welding sparks particle rnd

Being used to both pFlow and Thinking Particles, Houdini's particle system seems a bit un-intuitive  at first. Took me a while to understand the Pop Replicate and that particle source threads actually are processed separately. Once I got my head wrapped around this, it wasn't that much different, after all. Perhaps a little bit messy, compared to the others. But at the same time way more flexible. Which I am starting to get used to with Houdini nowadays, haha.

I wanted to replicate a slow motion video I found on YouTube. You can see the reference video embedded in my video below. It's a large ember falling to the ground, once it hits it explodes into a massive burst. Most of it dies out quickly, some sparks lives longer, and quite a few bursts into even more particles both on collision and after just jumping around on the floor for a while. 
I thought this could be an interesting effect to tackle. It's not too complicated, once you understand the flow of the Houdini particle system. 
The first particle is spawned randomly from a grid plane in the air. It's given a pscale, and once it hits something I have three Pop Replicate threads spawning. All three reduces the original pscale. I haven't added randomness to this, but that'd be an easy task to do. 
The first burst is the massive, but short lived burst. Second is a a smaller burst, but with longer living particles. These also explode into multiple particles on collisions. The third replicate are the longest living particles. On birth I give them a random chance of exploding into yet another burst or particles once it hit a given age. On top of that all particles are gives some random velocity jittering when on the floor. Making them slightly bounce around. A separate particle thread controls the gravity, drag and other general forces. 

That is about it for this one.. All rendered with Redshift. Not quite happy with the motion blur on this, but I wasn't really focusing on a nice render this time. Just getting the effect right.

Houdini Particles RnD - Weld Sparks v03 from Trond Hille on Vimeo.