RenderMan XPU™ - Pixar’s new hybrid CPU + GPU rendering technology makes its first debut outside the studio in RenderMan 24. This next-gen rendering engine is being adopted internally at Pixar for look development work and will now be available to commercial RenderMan customers as well for similar tasks.
Lama - A state of the art material layering system developed at Industrial Light & Magic introduces a modular approach to building material networks and includes recent shading R&D work on energy conservation and dispersion. These new physically based shading nodes will also form the basis of future MaterialX support in RenderMan.
Stylized Looks - Move beyond physically based shading and lighting and into a world where you can easily create a variety of styles for your projects - create unique styles thanks to Non-Photorealistic rendering. With Stylized Looks you can non-destructively control outlines, create sketch patterns, and develop a huge range of unique looks, including Anime, by using the same familiar toolset. Stylized Looks is available only in the Commercial version of RenderMan.
Interactive Instrumentation and statistics - (coming in a later beta) Watch your rendering resource usage live, thanks to a completely redesigned statistics system with focus on interactivity and extensibility.
OpenColorIO - Robust support for the industry standard ACES color management system and other color spaces in all bridge products including the interactive RenderMan Image Tool.
New patterns, such as PxrHexTileManifold and PxrPhasorNoise - We are continually working to provide more artistic options for your look development, in this case, a Hex Tiling manifold and a new noise pattern called Phasor Noise. The technology within these patterns has seen production proven use used within different entities of the Disney organization, including Pixar and ILM.
Light Baking - Greatly enhance your real-time and VR rendering needs by baking your lighting to 2D texture maps or Point Clouds.
Professional Artist Tools - Support for Maya, Blender, Katana, and Houdini, including new support for LPEs and AOVs in Solaris, Houdini’s USD-centric toolset.

Patterns are now OSL - We have converted the great majority of RIS' C++ patterns to OSL. This conversion allows us to share code between RIS and XPU, which in turn gives you confidence that the renders you see from RenderMan XPU are representative of what you will see in RenderMan RIS. C++ patterns are still supported, but they will only work in RIS.
Blender - New support for cutting edge RenderMan features in the popular open source content creation tool
Better Sampling - New blue noise dithering improves the visual appearance of noise by organizing the sampling pattern distribution, resulting in a perceptually cleaner image sooner.

RenderMan XPU™

Pixar’s hybrid solution for CPU + GPU rendering combines available computing resources to accelerate production path-tracing. Starting from a system architecture that can leverage the latest developments in many-core CPU and GPU hardware, separately or in combination, RenderMan XPU™ is being built to handle the scale and complexity of Pixar’s feature animation projects. Its first use in the studio has been focused on detailed look-development tasks, and this integration into Pixar’s pipeline was a significant milestone, with more roles and capabilities to come. The RenderMan team is excited to begin sharing this ongoing development work with our commercial customers.

For further details about RenderMan XPU™, see the following documentation sections:

XPU - for an overview of XPU in RenderMan 24
Lookdev with XPU - for details on lookdev with XPU
XPU Differences to RIS - to understand the differences between XPU and RIS
XPU Notes - for known limitations with beta1

The Artist Experience

RenderMan version 24 offers a holistic experience, with tools that improve artist workflows and complement the creative process. By collaborating closely with Industrial Light & Magic and Pixar Animation, the latest innovations represent industry developments that have been battle tested in the most ambitious VFX and animation in the world.

The new shading systems are complemented by an all-new artist-friendly stats system, making the new non-photorealistic toolset an integral and seamless part of the RenderMan experience, allowing for new creative possibilities.

Dispersion - The new layered materials system supports a sophisticated prismatic fringing effect for refractive objects.
USD - hdPrman includes dynamic rendering of LPEs and AOVs in all compatible Hydra viewers, such as Houdini’s Solaris and USDView.
Bump Roughness - Innovative system developed at Pixar Animation for rendering micro details such as scratches efficiently and automatically, without expensive sampling.
Bloom — Add gleams and blooms directly to your live renders with this physically-based tool for RenderMan’s Image Tool (IT).

Additional Features

RenderMan version 24 also includes:

OpenVDB — New support for OpenVDB 6.2.1.
OpenEXR — Updated to version 2.3.
Updated API — New changes to plug-in APIs and developer resources.

