Basketball Simulation in Houdini (Research Project)

This month in Software Technology class, we were asked to do a research project on making a basketball go through a hoop. (All the models would be made by students as well as figuring out how to make the simulation work.)

I modeled the assets (the basketball rim and the basketball) in maya and imported them as OBJs into Houdini.

When thinking about how to carry this out the first thing that came to mind was to figure out what force would send the basketball through the hoop. The first thing that came to mind was to use some sort of lever system to drive the ball's take-off. so, google!

I found a few interesting tutorials, but I found more of what I needed when looking at Introductory videos to Houdini, most people were demoing the software with the demonstrations that I was looking for.

I settled with a catapult system, creating a plank, a RBD ground plane, a tube and a box object. With my modeled assets in the scene, I made the tube a Static Object, and every other thing was a Rigid Body so it could move.

My ball did not go through the hoop. The ball kept bouncing off the edge of the rim in a really odd, unrealistic fashion (without contact). It did not actually touch the rim and bounce off as it would in real life.

The only flags I could think of was that my projection was not properly set up. I messed a lot with with the weight and height of the box that drove the simulation, but I quickly came to terms with the fact that that was not the issue.


It turns out that the right way to look was in the AutoDop Network (shown below), as per the directions of the Instructor, and I was to change my rim's RBD solver type. A quick switch in the Bullet Data from Convex Hull to Concave got the ball and rim interacting properly.

My AutoDop Network