Surfacing challenge - Round to rectangular surface transition - modelling advice


I wonder if any of you would have an idea how to model this sort of transition between round elliptical shape and rectangular. I have tried few different approaches to achieve smooth G2 continuity there without much luck.
I would appreciate an advice on modelling this asymmetrical shape.
Please see the attached files:

Below is a link to zipped Rhino5 file.

What do you wan the blend to look like?

Do you want both the edges and surfaces to blend smoothly or only the edges?

If the edges need to blend smoothly then how tight a curve do you want between side of the handle towards the center and the edge of the bowl? As the handle and bowl currently exist the edge of the transition would be very tightly curved to smoothly transition between the handle and bowl?

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Hi Gosia,

This is my quick test:

First I rebuilt the concave surface, it seems like you made it with tsplines. I made a similar surface, not exact but with squared layout, this may avoid the issues you could have with revolved surfaces.
Then trimmed the surface with a curva that gives enough space for the blend to flow naturally.
I hope this helps.


Rhino Surface Challenge_laborda.3dm (352.9 KB)

This is great Joaquin!
Thank you so much, it seems so obvious now…

May I ask how did you made the concave surface? Did you made it out of just planar surface, which you rebuilt, edited points, and trimmed to elliptical shape?

I guess that if I wanted the blended/middle/orange surface to flow back a bit, near the handle as per blue line on the picture below, I would need to either trim it off the current one or… it would be probably impossible task as @davidcockey suggested…


I made the concave surface extracting sections from your model, then extending and rebuilding them enough to create a network surface. And then yes, I used a plane to trim the area I didn’t need.
I rebuilt the surface result also before trimming.

I think you can force the blend a bit more than I did, but if you compress too much the control points in the beginning of the neck it will be better trimming. I think you need to test it a little.

Got it.
Thanks again Joaquín.

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