VFX Reference Platform 2019 — All plug-ins are now updated to the new standard.

Known Rendering Differences - RIS 24 vs RenderMan 23

As with every RenderMan release, we continue to push the capabilities of the renderer forward. At times, this can result in minor look differences from one major version of RenderMan to another. We have added backward compatibility flags and switches when possible.

OSL pattern differences to the old C++ implementation – particularly with noise patterns. The default implementation of various noises in OSL is different than it is in C++, so if your renders use these noises, you will see different results. We have provided a backward compatibility switch on the relevant OSL patterns. However, we don't recommend using the switch unless you absolutely must because the patterns will have better performance in their native mode.
OSL noise differences. In RenderMan 24.0, we have upgraded to OSL 1.10. Several of the noise patterns have changed implementations in this new version of OSL, causing look differences if you had written your own OSL patterns that leveraged the affected shadeops.
The PxrPathTracer and PxrUnified integrators now treat subsurface scattering the same as diffuse with respect to the "maxIndirectBounces" integrator parameter and "maxdiffusedepth" Attribute: 0 means direct diffuse and "direct" subsurface scattering; 1 means 1 bounce of indirect diffuse and 1 bounce of subsurface scattering, etc. Please note that this results in a slight look change between R24 and R23.x. We feel that this change is more intuitive for artists and TDs. It is also consistent with XPU. Also please note that this results in slight performance differences between R24 and R23.x. R24 renders slightly slower in scenes with large amounts of subsurface. If you want to have the same look as R23.x with the same performance characteristics, you can set an Attribute on any subsurface object in your scene to set "maxdiffusedepth" one less than it was previously.
PxrSurface now supports two lobed Henyey-Greenstein for single scattering. Existing scenes will need to migrate the "g" parameter to the "g0" parameter.
PxrMix parameter "mix" is now "mixer". This change was necessary because the nodes are now OSL, and "mix" is a reserved keyword in OSL. The parameter "clampMix" changed accordingly to "clampMixer".
The OSL texture3d() function no longer transforms the P parameter from world space to object space.
VFX Reference Platform 2019 support. Note that in some instances, the look will be affected if you have written your own OSL patterns as at least one OSL noise functions has changed. It is known that at least one of the built-in noise operators within OSL has changed, so if you have written your own OSL patterns that use the built-in noises, you may see differences.
PxrFlake: Fixed moire artifacts and lower the cost of multiple flake layers (octaves). The pattern has changed but has the same characteristics as the previous version.
Blue Noise: In RenderMan 24, we are introducing a new tiled blue noise sample scheme that builds on top of our pmj02 samples. This new sampling scheme shows most visual improvement for low sample counts and simple sample domains such as strong motion blur, strong depth of field, direct illumination from large area lights and dome lights, ambient occlusion, and volumes. When the image is fed to a denoiser, the new scheme can also help the denoiser better distinguish between noise (that should be smoothed) and actual image features (that should be preserved). Ironically, the new scheme does not give lower error or improved convergence for each pixel by itself. But the visual quality is improved when the pixels are considered together. An option is being provided to revert back to the old random number sample sequence if you need the old behavior
The default "pixelfiltermode" setting for the Hider is now "importance" instead of "weighted". This change was made to align RIS to XPU. If you are not using the denoiser and are using RIS, you may want to consider changing the mode back to "weighted" because in many cases it will render to full convergence more quickly than if "importance" is used. However, if you're using the denoiser, you need to use "importance"
The default for glassIor initialization within the code was set to match the Args file. If you see differences with shading, you may need to explicitly set the IOR to 1.0 within the shading network.
For volumes, Oi used to return a single float value to an AOV when a color is expected. The transparencyAccum of PxrUnified is now a color. This allows PxrUnified to correctly output a colored Oi when given volume with colored extinction. Previously, the monochromatic transparencyAccum was promoted to colored Oi and this is wrong.
The PTM occlusion term is no longer automatically applied to the denoising albedo

