• In Houdini 22, Karma/husk now renders the frame and entire frame range that’s defined in the USD file (unless you specify the -n 1 argument, or the -f argument).

• husk now initializes the --frame and --frame-count options using the stage metadata startTimeCode and endTimeCode.

• Object-space displacement shading for scale-impervious results.

• When Karma automatically converts textures, it will now use the --opaque-detect imaketx option to remove constant opaque alpha channels from images. This shouldn’t affect rendering, other than to save bandwidth and memory.

• Mipmap texture load on indirect bounces was improved to reduce the impact on render times if they're bottlenecked by file access.

• Karma XPU has improved support for displayOpacity and Af AOVs.

• Memory usage for subdivided/diced meshes is reduced by up to half.

• The MtlX Image VOP provides a Karma Texture Controls recipe. With Karma XPU, the recipe’s Texture Width can now go below 1, allowing sharpening of a texture. With 0, you can even even disable mipmapping completely. If you want to restore the previous behavior, set KARMA_XPU_ENABLE_NEW_TEXBLUR_BEHAVIOR=0.

• The MtlX Standard Surface VOP’s Coat ▸ Color parameter can now have values greater than 1.

• The Bump Shadow Terminator feature on the Render Geometry Settings LOP is now also available for Karma XPU.

• You can now render iso-surface VDBs directly as uniform volumes without having to go the detour via a mesh.

• There’s now improved render visibility support for indirect ray types.

• husk will now skip hvisualize materials when rendering outside Houdini, for example in a farm. The prevents probe materials from being rendered in the final shot.

• husk has a --pass ‹prim_path› flag. When specified, husk searches the Scene Graph Tree for renderpass primitives under /Render. For more information and examples, please read the husk documentation.

• The new --error-summary flag controls the behaviuor of the report creation at the end of the error log.

• husk will now search for the RenderPass primitive under /Render. You can now also render multiple passes in a single husk invocation. For more information see the husk and search for --pass ‹prim_path›.

• The Karma and husk USD schemas now preserve relationships (instead of representing relationships as strings).

• husk now includes the name of the used delegate to create a default file name, for example karma.exr or husk_storm.exr.

• On the Karma Render Setting LOP’s Karma ▸ Lighting Effects tab, you can find new Disable Scene Materials (husk) and Disable Scene Lights (husk) parameters. Note that these are husk options and don’t have any effect on the viewport!

• A new --skip-existing-frames option for husk will look for already rendered frames and skips them. This option is also available as a checkbox on the USD Render ROP’s Husk ▸ Rendering tab.

• A new husk:default_delegate schema provides information about the currently used renderer. This is important for render managers.

• A new husk --karma-percent-of-samples option specifies a percentage of samples at which the render will stop (Karma-only). Please see the husk reference for more information.

• The -o option for the output image file path now works with 3rd party renderers.

• The Texture Material Library LOP lets you directly create and connect textures from a built-in COP network. A pre-configured USD Material COP provides very similar functionality as the MtlX Standard Surface Shader VOP. Find out more on Working with Copernicus nodes.

• The Image Filter LOP lets you apply a list of filters. Filters, available for COP Image Filter Lists, are also supported by this LOP. The node creates a HoudiniImageFilterList primitive on the stage that contains the filters.

• The new Karma Blocker Light Filter LOP authors a USD KarmaBlockerLightFilter prim on the stage. The node uses simple geometry to control the contribution of light in specific areas or create shadows from invisible objects.

• The Karma Ambient Occlusion VOP lets you calculate ambient occlusion on the shader level.

• The Karma Distance VOP computes the normalized distance to nearby surfaces.

• The Karma Curvature VOP calculates the “roundness” of a surface.

• A new Karma Light Filter Attenuation VOP lets you control how light changes over distance. You can choose from various preconfigured models or define a custom ramp.

MaterialX 1.39.5 is now part of Houdini. This version comes with many new nodes.

• The MtlX Flake2D generates a procedural flake pattern in 2D space, suitable for simulating metallic flakes in materials such as car paint.

• The MtlX Flake3D generates a procedural flake pattern in 3D space, suitable for simulating metallic flakes in materials such as car paint.

• The MtlX Fractal2D provides a zero-centered 2D fractal noise in 1, 2, 3 or 4 channels.

• The MtlX Gltf Anisotropy Image lets you create the anisotropic property as seen with brushed metal.

• The MtlX glTF Material is a material defined by the Khronos Group for glTF-2.0. Designed to improve interoperability between MaterialX and glTF-authored shaders.

• The MtlX Hex Tiled Image samples data from a single image, with provisions for hex-tiling and randomizing the image across UV space.

• The MtlX Hex Tiled Normal Map samples data from a single normalmap, with provisions for hex-tiling and randomizing the image across UV space.

• The MtlX Lat Long Image samples an equiangular map along a view direction with adjustable latitudinal offset.

• The improved Karma Whitewater Material recipe now supports a specular layer over a uniform volume instead of having to render both features as separate primitives.

• The Karma Physical Sky LOP now supports portal lights. You can find an appropriate parameter under Sky ▸ Base.

• The Karma Texture Baker LOP now supports the MtlX OpenPBR VOP shader.

• The Karma Texture Baker LOP now has a Cage Mode parameter with three options: Topology Match, UV Match, and Cage Offset.

• On the Karma Texture Baker LOP’s Images tab, there’s a new Save Mip Mapped Texture option that lets you create tiled images for efficient rendering.

• The Karma Sky Atmosphere LOP now ignores the camera far clip distance by default when calculating its contribution for primary rays. To go back to earlier behavior, you can turn off the Ignore Camera Far Clip option in the node’s Advanced section.

