How to Demolish a Building: The Power of FX in Houdini
Hadrien Palanca, a French Freelance Motion Designer and FX Artist, used his knowledge of 3D to create a robot collision, as well as destroy a giant tower in Houdini. From fracture points to dust effects, read on to see how he did it.
Introduction
Hi, my name is Hadrien Palanca, I am a freelance motion designer and FX artist based in France. I do 3D work for commercials, TV, live events, music videos, etc. I was introduced to After Effect and Cinema 4D when I was in college, mostly completing projects for extracurriculars. I immediately enjoyed it and decided to make a living of it.
I was curious about using Houdini but never dared to take the leap until I saw the VFX breakdown of the movie Attraction from Main Road Post. That was it! I decided to take a leap and learn Houdini whatever it’d cost. And it cost me A LOT of time! But it was completely worth it.
I think by looking at both of my results you can see the progression, especially in the smoke simulation. Those two courses really helped me to learn a lot within Houdini.
Impressive Destructions in Houdini
You want to have a clear idea of what your destruction will look like because you will fracture your geometry according to that mental image. There’s no point in fracturing a part of a building which is not supposed to break, right? For this, your geo must be as clean as possible (no intersecting geo or unfolding geo). After that, you fracture it and get it ready for simulation.
Then, you stack multiple sims on top of each other.
The point is not really to build a «physically correct» destruction. Houdini constraints are not aware of weight, for example, a thin paper-like piece of concrete could literally handle the weight of a whole building. The point is rather to build destruction which looks plausible to you and is as pleasing to the eye as possible.
Setting Destructibles
There are multiple technologies that allow you to build destructible structures and simulate fracturing. Here, I used the bullet physics engine. It was initially designed for games and is now widely used in VFX for handling large numbers of rigid body pieces. You work with physics by giving attributes to pieces that the solver will then understand: speedmax, spinmax, gravity, all sort of information that you give the solver to have the desired look. There are no good or bad settings, there is only what’s working for your project or not working.
Dust Effect
The dust effect is not that complicated, it is a combination of 3 simulations: particles sim for the dust with grains, smoke sim and a rigid body sim for rocks.
A growing circle around the character (in the Tower Destruction) scatters points on it and according to the center emits more or less smoke/density. Everything is driven by this smoke sim.
Find surprising and effective other uses for dust in CGMA course Texturing and Shading for Games.
Testing Sims
Usually, you want to iterate quite a lot and tweak settings, so it’s necessary to start with fewer pieces, lower collision resolution, and fewer sub-steps so you can get quick feedback about what values work best. And then, when you are happy with the behavior of your pieces, you crank everything up.
Advice for a beginner: I would say that no shot will ever be perfect, so the most important thing is to try and get better every time.
Hadrien Palanca
Advice for a beginner: I would say that no shot will ever be perfect so the most important thing is to try and get better every time. Obviously, if you are a beginner, it will not be impressive at first but try, fail, repeat… until your result gets really good.
If you're starting out with Houdini, check out CGMA course Fundamentals of Houdini for 3D Artists.
Challenges
For me, the most challenging part of Manuel’s course was to combine my daily freelance work with weekly assignments that you have to do. It was a lot of work, which was not always easy to manage with high demanding projects.
As for the shot itself, I would say the biggest challenge was the clustered fire sim for torches inside the tower. I had to do multiple clusters for every torch so it was challenging to understand how things work and make the solver understand how to resize dynamically the simulated area for each torch. I ended up with a real mess in my network and some torches actually aren’t very well simulated but, overall, you don’t really notice that.
Recommendations for Learners
When it comes to giving advice to the beginners, I personally would not recommend starting learning 3D in Houdini. It’d be better to start first with something easier to have a solid foundation of the principles in 3D and then move on to Houdini.
I started with Cinema 4D and if I had to understand both how 3D works (textures, UV, normals…) and how Houdini itself works, I don’t know if I could have made it.
If you already know 3D, then start with a general introduction which explains what every button does and how Houdini works. That’s not as exciting as a fancy tutorial on building destruction, but you if you have a more solid understanding of Houdini you will be able to use it in every situation. That is not always the case for a tutorial on a specific effect. Once you get a good grasp on Houdini, I would then recommend Applied Houdini from Steven Knipping. For me, this is the where you can get the most valuable information out of your money and believe me, I have bought A LOT of Houdini courses!
Instructor Keith Kamholz provides an overview of his course Mastering Destruction in Houdini.
Feedback
- I am kind of extreme when doing things. I bought a lot of Houdini courses available on the internet (Rebelway, Applied Houdini, Renascence Program, Pluralsight, and more) and studied them as much as I could (at a given point I was studying Houdini 14 hour a day). I was willing to know everything I could.
- At CGMA, I took the 2 Houdini courses for destruction – one with Keith Kamholz, Mastering Destruction in Houdini, and the other with Manuel Tausch, Intro to FX Using Houdini. I am really happy to have taken them in this order because I was still new to Houdini when I took the first one, and Manuel’s course is really tough!
- CGMA courses were both (Manuel’s and Keith’s) really helpful and full of great production-proven techniques. This was gold! Especially for me because I don’t work in a studio environment full of Houdini killer artists ready to share tips and tricks with you.
- I have learned so much within those two courses that it is hard to point out a particular thing I have learned. But I would definitely recommend both courses at CGMA!
RELATED LINKS
Instructor Keith Kamholz provides an overview of his course Mastering Destruction in Houdini.
Find surprising and effective other uses for dust in CGMA course Texturing and Shading for Games.
If you're starting out with Houdini, check out CGMA course Fundamentals of Houdini for 3D Artists.
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