Pinocchio

One of Us, 2019

Woodpeckers

Groom, CFX, Lighting

I had 20 days to develop a feather groom system, followed by a few weeks to tweak the look of the feathers between other tasks. The result: the ability to have several birds in the scene rendering full grooms (no texture cards), complete with AOVs enabling control of multiple elements in the groom.

Being told I had just a month to groom a bird took me by surprise; I subsequently spoke to my previous groom lead, who advised 3 months for such a feat. So, how could this be done in such little time?

In short: Python, Vex, Arnold, Houdini.

(The fantastic four!)

Method

Create multiple shapes/sizes of the required feathers: Remix, rectrix, covert, contour, bristles, filoplumes, semiplumes. These contain all attributes, which can also be passed into the aovs.
Using python, create a directory structure to cache the feathers into, which makes it easy to grab the feathers in whichever required size in the groom.
E.g. Feathers/<featherType>/<sizeVariant>/<dataType:ass|bgeo.sc>/<fileCache>
In the scene, they're viewed as bgeo instances, and the amazing Arnold's .ass format is used for the final render.
Groom guides as normal (only 2 points/prim are needed) and paint masks such as 'mask_contour', 'mask_semiplume'.
In vex, use the mask to set the chance of a hair being of that feather type. I also used the feather hair's perimeter to create a 'bias', so the sizeVariant could be allocated correctly. E.g. If prim01 has a perimeter of 0.1 and prim02 has a perimeter of 10, and they're both feather type 'contour', their sizes are fit into a 0-1 bias. This bias is used in a python wrangle to select either feather size var A, B, C.
Create orients using the skin's normal, the vector from vtx0-vtx1 of each prim hair, and the cross product of these.
After wrangling, you're left with root hair points with an orient, instancefile and pscale, which are all you need to render the feathers with Arnold.

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Sources I referred to:

Featherbase for feather reference: https://www.featherbase.info/en/species/
Matt Estela's website to learn about maketransform and orients: http://www.tokeru.com/cgwiki/index.php?title=JoyOfVex17
SolidAngle Arnold docs
SideFX Houdini docs
Odforce and SideFX forums (Special thanks to users of the names Atom, Matt, Thomask)

Donkey

Groom, CFX

With similarly a short amount of time, the donkey groom was featured in a mid-range underwater shot and a far-range shot. I simulated the tail and mane, and was able to easily have a stable CFX cache for the 1000+ frame shot thanks to Houdini's Vellum. For the rope, I generated it procedurally along the simulated curve by reusing a hda I'd made in the past, which I frequently use in grooms when creating string.

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Special thanks

To everyone who I'd had the pleasure to work with on Pinocchio. From working closely with the riggers, animators and compositors with the woodpeckers, to the wonderful producers, my supervisors and everyone I'd been lucky enough to sit near and exchange words to - I made some long-lasting friendships. We now each get a little giddy when we see another 'ex-pinocchio' colleague is on our shows!