VELLUM
- Sammy Lyu
- Sep 16
- 1 min read
Updated: Sep 17
This section focuses on the VELLUM solver for soft-body and clothes
As of writing, my Houdini version is 20.5.614
The foundation of the many variants of vellum solvers
“Vellum cloth” is the most basic type of the vellum solver, any other type of vellum solver is a variation of this one.
What is stiffness in vellum constraints
The stiffness value, which can be found under the "Stretch" tab in vellum constraints, dictates how much the solver will pull back on the geometry to its original shape when stretching happens. The more stiffness, the more the geometry wants to go back to its original shape.
What is damping ratio in vellum constraints
The damping ratio is the FORCE value at which to apply the stiffness value, so if the damping ratio is low, the force at which the solver starts applying the stiffness value will be lower when stretching happens.
What is rest length in vellum
The rest length dictates the CONSTRAINT DISTANCE, so the distance between two points of the vellum sim. If the rest length is higher, the distance between each constraint is higher and simulations like cloth are allowed to flow more freely.
VIDEO ON VELLUM BASICS
This video series below is very useful for new Vellum users. It explains well the attributes and functionality in the solver.