The Foundry’s KATANA 2 Lights the Way to VFX Pipeline Integration

The Foundry’s KATANA team said the software is now designed to be more open and collaborative so that less time needs to be spent computing, and more time can be devoted to caching and generating scene data – such as lights, cameras and object positions - on multiple threads during rendering.

KATANA 2 now has a moreresponsive user interface, and a new public API -Op API, its new core software engine. Ops, or operators, are the core processing unit of theGeolib3library for efficiently loading and processing the scene graph’s locations and attributes. Ops can both generate new scene graph locations and process incoming attributes – replacing the Scene Graph Generators and Attribute Modifiers that previous versions of KATANA used.

TheOp APIallows users to write plug-ins to create and modify scene data and, in practice, no distinction is made between scene graph generation and modification. The code you need to write for the Op API is also much simpler than before because it is event-driven and works with the new engine’s asynchronous processing. With this API, artists can createclients- using either C++ or Python - that can ask for scene graph data from any Op at any location and receive an event when the data is ready, or persistently observe a location and receive an event when data changes.

With the new Lua-basedOpScript node, artists can manipulate data from within the KATANA UI. This change was made to give higher performance than the previous Python-based script node and supports multi-threading. With access to the complete new Op C++ API, artists can use OpScript to perform complex operations that manipulate the scene graph hierarchy. KATANA 2’s performance has also been increased when working with renderers that support multi-threaded geometry creation, including RenderMan and Arnold.

Another scripting update is support formaths operations. For example, artists can write scripts for KATANA 2 to carry out processing of geometry and transforms that includes matrix and vector mathematical operations, due to access to Industrial Light & Magic’s industry-standardImath libraryto use in OpScripts. 

A major change to KATANA 2 isGraph State Variables, used to increase efficiency and reduce the need for project segmentation. GSVs let artists set nodes to change their behaviour based on the context in which the scene is being evaluated at any given time – that is, depending on which shot within a sequence, or which pass within a shot, is being rendered.

In other words, you can now use Graph State Variables to control which nodes in the node graph contribute to scene graph processing, based on the Variables’ values. Their key concept is that the Variables can be set either at a global, whole-project level, such as a variable for the shot number in a sequence that is being worked on, or at a local level using VariableSet nodes, for example, for a variable that indicates which render pass is being evaluated.

Graph State Variables have been designed to make it easier to set up a single KATANA project to control the lighting for a whole sequence, for instance, or to perform edits and overrides only active in the node graph, depending on which output is currently being rendered. You can define your own variables, which can then be used in many different ways.
 
KATANA 2 has been improved to make working with large numbers of lights faster and easier by developing a new, more efficientGaffer Three Super Tool. This tool is used to edit existing lights as well as create new ones, define lights at the sequence level and modify them on a per-shot basis. Artists can also create custom packages to specify the types of lights or light-like objects that can be created and edited.

KATANA 2 has faster, more stable and easier to useLive Rendering, for both lighting and look development. Users can restrict and modify updates to specific parts of the scene graph for better interactivity, even while the Live Render is in progress. Artists can modify Interactive Render Filters in the middle of a Live Render, as well as set custom options for each renderer directly in the Node Graph.

Atechnical guideto KATANA 2, including the Op API, GeoLib3 and Graph State Variables, for pipeline developers can be foundhere.  www.thefoundry.co.uk