Arnold for Maya 5.5.0 (What's New in Maya 2026)

Improved, more realistic shadows for glass objects

Transparent objects like clear glass now cast shadows. The look of the shadow is controlled by the new transmission_shadow_density parameter on theopenpbr_surface and the standard_surface shaders. (ARNOLD-6881, ARNOLD-15863, ARNOLD-15828)

0	0.5	0.9	1

	Transmission shadow density = 0	Transmission shadow density = 1
Caustics off
Caustics on

Improved Global Light Sampling (GLS) on glossy materials (MtoA 5.4.8)

7.3.5, fixed AA	7.3.7, fixed AA

Optimized Cryptomatte and GPU support

Arnold now has an internal implementation of Cryptomatte that adds support for GPUs and improves performance on CPU. Cryptomatte now consumes less memory for samples, making it easier to use higher AA settings, progressive rendering, and adaptive rendering (when properly used with FIS). In a simple scene rendered at 640x480 resolution with three cryptomattes the below table shows improvements in peak memory. (ARNOLD-11042)

Various normal types for triplanar

shading	smooth and displaced

shading	smooth before displacing

Arnold for Maya plugin enhancements

Arnold RenderView enhancements

• Arnold Render View - Log Viewer: Add tabs for viewing saved logs and loading log files: Tabs have been added to the Log Viewer to allow you to copy from the live log and load log files from disk (ARNOLD-15640)
• New Arnold RenderView Icons: Arnold RenderView has had new improved DPI-aware icons (ARNOLD-14264)

Performance enhancements

• Faster OpenVDB volume intersection: Intersecting OpenVDB volumes are optimized for many-cores. Scenes where volume::intersection is a sizable component of render time can see large speedups. One scene where it accounted for 73% of render time on a 128-core machine saw the volume::intersection time drop to 16% of total time, for an overall 3x speedup in render time. (ARNOLD-15448)
• Faster uv_camera baking: The uv_camera.grid_size default is now 0 instead of 16, where 0 specifies that the grid_size is automatically chosen. Using the new default, baking a sphere with 800k triangles is now 6.5x faster than the previous default. (ARNOLD-15441)
• Improved instancing in the Alembic procedural: Instanced geometries are now better handled in Alembic. This fixes the known issues with make_instance, which is now enabled by default. (ARNOLD-15209, ARNOLD-8364, ARNOLD-8924, ARNOLD-7818)
• Optimized handling of interactive object visibility changes: Improved detection of visibility changes gives faster scene updates. (ARNOLD-15708)

MaterialX Enhancements

• Improved MaterialX support: MaterialX has been upgraded to v1.38.10-OpenPBR. This new version brings support for the OpenPBR MaterialX node, improved Lama support, and new nodes such as NPR. see [v1.38.10] ( https://github.com/AcademySoftwareFoundation/MaterialX/releases/tag/v1.38.10), [v1.38.9] (https://github.com/AcademySoftwareFoundation/MaterialX/releases/tag/v1.38.9) release notes for details. (ARNOLD-15659)
• Improve interoperability between Arnold and MaterialX shaders: It is now possible to connect Arnold closure shaders such as standard_surface and openpbr_surface to MaterialX surfaceshader shaders such as mix. (ARNOLD-15238)
• MaterialX OSL closure support: The OSL closures defined by MaterialX for definition of layered physical materials have been ported to Arnold. For example, all the closures needed to implement the OpenPBR are now available in OSL. See OSL Shaders for more information.

Coated diffuse material created with OSL MaterialX closures.

