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Simulating the Perfect Groom for a Bovine Biker | Untold Studios | FMX HIVE 2023
Untold Studios FX Supervisor describes rebuilding their internal fur workflow in Houdini to deliver the CGI highland cow groom for Virgin Media's Highland Rider commercial.
Abstract
Georges Kyparissous, FX Supervisor at Untold Studios, describes the non-destructive Houdini fur workflow built for Virgin Media's Highland Rider commercial featuring a photoreal Highland cow on a motorbike. The setup splits the incoming groom into long hairs to be simulated and short hairs to be deformed, sanitizes attributes via an OTL, generates lighter resampled guides from the longest hair in each clump, and stores per-curve offset vectors to map the full groom to its guides. Simulation uses Vellum hair with the animation localized at the origin and a generated POP wind field standing in for character motion, casting to 64-bit to avoid floating-point artifacts, plus CurveU-driven angular attributes for matting and root differentiation. A minimal-input deformer reapplies the groom using parametric UVs and transform-matrix differences with delta mush smoothing, while muscle, skin sliding, and rendering are handled in Houdini with Arnold, and caches are written to delay-loaded split Alembic for efficiency.
How to read this
- Category
- Production talk: a fur grooming and simulation workflow breakdown
- Contributions
- Demonstrates a non-destructive Houdini fur workflow that splits the groom into simulated long hairs and deformed short hairs
- Shows guide generation, per-curve offset vectors, OTL attribute sanitization, and Vellum hair simulated at the origin with a POP wind field standing in for character motion
- Demonstrates a minimal-input deformer reapplying the groom via parametric UVs and transform-matrix differences with delta mush, casting to 64-bit to avoid floating-point artifacts
- Context
- Relates to strand-based grooming and Vellum/Houdini fur pipelines, applied to a photoreal Highland cow for Virgin Media's Highland Rider commercial.
- Correctness
- Studio practice, not peer-reviewed; results are production-proven for one commercial and the choices are pragmatic rather than generally validated.
- Clarity
- Accessible to FX artists; a single viewing conveys the pipeline, with Houdini fluency helping for the node-level specifics.
- How to read it
- Watch for the reusable tricks (long/short split, guide offsets, sim-at-origin with wind, 64-bit casting, delta mush deform); no second pass needed beyond noting techniques to adapt.
Related work
Keywords
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