Hydra Powered Viewport
Katana now features a new, modern viewport powered by Pixar's USD Hydra technology. Designed to render massively complex scenes, the Hydra viewport is a perfect addition to Katana’s Viewer API. Now artists can load huge scenes and view larger portions of their work with buttery-smooth interaction. To compliment this new level of user experience, there’s a set of artist-friendly transform handles, a rich API for creating custom object drawing and manipulators. This new viewport is the game changer all Katana artists have been waiting to have at their fingertips.

Performance Improvements
No matter what program you use, how much work you get done always comes down to performance. Katana is the same and the team have done a lot of work since Katana 2.6. While the new viewport is 7x to 10x faster, Katana 3.0 itself now starts up and loads files 1.5x faster than previous versions. General performance has also been improved by strategic changes to key areas like CEL, OpScript, and Alembic processing.

Improved UI
As a compliment to the new viewport and improved performance, we’ve updated the design of the overall UI, added new transform tools, and made information easier to process, so artists can now get more information from Katana at a glance. All part of our larger plan to merge artist driven workflow and UX with Katana’s power and technical foundation.

Integrated Rendering
Katana 3.0 would be half a solution without a rendering plugin, so Katana 3.0 ships with the NSI powered 3Delight rendering plugin giving users best-in-class production live rendering, free of charge for interactive renders. Fast, powerful, clean rendering and super easy-to-use, this renderer has lots to offer everyone. The 3Delight plugin is the first to tap the full potential of Katana’s rendering APIs.

What's New in Katana 3.1
https://learn.foundry.com/katana/Content/release_notes/whats_new_3.1.html