An Arnold procedural plugin

Harold is an Arnold procedural that inputs Houdini Digital Assets (HDA), along with simulation parameters, and renders the assets directly. Harold also facilitates cloud rendering.

We built Harold to speed up and to simplify fur simulation rendering while working on Paddington 2, and the plugin is now a standard tool used by our artists for fur rendering. It took our team roughly a month to make the base, and we continue to evolve the tool according to production feedback. As well as rendering fur, Harold can now also handle other kinds of geometries, and, thus, other types of simulations.

This plugin helps our artists avoid having to export a full file that contains the result of a simulation, such as fur, and then having to render it. Such exported files take time to produce, take up significant disk space, and need to be produced for each frame. With Harold, artists don’t need to go through this step.

Harold also enables lighters to keep control over the simulation before rendering it. Without Harold, files passed to lighters have baked simulations, so any change in simulation parameters requires a new export of all files.