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Release Date

November 20, 2017


This version uses the Arnold core.


On Windows, C4DtoA 2.0 and later require the Visual Studio 2015 redistributable 


  • New randomwalk sub-surface scattering algorithm: A new, more accurate way of calculating SSS has been added. Unlike the current empirical BSSRDF method based on diffusion theory, this new method actually traces below the surface with a real random walk and makes no assumptions about the geometry being locally flat. This means it can take into account anisotropic scattering like brute-force volume rendering and produces much better results around concavities and small details. It can also be substantially faster for large scattering radius (i.e. large mean free path) compared to the old method. On the other hand, the new method can be slower in dense media (i.e. small mfp), does not support sss_setname for blending two surfaces together, may require redialing materials to achieve a similar look, and is more sensitive to non-closed meshes, "mouth bags", and internal geometry potentially casting shadows. The default is to use the old empirical diffusion method in order not to break the look of existing scenes. 

  • New car paint shader: We are now shipping a dedicated shader for car paint, which can be thought of as the combination of a simplified version of the standard_surface and flakes shaders. This shader can create a wide range of car paint looks without having to connect several nodes. For example, a pearlescent effect can be easily added to both the specular and flakes layers by simply tweaking a few parameters such as Specular > Flip-Flop and Flakes > Flip-Flop. An arbitrary number of layers of flakes can be used (Flakes > Layers). The flakes at a deep layer are covered by the ones closest to the surface and more tinted by pigments (specified by the Transmission Color parameter). 

  • New licensing dialogs:

    • Connect to License Server: Allows you to edit the address of the Solid Angle RLM and Autodesk NLM license servers.

    • Get Diagnostics: Displays detailed information for troubleshooting licensing issues.



  • Flakes shader improvements: The Size parameter is replaced by the Density parameter, which makes it easy to control the size and number of flakes. Alpha channel can be used as a mask. The new flakes shader supports non-disc shapes and 3D flakes, which are used to render gemstone inclusions like Goldstone, for example. 
  • Shadow matte shader improvements: We have revamped and simplified the shader to make it easier to use, and fixed a number of long-standing issues: Indirect illumination now fills the global diffuse_indirect and specular_indirect AOVs, so we have removed the shader’s (confusingly named) indirect_diffuse and indirect_specular AOVs. Self-reflections are no longer rendered. A new Specular > IOR parameter was added to control Fresnel reflection. The new enum parameter Background can be set to either scene_background (default) or background_color, which allows connecting a specific texture in the Background Color parameter slot. Parameter Alpha Mask was added to control whether the alpha must be opaque or if it has to contain the shadow mask. The Offscreen Color parameter is moved to the Arnold Tag of the Background object.
  • Cellular option added to the triplanar shader: The triplanar shader now supports projection through Voronoi cells using the new Cell parameter. The rotation angle of the projected texture for each cell can be controlled with the Cell Rotate parameter. Cells can be smoothly blended using the Cell Blend parameter.
  • Subdivision frustum culling: Subdivision patches outside the view or dicing camera frustum will not be subdivided. This is useful for any extended surface that is only partially visible as only the directly visible part will be subdivided. Similarly, no subdivision work will happen if a mesh is not directly visible. This can be turned on globally in the Arnold Render Settings > Main > Subdivision by setting Frustum Culling on and can be turned off for specific meshes with Frustum Ignore in the Arnold Tag > Subdivision. The Frustum Padding parameter in the render settings adds a world space padding to the frustum that can be increased as needed to minimize artifacts from out-of-view objects in cast shadows, reflections, etc. Note that motion blur is not yet taken into account and moving objects might require some additional padding.
  • Transmit AOVs in the standard surface shader: The standard_surface shader with transmission can now pass through AOVs, by enabling the Transmit AOVs parameter. If the background is transparent, then the transmissive surface will become transparent so that it can be composited over another background. Light path expression AOVs will be passed through so that for example a diffuse surface seen through a transmissive surface will end up in the diffuse AOV. Other AOVs can also be passed straight through (without any opacity blending), which can be used for creating masks for example. 
  • Support for light linking of volumes: Just like with surface shapes, Arnold now obeys light group assignment on volume shapes and surfaces with volumetric interiors.
  • Display OCIO color spaces grouped by families


  • The Size parameter is replaced by the Density parameter in the flakes shader.

  • The Offscreen color parameter is moved from the shadow matte shader to the Arnold Tag of the Background object.

  • The indirect_diffuse and indirect_specular AOVs of the shadow matte shader are removed. Indirect illumination now fills the global diffuse_indirect and specular_indirect AOVs.


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