Houdini (software)
Houdini is a 3D animation software application developed by Toronto-based SideFX, who adapted it from the PRISMS suite of procedural generation software tools.
The procedural tools are used to produce different effects such as complex reflections, animations and particles system. Some of its procedural features have been in existence since 1987.
Houdini is most commonly used for the creation of visual effects in film and television. It is used by major VFX companies such as Walt Disney Animation Studios, Pixar, DreamWorks Animation, Double Negative, ILM, MPC, Framestore, Sony Pictures Imageworks, Illumination Studios Paris, Scanline VFX, Method Studios and The Mill.
It has been used in many feature animation productions, including Disney's feature films Fantasia 2000, Frozen, Zootopia and Raya and the Last Dragon; the Blue Sky Studios film Rio, and DNA Productions' Ant Bully.
SideFX also publishes Houdini Apprentice, a limited version of the software that is free of charge for non-commercial use.
Release history
Features
Houdini covers all the major areas of 3D production, including these:- Modeling – All standard geometry entities including Polygons, NURBS/Bézier Curves/Patches & Trims, Metaballs
- Animation – Keyframed animation and raw channel manipulation, motion capture support
- Rigging - proprietary KineFX and APEX systems
- Particles
- Dynamics – Rigid Body Dynamics, Fluid Dynamics, Wire Dynamics, Cloth Simulation, Crowd simulation.
- Lighting – node-based shader authoring, lighting and re-lighting in an IPR viewer
- Rendering – Houdini ships with SideFX's rendering engines Mantra and Karma; Houdini Indie licence and up support 3rd party rendering engines, such as Renderman, Octane, Arnold, Redshift, V-ray, and Maxwell.
- Volumetrics – With its native CloudFx and PyroFx toolsets, Houdini can create clouds, smoke and fire simulations.
- Compositing – full compositor of floating-point deep images.
- Plugin Development – development libraries for user extensibility.
Tools
Operators
Houdini's procedural nature is found in its operators. Digital assets are generally constructed by connecting sequences of operators. This proceduralism has several advantages: it allows users to construct highly detailed geometric or organic objects in comparatively very few steps; it enables and encourages non-linear development; and new operators can be created in terms of existing operators, a flexible alternative to non-procedural scripting often relied on in other packages for customisation. Houdini uses this procedural generation in production of textures, shaders, particles, "channel data", rendering and compositing.Houdini's operator-based structure is divided into several main groups:
- OBJs – nodes that pass transform information
- SOPs – Surface Operators – for procedural modelling.
- POPs – Particle Operators – used to manipulate particles systems.
- CHOPs – Channel Operators – for procedural animation and audio manipulation.
- COPs – Composite Operators – used to perform compositing on footages.
- DOPs – Dynamic Operators – for dynamic simulations for fluids, cloth, rigid body interaction etc.
- SHOPs – Shading Operator – for representing a dozen or more different shading types for several different renderers.
- ROPs – render operators – for building networks to represent different render passes and render dependencies.
- VOPs – VEX operators – for building nodes of any of the above types using a highly optimized SIMD architecture.
- TOPs - Task Operators
- LOPs - Lighting Operators - for generating USD describing characters, props, lighting, and rendering.
Complex networks can be grouped into a single meta-operator node which behaves like a class definition, and can be instantiated in other networks like any compiled node. In this way users can create their own sophisticated tools without the need for programming. In this way Houdini can be regarded as a highly interactive visual programming toolkit which makes programming more accessible to artists.
Houdini's set of tools are mostly implemented as operators. This has led to a higher learning curve than other comparable tools. It is one thing to know what all the nodes do – but the key to success with Houdini is understanding how to represent a desired creative outcome as a network of nodes. Successful users are generally familiar with a large repertoire of networks which achieve standard creative outcomes. The overhead involved in acquiring this repertoire of algorithms is offset by the artistic and algorithmic flexibility afforded by access to lower level building blocks with which to configure shot element creation routines. In large productions, the development of a procedural network to solve a specific element creation challenge makes automation trivial. Many studios that use Houdini on large feature effects, and feature animation projects develop libraries of procedures that can be used to automate generation of many of the elements for that film with almost no artist interaction.
Also unique to Houdini is the range of I/O OPs available to animators, including MIDI devices, raw files or TCP connections, audio devices, mouse cursor position, and so on. Of particular note is Houdini's ability to work with audio, including sound and music synthesis and spatial 3D sound processing tools. These operators exist in the context called "CHOPs" for which Side Effects won a Technical Achievement Academy Award in 2002.
VEX is one of Houdini's internal languages. It is similar to the Renderman Shading Language. Using VEX a user can develop custom SOPs, POPs, shaders, etc. The current implementation of VEX utilizes SIMD-style processing.