21 October 2016

This is a feature release, introducing portal lights and implicit surfaces.

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

This release uses Arnold and OpenVDB 3.1.0.

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

  • 15.5.632
  • 15.5.607
  • 15.5.565

and for the following platforms:

  • Linux x86_64 (gcc4.8)
  • Windows 7 x64 (vc14)
  • Mac OS X 10.8+ (clang7.3)

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

  • Implicit surface plugins: Through the volume plugin API, volume plugins can now provide implicit surface fields. The implicit node has been extended to use these plugins with a new dso parameter, as well as a field_channel parameter to specify which channel from the volume plugin contains the field information. Usually these plugins will provide a signed distance field or level set, so be sure to set the solver to "levelset" in that case on the implicit node. For the first implementation in HtoA, only OpenVDB files containing levelset are supported in the new Arnold Implicit Surface OBJ. (core#5365, htoa#830)
  • Light portals: Skydome lights can now use portals to reduce noise for interior scenes, where light comes into through relatively small openings. Light portals are quad_light nodes with parameter portal on, and instead of emitting light these will be used to guide skydome light sampling. Light portals must be placed to cover all windows, doors and other openings through which skydome light comes into the scene. (core#4720, htoa#828)
  • OpenVDB motion blur optimization: Faster rendering of motion blur from physics simulations, between 25% and 80% in test scenes with strong motion blur. The new velocity_outlier_threshold parameter controls filtering of noisy velocities. The default value 0.001 should have little to no visual impact, setting it to zero disables filtering entirely. (core#5213, htoa#837)
  • Discard polymesh normals with Catmull-Clark subdivision: Because they are unused, polymesh normals are skipped when Catmull-Clark subdivision is detected, resulting in faster export and slimmer .ass files. The normals are kept in the case of linear subdivision. (htoa#837)
  • Diffuse albedo AOV: Core shaders will set the built-in diffuse_albedo AOV. Custom shaders can be modified to set it if needed. (core#5485, htoa#828)
  • Shadow matte AOV: Makes available the value from the API AiLightsGetShadowMatte() call in a built-in shadow_matte AOV. (core#5486, htoa#828)

  • String length limits: There are no longer any limits on parameter name, metadata name, message and filename lengths. (core#3320)
  • Fixed crash caused by out-of-range crease indices after a Voronoi fracture. (htoa#829)
  • Fixed regression that disabled zoom motion blur (htoa#831)
  • Fixed Houdini Indie on systems using wide characters (htoa#820)
  • Fixed OpenVDB volumes parts missing in some cases with multiple grids (core#5547)

  • Fixed translation and UI logic for AA_sample_clamp and AA_sample_clamp_affects_aovs. (htoa#832)


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

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