Arnold for Maya (or MtoA) provides a bridge to the Arnold renderer from within Maya’s standard interface. MtoA is now shipping with the Arnold 5.0 core.
Seamless integration with Maya shapes, cameras, lights and shaders.
Image Based Lighting support, including a state of the art physical sky.
Interactive rendering (IPR) allows parameter changes to be rapidly previewed without interrupting your work.
Support for volume rendering with Maya Fluids.
Support for Maya Hair and nHair.
Particles and nParticles support, including particle instancer.
Defer the creation of geometry at render time with the Stand-in placeholder nodes.
Productivity boost: override sets, holdout mattes, shadow catcher, passes, UDIM style textures, and arbitrary primvar data.
Extensible through plug-ins (Golaem, FumeFX for Maya, Yeti, Shave & Haircut).
Texturable geometric lights.
Rendering of curves.
Faster GPU cache pre-population.
Arnold RenderView now displays properly with High DPI monitors.
Improvements in the Operators UI for Standins / Alembic.
Added option in ARV to clear the whole arnold session when IPR is stopped. When IPR is restarted, the whole scene is converted from scratch (as with Update Full Scene).
aiUserDataColor now supports RGBA data, with an alpha channel.
All matrix parameters in shaders can now be exported in motion blur
Added more options for exported node names, to control the namespacing as well as the hierarchy separator
MaterialX exporter allows to export hierarchy with slash separators, in order to work with exported alembic files
Maya Playblasts can be generated from the Arnold Viewport.
Fixed 3.2.0 regressions in Maya Ramp shading
Fixed 3.2.0 regressions in Projection shader results
Fixed 3.2.0 regression in Image plane when displayMode=None
Fixed vector displacement order with tangent maps