13 December 2023

_{Text Overlay imager available in 7.2.5.0}

Arnold 7.2.5.0 is a feature release bringing major GPU changes, global light sampling with volumes, improved distance shader, an overlay imager, faster OIDN denoising, and many other improvements and fixes.

GPU renderer overhaul

A large part of the GPU renderer was rewritten using NVIDIA OptiX 8. This allowed numerous improvements such as much faster startup times and better scaling on multiple GPUs. Production scenes with large numbers of textures should also be faster to render and use less GPU memory. (ARNOLD-9882)

• Better GPU startup time: The cold cache pre-population time is up to 14x faster than before. This means that the time to first pixel of the first few renders after an Arnold upgrade will now be significantly faster. This overhead is now low enough that we no longer do a cache pre-population step.

  

• Better multi-GPU scaling: Render time scaling with multiple GPUs has been improved in scenes with many AOVs. When adding a second GPU, the robot soldier scene with 9 AOVs goes from having just a 1.1x speedup in the previous version of Arnold to a 1.7x speedup in Arnold 7.2.5.

• Newly supported features: the following features are now supported on GPU:

  • multiple render sessions (ARNOLD-14145)
  • autobump on per-face displacement shaders, previously, autobump would use the first shader applied. (ARNOLD-12796)
  • motion blur on the sphere primitive (ARNOLD-13458)
  • shader parameter on skydome lights (ARNOLD-13641)
  • polygons edge type in the wireframe shader (ARNOLD-12804)
  • OSL LPE writing via debug closures (ARNOLD-13907)
  • image shader file wrap mode (ARNOLD-12578)
  • ID mode in utility shader (ARNOLD-14159)
  • edgelength mode in utility shader (ARNOLD-14122)
  • the GPU texture filtering logic has been improved such that there is a closer match to the CPU renderer (ARNOLD-12578)
  • a number of fixes have been made to the GPU color management logic such that there is a closer match to the CPU renderer when rendering multiple sessions with different color management setting (ARNOLD-12382)
  • atmosphere_volume shader can be used in volume containers (ARNOLD-8605)

• Improved performance: The following production scenes show improved startup time better scaling on multiple GPUs, lower memory usage and faster rendering. The speedups and memory gains are scene dependant and are more visible on scenes with large number of textures.

Scene by Sohrab Esfehani.

Enhancements

• Global light sampling in volumes: Global light sampling is now supported in volumes. The render time speedup when using global light sampling in volumes depends on the number of lights, but even scenes with only a few lights are faster to render. (ARNOLD-13095)

Below is an equal time render comparison of a scene containing 351 motion blurred mesh lights inside an atmosphere_volume.

• Improved thick curves intersector: Curves in thick mode are on average 10% faster (in some cases, more than 100% faster) and they look better in closeups. (ARNOLD-2875, ARNOLD-8549 and ARNOLD-14391)

• Distance shader in reflections: The distance shader now properly handles secondary paths such as reflections. (ARNOLD-13883)

• Overlay imager: A new imager that allows you to decorate or tag your renders by printing text over the rendered images. Overlay text can use any of the system fonts (TrueType or PostScript), or custom fonts defined via the OPENIMAGEIO_FONTS environment variable. You can include scene and system information, and render statistics, with pre-defined tokens, such as <frame_time>, <samples>, and <camera>. See the Overlay Imager documentation for the full list of tokens. (ARNOLD-14188)

_{Overlay imager used to add text to the rendered image}

• GPU denoising in Intel Open Image Denoise: The Intel denoiser was upgraded from version 1.4.1 to 2.1.0, which brings real-time denoising through NVIDIA and Intel GPU support. (ARNOLD-12547)

• Toon light-group AOVs: The toon shader now outputs AOVs for direct lighting from lights that have a label in their aov parameter. The toon light-group AOVs are named with the toon aov_prefix parameter. For example, if a light has aov = "keylight" and a toon shader has aov_prefix = "myprefix_", then the toon light-group AOV is named "myprefix_keylight". (ARNOLD-9602)

• Automatically create non-existent paths to tx file: Generating a .tx file (maketx, autotx, AiMakeTx) now works even if the paths to the output .tx file do not exist: Arnold now creates those paths. (ARNOLD-14703)

