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• There are two new optional controls for path-traced subsurface scattering - Attribute "trace" "int sssautobias" and "trace" "float sssbias". In the rare cases where the automatically computed bias for path-traced subsurface scattering needs tweaking, one can set "sssautobias" to 0 and "sssbias" to a desired value such as 1e-6. The default values are 1 for "sssautobias" and 1e-4 for "sssbias".

• Allow volumes to output their aovs AOVs via PxrTee.

• The PxrPrimvar built-in names "curvature_u" and "curvature_v" for principal curvatures can now also be written "curvatureU" and "curvatureV". This is for forward compatibility with the OSL version of PxrPrimvar in RenderMan 24.

• We have deprecated the behavior where connecting a utility pattern to a PxrSurface node forces uncached opacity computations. This has been seen to be a major performance detriment, but can be re-enabled with Option "user" "int utilityPatternForcesOpacity" [1].

• Added support for OpenEXR Arbitrary Metadata.
• PxrAttribute has a new resultI output to allow users to chain PxrAttribute nodes.

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• Rendering with adaptive sampling after a breakpoint and resume took up to 20x longer than when uninterrupted; this was due to missing data in the checkpointing output file and has been fixed.
  

• Fixed a bug in OSL trace() that could happen when hitting multiple objects within a batch of rays.

• Fixed a bug that could return garbage derivatives on failed texture lookups from OSL.

• Fixed a bug that could result in bad texture derivatives at UDIM boundaries.

• Fixed offscreen decimation of dicing rate incorrect behavior with a custom ScreenWindow.

• Fixed out-of-bounds vector access when a OSL spline is provided with only a single control point.

• Fixed incorrect default for the number of textures in PxrTileManifold and PxrRandomTextureManifold.

• Fixed rare holes in alpha channel due to missing ray hits on subdivision surfaces with intricate detail. (The holes were visible when looking at the alpha channel with gamma=0.)

• Fixed a bug where derivatives were uninitialized when fetching uniform attributes and options with OSL getattribute().

• PxrSwitch artifact when connecting a pattern to the index parameter.

• Fixed cases where texture3d() could lead to uninitialized values in derivatives.

• Fixed a bug where AreaScale of mesh lights was not properly updated during interactive updates.

• Added fix for shadow bump terminator index error in PxrDiffuse and PxrDisney.

• Optimized a pathological case for nested instancing on scene ingestion that can dramatically reduce render startup in certain cases.

• Fixed a bug that could cause intermittent crashes in non-deforming curves.
  

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• Added improvements to light selection learning.

• Improved the behavior of denoised Marschner by changing how the albedo is calculated.

• Improved the degree of noise in scenes with spotlights or ies profiles.
• LocalQueue log improvements.