Forums Technical Discussion How to use Vellum to Sim Tree Curves?

How to use Vellum to Sim Tree Curves?

   1106   4   1
User Avatar
olivierth
Member
1177 posts
Joined: April 2017
Offline
 
Hi!

I exported curves from SpeedTree. I tried using vellum cloth and vellum Hair but both result in a tree that slowly crumbles to the groung. I've also increased the Bend and Strech stiffness to maximum but it still doesn't hold upright.

Any tips specific to vellum and curves for trees?

-Olivier
Edited by olivierth - Feb. 13, 2025 17:20:39

Attachments:
Houdini_Speedtree_Vellum_Curves_01.JPG (66.2 KB)

 Report
User Avatar
alexmajewski
Member
109 posts
Joined: Aug. 2017
Offline
 
Adding a thickness attribute which is thicker at the base and gets gradually thinner towards the branches, should dramatically improve a vellum skeleton's ability to stand upright. Same goes for density attribute or bend stiffness etc.
 Report
User Avatar
olivierth
Member
1177 posts
Joined: April 2017
Offline
 
I tried that. Bend stiffness at MAX, strech stiffness at Max and a big thickness. I tried High Mass and Low Mass, and high substeps. It always crumbles down to the ground.

I don't know what to do...

Attachments:
Houdini_Speedtree_Vellum_Curves_02.JPG (152.7 KB)
Houdini_Speedtree_Vellum_Curves_03.JPG (55.9 KB)

 Report
User Avatar
alexmajewski
Member
109 posts
Joined: Aug. 2017
Offline
 
Your thickness/mass needs to start thick and gradually get thinner. Check this [youtu.be].

Mesh density also plays a role in vellum simulations, as well as simulation substeps or constraint iterations (in the solver). The denser your mesh is, the less effective your bend/stretch stiffness constraints will be.
 Report
User Avatar
olivierth
Member
1177 posts
Joined: April 2017
Offline
 
Ah! This looks like the perfect tutorial! I'll test it out. Thanks!
 Report
  • Quick Links