“Freeing the Raven”
Walt Disney Animation Studios training project
Creating during my time as a Walt Disney Animation Studios Trainee, this project was inspired by concept of being vulnerable and breaking down walls to reveal beauty inside. Created in Houdini and rendered with Hyperion, I got to play with many different solvers to create the layers of effects such as destruction, dust, debris, cloth, caustics, and ethereal smoke and particles. I also created a custom cracking rig to enable me to draw and custom animate cracks along the statue.
Responsible for: All aspects aside from environment and statue.
Software: Houdini, Hyperion, Harmony, and Nuke.
Inky Smoke: I wanted the spirit smoke flying into the raven statue to feel magical, and remembered seeing ink in water once and being mesmerized by the fluid, swirling motion. To replicate that feeling, I created a custom velocity field with multiple sizes of swirls that pull the smoke into spirals as it’s released.
Art-directable cracks: I wanted control over where the cracks were, and how they animated, so using an HDA I built, I was able to hand draw cracks on the geometry, and animate them using a VEX wrangle that relied on a ramp and custom start and end frames for each crack.
Fracturing: To setup the asset to be able to procedurally crack and then simulate as RBDs I fractured in three layers, a base fracture for the large chunks, a boolean fracture cutting pieces where the hand drawn cracks were, and a detail fracture which had a bias closer to the crack so that pieces were broken into smaller and smaller chunks as they got closer to the cracks.
Procedural cracking: Based on when the drawn cracks animate on, I procedurally rotated each piece using a matrix, and pushed it in along the normal to create the cracking look. The downfall to this method is piece intersection, which, after trial and error, I ended up being able to resolve by calculating the vector from each piece to the nearest point on the crack curves, which allowed me to translate each piece actually outward with a controllable bias the closer the piece was to the crack. This eliminated any piece intersection and also resulted in a more realistic read, since when stone breaks, the pressure displaces more than just the pieces directly beside the crack
RBDs: Since the statue was exploding from internal pressure, I needed to vary the motion to create a readable and appealing effect. Varying the drag per piece helped, as well as sourcing the outward forces from the cracks. The constraint strength was weaker closer to the crack and stronger farther away so that some chunks could remain clustered when not under as much presssure.
Rays of light: I could have done the light rays in nuke, but I wanted to be able to customize and control their growth, motion, and direction. I ended up creating lines that were rasterized into volumes, and controlled by custom length, growth, color, and direction attributes that could be run through noises to add variety.
Spirit: The resolve of this shot is that the statue breaks to reveal a beautiful spirit that was confined inside. I wanted to create a wing-like butterfly shape, since butterflies experience evolution from caterpillars to their winged forms, and that supported narrative. I stumbled upon some majestic reference of artists using silk and thin fabrics to create beautiful patterns in the air with fans blowing it upward and around. This was perfect for the look I was going for, so I used vellum with custom repellant forces to unfold the fabric, and then turbulent wind blowing it upward. To complete the spirit look, I ran multiple pyro and pop simulations swirling around the cloth and faded the edges out using an alpha mask to remove any hard edges.
Caustics: I’ve always been mesmerized by the patterns that light can create when paired with the right refractive surface, so caustics seemed like the perfect addition. I looked into different ways of creating this, and ended up going with a point-cloud based approach that reacted to the motion of the spirit. This let me visualize the caustics easily and created a final look I was happy with!