Known Limitations for RIS in beta1

Performance:
- OSL startup. We have upgraded to OSL 1.10 for both RIS and XPU in RenderMan 24. We have found that this upgrade (and its dependencies) have slowed downtime to start up. We will work in the time between beta1 and the time we release to see if there is anything we can do to mitigate this problem.
- Volume integration with patterns. Because of the switch from C++ to OSL patterns and the sensitivity of volume integration to pattern execution, there are performance regressions with volumes in RenderMan 24 compared to RenderMan 23 that remain to be addressed.
- There are other performance slowdowns we have seen in RIS compared to RenderMan 23. They only occur in some circumstances. We will be working to address as many of these as we can.
Known crashes:
- OSL networks wired into PxrVolume. If anything but trivial OSL patterns are wired into the inputs of PxrVolume, RenderMan 24 will crash.
Lama:
- Several defaults may change between beta1 and beta2.
- Minor bugs
Color Management:
- There are a few nodes that have not been made aware of color management. PxrEnvDayLight is one such node.
Interactive instrumentation/statistics:
- This feature is coming in beta2
OSL Patterns:
- <primstr:nameofvalue> needs to be implemented as a way of specifying primvar references within dynamic filenames. This is being done to match XPU.
Bridge Products:
- Preset Browser:
  - Continued improvements for ACES/Color Management support
  - Continued improvements for moving Stylized Looks between DCCs

Pipeline and Coding Details and Differences

This section contains a listing of the items that have changed within RenderMan RIS and our Bridge Products that affect your pipeline and any code that you may have surrounding RenderMan.

VFX Reference Platform 2019. RenderMan 24 supports the VFX Reference Platform 2019. If you haven't already upgraded your systems with the requirements for the VFX Reference Platform 2019, you will need to do so in order to run RenderMan 24.
OSL 1.10: We have upgraded our OSL to version 1.10. Note that in some instances, the look will be affected if you have written your own OSL patterns as some OSL noise functions have changed.
OSL shaders now support connecting scalar values to individual elements of an array shader parameter in the same way C++ shaders do
Allow explicitly setting dynamic array parameters in OSL shaders
To take advantage of the new Color Management and Bump to Roughness features, you will need to expand your txmake workflows when converting your textures for RenderMan
_MAPID_ and atlasStyle will become deprecated in future releases. Please use <UDIM>, <u><v> and <U><V> for all texture atlas specifications
The PxrPrimvar built-in names "curvature_u" and "curvature_v" for principal curvatures are now "curvatureU" and "curvatureV" to better follow naming conventions.
Dynamic String Construction within any in-house patterns: XPU does not support dynamic string construction within Patterns, so if your Studio has any in-house Patterns that do this, you will need to pre-compute any strings you need.
Dynamically Building Filenames for Textures: While XPU does not support dynamic string construction, we are adding the capability to specify primvar references within a filename to have the system dynamically reference a filename for you. This feature will be in beta2 for XPU, but is available in RIS now. Use the <primstr:varname> token for this.
The contrast-v22 and variance-v22 adaptive sampling metrics continue to be deprecated. They will be removed in a future RenderMan release.
In PxrUnified, volume render Oi returns single float value to an AOV when a color is expected. The transparencyAccum of PbsWavePayload is now a color. This allows PxrUnified to correctly output a colored Oi when given volume with colored extinction. Previously, the monochromatic transparencyAccum was promoted to colored Oi and this is wrong. It is impossible to correctly composite such volumes with only the alpha channel a correct colored Oi is required.
RfK: the "prmanPattern" terminal type has been removed from material nodes.
RfK: The widget is now automatically set to "null" for all OSL outputs, so there is no longer a requirement that shader writers add this to their output parameters' metadata
RfK: Alembic_In_Prman has been removed as the multithreaded advantage it had has been supplanted by the new multithreading features in Alembic_In from Foundry
RfH: all RenderMan node versions have changed to ::2.0. please convert your nodes with provided script.
RfH: RenderMan errors are now warnings in Houdini

