In this Houdini tutorial, we'll examine multiple methods for accomplishing high resolution object simulation in Houdini using lower resolution proxy objects. In practice, when designing effects for motion pictures, we're often given very hi-res geometry (cars, rocks, etc) and are expected to simulate them in high quantities, which can be prohibitively slow using the actual objects. By making lower resolution proxies to use as RBD objects (or from a particle sim-and-replace) and replacing them post-simulation, the process can be greatly sped up. Different methods can be utilized for simulating multiple objects, packed objects, and varying topologies (for example, we wouldn't want every rock to be identical, or a parking lot full of many copies of the exact same car). At many studios, custom software is used due to these problems. Specifically, we'll do two test cases to demonstrate all the details and trade-offs of using the various methods. In the first test case we'll make a volcano spewing out hi-res rocks and finally we'll create a 'Carnado' (a tornado hitting a parking lot of cars, throwing hi-res car models all over the place, simulated with low-res proxy cars). By the end of this Houdini training you'll have a firm grip on how to use Houdini 14 to overcome these hurdles and simulate with low res geometry but use high res geometry in the final result. Software required: Houdini 14.
Jeff Wolverton has been working on visual effects for major motion pictures for over 15 years, having created signature effects for Sony Pictures Imageworks, Digital Domain, Rythym & Hues, Framestore, MPC, Disney, and Dreamworks.