Create pebble geometry



Hello everyone,
I’m sharing a task my friend has asked me about. Three plans are given and the expected result is a pebble-like object. My take was to intersect three extrusions but the result is pretty disappointing. Do you have any hints for a better approach?

We are both architects so our free-form modeling skills are quite limited. :slight_smile:

Thanks a bunch from us both!


(Pascal Golay) #2

Hi Jonas - a sort of standard way to get clean pebbly type shapes is to set up the shapes (blue in my file) as clean degree-three curves and arrange another set of curves (red) so that they fall on the control points of the initial curves and Loft with Style=Loose through the second set of curves and to a point (optionally) in the middle. If the lofted curves are all matching (e.g. edited copies of an original) then the resulting loose loft can be extremely simple and smooth.
I do this in quadrants, with History on the loft so that editing the red curves can modify the whole 8-piece pebble.
Pebbly_PG.3dm (195.9 KB)



The point part is very useful. Thanks.

(Pascal Golay) #4

Hi Sochin - the top curve, before the point, should be planar and the point also in that plane, for maximum smoothness. So if you move the point or the top curve, move them together (Assuming History, here) Grouping is handy.



Thank you, Pascal!
You’ve been extremely helpful like always, thanks to you I got the shape quite right. I used the trick with curves through control points and points as starting and finishing geometry. There is ± 100mm error, I believe it would disappear if I simply worked more precisely and assumed less to save time. :slight_smile:

(Pascal Golay) #6

Hi Jonish - the missing piece here is that the top & bottom curves need to be planar and the point at the singularity in plane with that curve - in your model the point is out of plane at the top and so you have a slight pointyness there. And the shape falls away from the blue curves in a side view…

Also, there’s no reason that the whole thing needs to be one surface - that angled accent might be a perfect place to blend between two surfaces, top and bottom, so that the curves from each can be different. BTW, I don’t know if the design is meant to by symmetrical but it is not, in Top.