MtoA 2.0 is based on Arnold 5. This version contains major changes. It is not backwards compatible with older scenes. An Arnold 5 FAQ is available here.
- aiStandardSurface : a new surface shader was added, with intuitive and energy conserving parameters, a secondary specular coat with separate normal, metallic Fresnel, thin surface support, per-light AOVs, and more. This shader supersedes the old aiStandard shader, which is now deprecated.
- aiStandardHair : a new physically-based hair shader was added, with much more accurate specular and transmissive scattering based on the d'Eon model, better diffuse scattering for dirty hair, melanin controls, and simple and intuitive parameters.
- aiStandardVolume : a new volume shader was added, usable for rendering a wide variety of volumes. The shader provides independent control of density, scattering color and transparency, in a way that is energy conserving by default. Fire can be rendered using blackbody emission driven by temperature. Displacement can be used to add more detail to volumes. This supersedes the density volume shader, which has been removed.
- Utility shader set : a large number of Arnold utility shaders are introduced in MtoA 2.0.
- Two-dimensional dithered sampling: most samplers (e.g. soft shadows, indirect illumination, depth of field) will now take advantage of dithered sampling, which improves the visual distribution of noise specially at low sample rates.
- Quad lights: a new sampler has been developed that reduces noise for surface lighting, specially especially in unoccluded regions. For debugging and for comparisons with the previous sampler, the global options.enable_new_quad_light_sampler can be disabled (this control will be removed in a future update).
- Cylinder lights: sampling has been improved, significantly reducing noise inside volumes or where cylinder lights are located near other surfaces.
- Disk lights: a novel sampling algorithm has been implemented for disk lights which can greatly improve their rendering quality when shading points near the disk's surface, particularly in volumes.
- Russian roulette: on average better performance for hair, transmission and volume scattering.
- Caustic noise reduction: a new method was added to reduce noise from caustics. The global option indirect_specular_blur controls the trade-off between more accurate noisy renders at 0.0, and more blurry biased renders with reduced noise at higher values.
- Faster opacity mapping: opacity-mapped transparent surfaces, such as tree leaves, are now sampled more efficiently and can render up to 20% faster, specially in machines with many threads.