Model
Houdini has traditionally offered strong procedural modeling sometimes at the expense of its interactive workflow. With improvements made in Houdini 14 and now 15, modellers are now able to work intuitively in the viewport with the new tweak edit workflow, edge sliding, soft selection highlighting and new tools such as PolyBridge and PolyExpand 2D. For working with hi-res models, new retopology tools make it easy to build low-res geometry by drawing right on top of high-res geometry.

Render
Rendering in Houdini 15 is faster and richer with improvements to the Mantra renderer such as checkpointing and render view feedback. Shader building has been enhanced with a new shader library, a rebuilt Shader FX 2.0 menu, layered materials and a cartoon shader.
Houdini 15 also includes an implementation of Disney’s physically-based Principled Shader which is designed to provide artistic flexibility with a minimal set of controls. In addition, a library of royalty-free PBR Ready Textures will be available on sidefx.com for use with Houdini 15’s shader building tools.
Material stylesheets create a production-level workflow for creating and managing material overrides that work well with Alembic files and packed geometry. Easily set up random textures and variances in material settings to give a unique look to a collection of similar items such as crowd agents.

RenderMan 20
RenderMan 20 and RIS shading support is fully integrated into Houdini 15. RIS shaders are available in the RIS Shader Network SHOP and Houdini’s VOP context provides a native environment for building RIS shaders with OSL support.
“Pixar and Side Effects have worked together to create a first class experience for lighters,” says Chris Ford, Business Director - RenderMan, Pixar Animation Studios. “Houdini 15 offers interactive shader building tools which make it easy for artists to achieve the look they desire.”
Houdini 15 comes with a complete set of RenderMan BxDF, Pattern, and Integrator RIS shaders as well RIS light shaders and Camera, Light Probe, and Rolling Shutter RIS projection shaders. There is also a new RIS render node which allows the RIB and RIS render nodes to have cleaner interfaces specific to each mode.

Home Page - http://www.sidefx.com/