HtoA 1.9.0

5 November 2015

This is a feature release, with Russian Roulette termination in the Standard shader.

  1. Get the install files on Solid Angle Downloads.
  2. Follow these installation instructions.

This release uses Arnold and OpenVDB 3.0.0.

Binaries available for the following Houdini, Houdini FX or Houdini Education production builds:

  • 14.0.474
  • 14.0.444

and for the following platforms:

  • Linux x86_64 (gcc4.4 for H14, gcc4.8 for H15)
  • Windows 7 x64 (vc11)
  • Mac OS X 10.8+

Please note that Houdini Apprentice and Houdini Indie do not support third party renderers and thus cannot run HtoA.

  • Russian Roulette: The Standard and Lambert shaders now use Russian Roulette termination to more efficiently render with high GI depth. For AA samples 5 or higher the increase in noise is typically very small. Indoor scenes with high GI depth will benefit the most, but also scenes with lots of glass and high refraction/reflection depth. In such scenes we have measured between 1.5x and 5x faster renders. (core#4901)

  • Global shader override: It is now possible to override the shader for all objects in the scene by specifying a shader in the Shader Override parameter on the Arnold ROP. (core#4909)
  • Linear output for Facing Ratio: With this option on, the Facing Ratio shader will output a linear, normalized angle instead of N·Eye (htoa#718)
  • Custom attributes in deep EXR: Just like the regular EXR driver, the deep EXR driver now also supports custom metadata/attributes. (core#4915)
  • Search paths: The procedural and shader search paths can now use both : and ; characters as separators for multiple paths, on all platforms. Texture search paths already supported this. (core#4897)
  • Render options and stats in EXR metadata: Several global render options, such as sample settings and ray depths, are now stored in the image file as EXR metadata. We also store a few render stats, such as date, used memory, number of polygons and curve segments. These EXR attributes use a path-like metadata layout, e.g. "arnold/options/AA_samples", "arnold/stats/memory/peak", or "arnold/host/hw". We might add a few extra attributes in future releases, and perhaps rename some existing attributes based on customer feedback. (core#4849, core#4860)

  • Env var expansion in procedural nodes: The procedural.dso parameter now supports expansion of environment variables delimited by square brackets, similar to the env var expansion in searchpaths in the options node. (core#4937)

  • Removed size limit on node and metadata names: Node names, node entry names, and metadata item names no longer have any size limitations. (core#4932)

  • Report memory for smooth derivs: The memory usage summary for polymeshes now includes a separate line to account for subdiv_smooth_derivs storage. (core#4925)

  • Incorrect render with matte surfaces behind volumes such as VDB. (core#4918)
Incompatible changes
  • Renamed sss and volume sampling options: The global options volume_indirect_samples and sss_bssrdf_samples have been renamed to GI_volume_samples and GI_sss_samples respectively, for consistency with the other existing sampling options (GI_diffuse_samples etc). The old names will still work, as we have added them as deprecated synonyms, but will result in warnings in the log files. We recommend that any client code (such as proprietary DCC plugins) is changed to use the new names. (core#4940)
  • Default sss samples: The default value of the newly renamed GI_sss_samples option has been changed from 3 to 2. (core#4940)


See also the Arnold release notes for the full list of core enhancements.

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