What Project Violet is

Project Violet is a tutorial series made in Houdini 21, of the “Intermediate” Level, by Sam Taylor. The series shows new character features and workflows in Houdini 21 while combining the production readiness of Epic’s MetaHuman system with Houdini rigging and simulation workflows to build an approachable full human workflow.

That matters because it narrows the promise. This is not a inspiration reel, but a character pipeline exercise, with the character coming from MetaHuman and the heavy lifting happening in Houdini. If your day job sits anywhere near character setup, deformation, or character-adjacent sims, Project Violet wants to show you how to reuse, get a decent iteration speed, and getting a believable human through a procedural toolset without constantly falling back to manual rig babysitting.

The pipeline pitch: MetaHuman base, Houdini control

The main idea: take MetaHuman as the starting point and use Houdini for rigging and simulation versatility. It calls MetaHuman “production-ready” (we could discuss that, yet, the character is still in intensive care), and it presents that as the baseline you inherit rather than something you rebuild. Everything after that becomes a question of how far you can push Houdini’s character toolset once you stop spending weeks on initial asset authoring.

Houdini 21: Like good wine (Part1, VFX & Geo)

A separate SideFX-side (hehehe) for Project Violet describes it as an evolution of an earlier character-centric project, and it wants to focus on greater realism and expanded capability of the character, to showcase Houdini rigging and animation capabilities updated for new features and efficiencies in Houdini 21, and demonstrate a character pipeline that emphasises proceduralism while using MetaHumans as a base for the workflow.

That language is still a pitch, but it dosn’t widen the scope. The project is about a workflow, not a single solver trick. It aims to demonstrate procedural character work in Houdini 21 with a MetaHuman starting point.

One practical caveat: none of these claims your exact studio constraints, problems and idiosyncrasies of the colleagues get solved. Your skeleton naming rules, mesh structure, and export requirements still exist. Project Violet shows a route, not a universal treaty.

Houdini character tooling under the hood: APEX Autorig Builder

If Project Violet is the show, the APEX Autorig Builder is one of the stagehands. The APEX Autorig Builder SOP is a tool to interactively apply and configure pre-built and custom rig components through the viewport, which aims to make character setup more intuitive and lets you quickly build a complete rig.

SideFX draws a line between the APEX Autorig Builder SOP and the APEX Autorig Component SOP. The Builder can add multiple rig components, supports interactive viewport rigging, and allows modifying a limited set of component parameters in the viewport. The Component SOP adds one rig component at a time, can be used to create custom components, and exposes the full set of parameters in the parameter editor.

Back to Project Violet, because it glues the workflow in Houdini’s modular rig component approach rather than a one-off rig graph built for a single hero asset. Even if you do not adopt the exact tutorial approach, those constraints and mechanics tell you what Houdini 21 expects when you try to scale character setup.

Unreal and MetaHuman side of the bridge

Project Violet ties into Unreal. Epic’s MetaHuman are tools to assemble a MetaHuman character or create MetaHuman-compatible grooms in SideFX Houdini.

That tells you two things. First, the pipeline is not only about ex/im-porting Alembic and hoping for the best. It involves a toolset that lives in the Unreal ecosystem but targets Houdini as the working environment for certain tasks. Second, the workflow depends on version compatibility and installation details that can change across engine builds, pipeline images, and studio IT lockdowns.

This is where the series may appeal to teams that want to get to motion and deformation problems quickly, or to studios that already standardised on MetaHuman for certain classes of characters and now want deeper procedural control on top.

Either way, run a controlled wokrflow test before you bet a show schedule on it.

https://www.sidefx.com/tutorials/project-violet/

https://www.sidefx.com/docs/houdini/character/kinefx/autorigbuilder.html

https://dev.epicgames.com/documentation/metahuman/metahuman-for-houdini

The post Project Violet links Houdini and MetaHuman first appeared on DIGITAL PRODUCTION and was written by Bela Beier.

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For those who won’t sit through a 2.5-hour livestream

SideFX used its Vancouver keynote to preview Houdini 21, a release positioned as its most production-ready to date. The actual launch is planned for the end of the month. The presentation was packed with feature demos, technical deep-dives, and just enough dry humour to keep the audience from slipping into a procedural trance. If you’d rather not commit an afternoon to watching the full video, here’s the condensed version. And as always with software development: while this looks great, many details can still shift before release.

Finishing what they started

Rather than debuting new frameworks, SideFX’s development mandate was to complete and stabilise existing toolsets, improve robustness, and raise ease of use. This approach has resulted in the largest number of features ever shipped in a Houdini version.

Several frameworks move from beta to production: Apex-driven rigging, animation and motion mixing in KinFX; the Copernicus framework for 2D/3D workflows; and the Vulkan-based viewport, now replacing OpenGL entirely. Established toolsets also received significant functional and usability upgrades, including Solaris, Karma XPU, and the MPM dynamics solver. Two older but widely used systems have been rebuilt: terrain erosion, and the muscle system, both delivering more physically accurate results and easier setup.

Machine learning with restraint

SideFX reiterated its measured approach to machine learning, aiming to augment procedural workflows without removing artistic control. In Houdini 21, ML features move from R&D to deployable tools, with applications such as corrective joint workflows and ML-trained deformers.

Animation and motion mixing upgrades

Houdini 21 introduces multiple animation updates: Ragdoll Tether constraints, Scene Animate Prop for destruction effects, Animation Catalog for reusable poses and clips, improved viewport controls, auto-offset constraint controls, and a Motion Mixer for non-linear blending without breaking IK.

KinFX rigging developments

KinFX gains an interactive drag-and-drop interface for rig components while retaining procedural depth. Hierarchy analysis supports retargeting to characters with different proportions. Houdini 21 also ships with Otto, a fully rigged biped asset with production-grade IK/FK blending and anatomical skeleton setups.

Integration with Epic Metahuman

In collaboration with Epic Games, SideFX has developed a forthcoming plugin for importing Metahuman characters into Houdini for further animation, simulation, lighting, and rendering.

CFX: Otus soft tissue solver and beyond

The GPU-accelerated Otus soft tissue solver delivers FEM-like quality at higher speed, supporting combined muscle and tissue simulation, fascia generation, robust collision handling, and built-in skin sliding. A muscle transfer toolkit allows reuse of Otto’s setup on new characters, even non-human.

ML-trained deformers and sculpt-over-time

ML-trained deformers replicate full CFX simulations in real time, significantly improving over bone deforms. Sculpt-over-time enables shot-specific fixes within the motion mixer’s non-linear system.

Modelling, UV, and baking enhancements

Quad Remesh improvements, Unsubdivide SOP, UV Flatten from Points, and rebuilt baking workflows (for Karma and COPs) now share a GPU raytracing backend for speed and consistency.

Test before deployment

SideFX states Houdini 21 tools are designed for production use, but as with any pipeline change, artists should validate new workflows in their own environments before committing to shows. And until the final build ships, some of these features may still shift — it is software, after all.

The post Houdini 21: SideFX pushes for production readiness across the CG pipeline first appeared on DIGITAL PRODUCTION and was written by Bela Beier.