More Details

More New Features in RIS

PxrSurface now supports two lobed Henyey-Greenstein for single scattering. Existing scenes will need to migrate the "g" parameter to the "g0" parameter.
A new PxrRadialDensity pattern defines a spherical density gradient in a volume container.
Color management support. Added basic ACEScg support. There is now a scene-wide control defining the primary colorspace (Rec709 or ACEScg). Lights, light filters and nodes with color space controls (PxrBlackBody, PxrHairColor, PxrTexture, etc) will obey this setting when set to "Scene". Patterns can override the source and destination colorspace if need be.
You can now output AOV's in OSL via the closure debug("AOVName"). No other closures are supported, but arbitrary combinations of debug() are supported to provide AOV's. Passing them via get/setmessage() is not supported.
Bump and normal map shadow terminators. There is a new parameter added to all the BxDFs to apply a technique that improves the the abrupt shadow terminator line that appear when strong bump or normal maps are used to emulate micro-geometry. If there is no bump map applied to the BxDF the result produced is exactly the same as it was before. In beta1, by default the technique is turned off. To turn on the technique the user just needs to check the "Bump Shadow Terminator" parameter from the BxDF. This parameter is a global parameter, so its effect will be the same for all the lobes, it means, if it is turned on then it will applied to all the existent lobes of the BxDF (1 in the case of Diffuse but many in the case of Surface). In beta2, we are likely to make the default to be on and remove the per-material control, and instead add a backwards-compabibility option that would globally affect the render. This is available in both RIS and XPU.
Polgyon shadow terminators. We have improved shadowing artifacts on coarse polygon meshes.
RfH: improved user friendliness of cryptomatte in RfH
RfH: apply materials to instance points via instancer
it: Added a simple bloom filter to It
it: Support OCIO color spaces

Bug Fixes

We now correctly combine the two shadow exclusion subsets defined by Attribute "trace" "string shadowexcludesubset" and the "string shadowExcludeSubset" parameter on Light shaders that support this functionality.
RfH: args2hda now supports unicode characters in parameter/shader help
Add a Version string to the rman python module.
PxrUnified no longer clamps "numIndirectSamples" to max 1.
More informative message when the alembic procedural fails to read a RLF file.
RfM: Color and foat ramp widgets are not enclosed in an extra group anymore, if they share the same label as the enclosing group
RfM: The Pixel Variance fields have a five-digits precision instead of 3.
Fixed a bug preventing connections to dyanmically sized array input parameters in OSL shaders
Fixed a crash when loading OSL shaders with dynamic array parameters.
Fixed a bug where, in some cases, 'motionFore', 'motionBegin' and 'dPcameradtime' would be emitted w.r.t to a camera different from the one being rendered
Fixed a bug where scenes with very high light counts could sometimes get stuck for a long period of time during initial scene processing

Known Limitations

Interactive/Live Rendering Limitations

Bucket order or size cannot be changed during live rendering
Changes to Presence do not update when using the opacity cache option
Motion Blur will disappear during interactive rendering with scene changes
Objects are not re-diced during interactive camera edits
Mesh lights cannot be interchanged as geometry without restart.

RenderMan Pro Server

PxrUnified integrator is currently experimental as it does not yet support all the standard rendering features.
Meshlights cannot be instanced
Load on demand procedurals are not supported anymore, all procedurals are now loaded immediately
We do not read point data from OpenVDB files
PxrSurface back diffuse color is not output to the albedo color AOV
Analytical lights placed inside volumes may yield artifacts when made visible to the camera. As a work around, the light camera visibility should be turned off, and a geometry with a similar shape should be used (visible to camera, invisible to transmission and indirect rays), with the proper emissive bxdf.
Using the ' . ' character in the handle for an OSL shader could cause unpredictable results during re-rendering.
Per-Instance baking is not supported, only the reference instance.
3d baking: no direct bake-to-ptex support.
PxrBakePointCloud cannot directly render ptex.
Sample/Display filter plug-ins do not have access to lighting services for light dependent effects, e.g. lens flare.
Adding new mesh light on existing geometry during IPR results in double geometry.
Motion blurred polygons do not motion blur normals when deformed. Use Subdivision meshes instead.
When attempting to access an array primvar, you must first check the size of the array primvar and allocate the appropriate space. Not doing so may lead to a crash.
Points and curves cannot be used as geometric lights.
Deformation motion blurred volumes don't currently work with densityFloatPrimVar or densityColorPrimVar. You will need to use a PxrPrimVar node connected to densityFloat and densityColor instead.

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Contents

Welcome to RenderMan 24.0b1!

New Features in RenderMan 24.0b1