Loft in Grasshopper works different to the loft in Rhino?

Grasshopper
#1

Hi there,

I’m pretty new to Grasshopper but managed load a Scan of a foot into Grasshopper, then divide it into points which i turn into Nurbs that should be loftet.

Loft_Grasshopper1

Up to the Nurbs everything works fine

Splines_Rhino
Splines_Rhino.JPG706×735 29.7 KB

But the loft has kind of a rotation in it as you can see at the pictures!
loftgrasshopper_unbaked
loftgrasshopper_unbaked.JPG526×649 13.7 KB

As i baked the loft i saw that the line in the loft (I am not really sure what it means, probably starting points of the curves?) twists a bit as it goes down to the heel of the foot
Loft_Grasshopper
Or at least it has not the same line as the loft of rhino itself (where also the rotation and also the resulting wrinkle does not appear) Loft_Rhino

My question now is:

  • Is there a possibility to loft in grasshopper the same way Rhino does?

  • If not, is there a way to edit the loft of grasshopper such that the rotation does not happen anymore?

Thank you for your help!
LL

#2

Can you upload the curves (either as a 3dm file or internalised in a GH Curve parameter)?

It could be a problem with Seam Adjustment. For closed curves the Loft command may perform some additional steps to try and align them more neatly, but it’s hard to know without seeing the difference myself.

#3

Yes sure
Splines_foot.3dm (65.4 KB)

#4

You can see that the curve seams are all over the place (I used the _CrvStart command):

foot
foot.png555×652 9.83 KB

And the _Loft command does indeed pick smooth seam points and allows you to modify them:

loftseams
loftseams.png391×667 14.3 KB

Grasshopper does have a component for adjusting curve seams, but figuring out the exact seam parameters can be tricky. I used a Curve CP component, but it’s still wobbly:

seamadjust
seamadjust.png802×1051 289 KB

loftwithseam.gh (7.2 KB)

1 Like
#5

Here’s a more involved solution for creating smooth seams. First I do what I did already, but then instead of using the points immediately, I create a polyline through them, smooth the living daylights out of that polyline, then use this smooth polyline to find new seam points.

smoothseam.gh (11.2 KB)

smoothseam
smoothseam.jpg1509×1304 326 KB

3 Likes
#6

Nice thank you very much it works now!

#7

The AI-Engineered, 3-D Printed Cast That Won’t Drive You Crazy

not an ad… Arthur Harsuvanakit, a designer for Autodesk

171129-AI_cast-tease_mu3wu6
171129-AI_cast-tease_mu3wu6.jpg1480×833 108 KB

#9

Show us your code with internalized geometry?