Arnold Enhancements

• Lights in procedural instances: Lights in instanced procedurals are copied for each instance. For example, instances of ASS or USD assets with lights now render the lights properly. (ARNOLD-15657)
• Add more options settings to image metadata: Images with metadata, such as EXR files, now include arnold/AA_samples_max, arnold/AA_adaptive_threshold, arnold/fis_filter, and arnold/fis_filter_width metadata. (ARNOLD-15521)
• Linked color and positions in ramp shaders on GPU : Arnold GPU now supports the linking of individual ramp parameter components for the position, value, color, and interpolation parameters. (ARNOLD-7120)

OpenPBR Enhancements

• New OpenPBR icons: New icons have been added for the aiOpenPBRSurfacein the Hypershade, and the Arnold openpbr_surfaceshader in LookdevX (MTOA-2215)
• Nits per Unit options parameter exposed: Introduced in Arnold 7.3.4.0, the OpenPBR Surface emission_luminance parameter (in nits) is scaled down by the nits_per_unit value (defaulting to 1000) to bring it into Arnold units (MTOA-2080)
• Corrected clamping of OpenPBR metallic lobe: The OpenPBR metallic lobe Fresnel previously exhibited energy gain when the specular_weight parameter was increased above 1. This has been corrected so that the Fresnel conserves energy in this case, saturating to a mirror reflection in the limit of high specular_weight.

USD Enhancements

Installer Updates

Component Updates

API changes

• Imager run once mode: Imagers can now be set to run only once, at the end of a bucket or the end of a completed final frame. This can be useful for particularly expensive imagers and can be enabled via the ImagerProperties::run_once property. (ARNOLD-12191)
• Replace AtImagerSchedule with AtImagerProperties: The imager_prepare API has a new AtImagerProperties structure that provides more control over how an Imager should run. (ARNOLD-15774)Setting Imager bucket / full frame schedules will now work like so:

  imager_prepare { if (run_imager_full_frame)
  properties.schedule_full_frame = true; else
  properties.schedule_bucket = true; }

• Improved return values for device selection API : AiDeviceSelect and AiDeviceAutoSelect now return the AtDeviceSelectErrorCode enum instead of an int to better describe the error status of the API call. (ARNOLD-14652)

  AtDeviceSelectErrorCode
  SUCCESS	Device selection was successful
  FAILURE_NO_DEVICES_FOUND	No Arnold compatible devices found
  FAILURE_NAME	No matches found for options.gpu_default_names regular expression
  FAILURE_MEMORY	No matching device has free memory greater than options.gpu_default_min_memory_MB threshold
  FAILURE_INVALID_ID	Invalid device id in selection
  FAILURE_UNSUPPORTED	Unsupported device in selection
  FAILURE_UNKNOWN	Generic error

• Node API : Added new AiNodeAddDependency to declare an update dependency between a consumer node and a specific parameter on a producer node (a consumer can depend on a producer through multiple parameters). Added another API to clear the dependency between two nodes (for all parameters). Finally, the previous API is deprecated. The same behaviour can be replicated by using the newAiNodeAddDependency API and passing an empty or null string for the parameter, to create a dependency that covers all parameters (this should be used only when absolutely necessary). (ARNOLD-15483)

  AI_API void AiNodeAddDependency(AtNode* consumer, const AtNode* producer, const AtString param);
  AI_API void AiNodeClearDependency(AtNode* consumer, const AtNode* producer);
  AI_API AI_DEPRECATED void AiNodeAddDependency(AtNode* consumer, const AtNode* producer);

• Limit node update recursion: Previously, node updates were propagated up the parent chain for all node types. We now do this for shape nodes only. This can improve node update time. (ARNOLD-15492)
• Avoid unnecessary node updates: Resetting a node parameter to the current value will no longer cause a node update. (ARNOLD-15402)
• Per-parameter update dependencies: Previously, a node update dependency caused a node to be updated whenever the dependency node was modified. We now define these dependencies based on parameters, so the node update is triggered only when one of the specified parameters on the dependency node was modified. (ARNOLD-15483)
• Additional metadata for parameter grouping and types: New metadata added for most base types (such as polymesh, shape, light, and skydome_light to specify information about parameters. (ARNOLD-15674)
  • ui.groups - Information on the grouping of parameters, useful for applications to automate the display of parameters. This metadata was previously available for some shaders only. It is in the form of Group Name 1:param_1 param_2,Group Name2:param_3 param_4
  • ui.hide - This boolean hides a parameter in an interface
  • ray_vis_type - A boolean metadata for parameters that takes a byte value that represents a ray-type mask, for example, visibility, sidedness

Incompatible changes