but it will already be all connected up to surrounding surfaces instead of just being a single isolated surface.

- Michael

Thank you for the solutions. Just wondering why the planar command can't be made to render nonplanar surfaces like this from a closed curve? I'm also trying to figure out how to cut the 3d closed curve into equal halves, I would have thought a boolean merge with a straight line through the middle would have worked but it doesn't.

Hi GuyLuke,

re:
> Just wondering why the planar command can't be made to render 3d surfaces like this from a closed curve?

The planar command only knows how to build a planar surface which is not what you have here.

I would at some point like to make a method that would automatically reverse engineer the 2D profiles from a 3D curve like this. That will be fairly difficult to make, in the meantime it's better to use 2 2D profile curves to generate it by extrusion and cutting as I showed above.

Usually it is best to work primarily with 2D curves and generate 3D curves as the result of intersections instead of trying to generate a surface from a 3D curve.


> I'm also trying to figure out how to cut the 3d closed curve into equal halves, I would have thought a boolean
> merge with a straight line through the middle would have worked but it doesn't.

Can you please post the .3dm file with the line through the middle that isn't working for you?

Usually Edit > Trim is the thing to use to cut a curve.

- Michael

Thanks Michael, it's OK I just figured it out using trim.