• Scene unit conversion for light intensity: Scene unit conversion is now supported for light intensity in nested procedurals. If a procedural contains a light and its scene units do not match the procedural units, the light intensity is scaled to match the procedural. Conversion is in place for Arnold ass file procedurals, but we do not yet support USD and arbitrary procedural formats. (ARNOLD-9205)

• Scene unit conversion for volume density and emission: Scene unit conversion is now supported for volume density and emission in nested procedurals. If a procedural contains a volume and its scene units do not match the procedural units, volume density and emission are scaled to match the procedural. Conversion is in place for Arnold ass file procedurals, but we do not yet support USD and arbitrary procedural formats. (ARNOLD-9206)

• Faster overlapping volumes: Arnold renders a few percent faster when there are many overlapping volumes. (ARNOLD-14353)

• Improved profiling: Procedural and volume intersection times are now listed separately, instead of being included with the parent BVH. Profiling has also been added in other areas, in particular multithreaded code where helper threads were not being accounted for. This should result in higher quality statistics. (ARNOLD-14443)

• Updated Autodesk Network License Manager:: Autodesk Network License Manager (NLM) server version 11.19.4.1 is available and includes support for RHEL/Rocky Linux 9 operating systems. You can find the NLM installer in the license/installer folder, and from the Arnold License Manager. (ARNOLD-14429)

USD Enhancements

• USDZ files supported as file format: You can render usdz files with kick, and load them with the usd procedural. usd#1726.

• Orthographic cameras in Hydra: Orthographic Cameras are now supported in the Hydra render delegate. usd#612.

• Pixel Aspect Ratio in Hydra: The Arnold Render Delegate now supports the pixelAspectRatio parameter in RenderSetting primitives usd#658

API changes

• Multiple render sessions on GPU: The GPU can now render multiple render sessions at the same time. (ARNOLD-14145)
• Font API: A new API AiFontGetFamilies and AiFontGetStyles returns the list of available system fonts (e.g. "Arial", "Times New Roman") and font styles (e.g. "Regular", "Bold", "Italic"). AiFontGetFilename returns the path of the file that defines a given font family and style. (ARNOLD-14395)

Incompatible Changes

• Minimum NVIDIA driver requirements for Arnold GPU: Arnold GPU requires 535.104 or higher drivers on Linux and 537.13 or higher on Windows.
• GPU cache pre-population deprecated: The GPU cache pre-population has been deprecated and calling these functions will now do nothing. (ARNOLD-12135)

Bug Fixes

• ARNOLD-14380 - Crash when compiling OSL shaders interactively
• ARNOLD-14102 - Smart opaque does not work properly with curves
• ARNOLD-14115 - OSL getattribute should return builtin uvs as fallback
• ARNOLD-14269 - Procedural interactive reload was not thread safe
• ARNOLD-14304 - Report when texture cache flush is delayed
• ARNOLD-14435 - maketx does not show all messages
• usd#1709 - Procedural failures if schemas are present
• usd#1713 - Fix coding error "attempt to get string for GfVec4f"
• usd#1732 - Force the color AOV to be interpreted as the Arnold beauty pass
• usd#1735 - Fix usdskel geometry and motion blur interpolation outside the keyframe boundaries
• usd#1524 - Fix material binding on instances under a SkelRoot
• usd#1718 - Support primvars:arnold attributes in Arnold typed schemas

System Requirements

• Windows 10 or later, with the Visual Studio 2019 redistributable.
• Linux with at least glibc 2.17 and libstdc++ 4.8.5 (gcc 4.8.5). This is equivalent to RHEL/CentOS 7.
• macOS 10.13 or later.
• x86-64 CPUs need to support the SSE4.1 instruction set. Apple Mac models with M series chips are natively supported.
• GPU rendering works on Windows and Linux only and requires an NVIDIA GPU of the Ampere, Turing, Volta, Pascal, or Maxwell architecture. We recommend using the 535.104 or higher drivers on Linux and 537.13, or higher on Windows. See Arnold GPU for more information.
• OptiX™ denoiser requires an NVIDIA GPU with CUDA™ Compute Capability 5.0 and above.