• On the Render Settings LOP and Karma Render Settings LOP, the Pixel Filter Size parameter was removed.You can find a Pixel Filter Scale parameter instead. The new parameter is a scaling factor for the (internally pre-adjusted) default filter values. Note that backwards compatibility is supported.

• On the Render Settings LOP’s Karma ▸ Global ▸ Shading tab section, you can now find MaterialX Filter Width and MaterialX Filter Blur parameters. The parameters are multipliers for the Karma Texture Controls on the MaterialX Image VOP.

• The Camera LOP now includes several new exposure parameters from the USD library on the Sampling tab.

• On the SOP Crowd Import LOP you can now find Remove Agent Shapes and Remove Agent Layers parameters to exclude certain parts of the crude from the export to USD.

• The Mask from Bounds LOP’s Value parameter now supports the color4 Type.

• On the Render Geometry Settings LOP’s Dicing section, you can find a new Dicing Z-Importance parameter. This feature optimizes the tessellation rate and decreases memory consumption with lower values.

• The USD Render ROP’s Husk ▸ Python tab has new a new option for a Husk Post-Load script. You can now run a script after the USD stage was loaded, but before any render settings have been configured. A post-load script lets you, for example, define custom render settings. This option is also available for husk.

• The Karma Render Settings LOP now has a Camera’s Far Clip as Background Value option. This mode fills the Depth (Camera Space) AOV with the values of a camera’s far clip value. You can find the new toggle here: Image Output ▸ AOVs (Render Vars) ▸ Utility.

• A new Split Render Products by Render Var option on the Image Output ▸ AOVs (Render Vars) tab of the Karma Render Settings LOP lets you create a separate file per RenderVar. The files will be suffixed with AOV names.

• On the Render Geometry Settings LOP’s Dicing section, you can now find a new Displacement Style: Bump Added to Displacement. This option greatly improves the quality of the displacement with low Dicing Quality values by blending displacement and bump mapping.

• The camera lens shader’s OpenCV distortion now takes the image’s aspect into account. As a consequence, distortion with non-square renders will look differently.

• Defining an overscan with the Render Settings LOP’s and Karma Render Settings LOP’s Data Window NDC parameter is not always intuitive. A new convenient dropdown lets you choose from several pre-adjusted percentage values.

• To write a material AOV, it was necessary to update each shader definition manually. On the Karma Render Settings LOP’s Image Output ▸ AOVs (Render Vars), you can now define a Global AOV material instead.

• Stencil maps now support UDIMs.

• The new Create Separate Denoised AOVs on the Karma Render Settings LOP creates separate AOVs for the source versions of the source AOVs. New AOVs will have a _denoise suffix. You can find this option in the Image Output ▸ Filters ▸ Image Filters section.

• A new global DCM Exclude Holdouts property in the Karma Render Settings LOP prevents holdouts from generating deep samples.

• Houdini now supports the MotionAPI for scaling motion blur.

• The Karma Uniform Volume Material material definition now uses the Karma Volume VOP shader instead of the Karma Pyro Shader VOP. This means that you no longer need a density field and don’t have to deal with pyro-specific parameters.

• In Karma CPU, you can now use the Karma Hair VOP and Karma Fur VOP shaders with MtlX Mix VOP.

• Karma now supports collection-based trace sets.

• On the Karma tab of every light node you can now find an Improve Volume Sampling (Equiangular MIS) toggle. This option significantly reduces noise when a light source is located within a volume or very close to it. Note that this feature doesn’t work with directional lights or environment lights.

• Geometry lights now support instancing and light filters.

• Geometry lights are now part of the internal light tree structure for more efficient rendering. See Karma Render Settings LOP > Rendering ▸ Sampling ▸ Lights Quality ▸ Light Sampling Mode ▸ Light Tree.

• Volume lights are now also part of the internal light tree structure for more efficient rendering. Rendering times should be significantly shorter, particularly when dealing with a large number of volume lights.

• colorSpace metadata is now added to physical lights to make sure that sun light is correctly interpreted.

• Rectangular area lights now have a option to flip attached maps. For example, on the Light LOP’s Karma tab, you can find the Flip Rectangle Light Texture dropdown menu with options for flipping a map along the X, Y, or XY plane.

• The Geometry Light LOP now supports fixed VDB points.

• With Karma CPU, you can use partially opaque objects as geometry lights. To turn on this features. set the KARMA_GEOLIGHT_PARTIAL_OPACITY environment variable to 1.

Rendering and creating GSplats in Houdini 22 involves many different frameworks: TOPs, COPs, Karma, Solaris, and SOPs. In Solaris/Karma, you can find several fundamental improvements. To get you started, we recommend looking at the new ML Train GSplats from Karma recipe available from the Solaris tab menu.

• Gaussian Splats now render with a noise-free algorithm, ensuring faster and improved results. This, however, does mean that some edge-case AOV and Holdout features may no longer work. You can still reactivate the older noisy/stochastic mode via the KARMA_XPU_GSPLATS_RENDER_MODE environment variable.

• There are also many more improvements:

  • Over 40% faster rendering in the Houdini VK viewport

  • Inciplient support for casting and receiving shadows in the viewport

  • Higher quality, faster and more efficient Karma XPU rendering

  • Realtime playback of animated GSplats

  • Streamlined workflow for rigging and animation

  • Native support for USD’s ParticleField3DGaussianSplat schema

  • Round tripping from SOPs to LOPs using SOP Import LOP

  • Tool set to convert 3D assets to GSplats using Karma and TOPs

  • Support for spherical harmonics

  • Relighting of GSplats

• Cache files for non mipmapped textures will now benefit from a new mode to control handling textures on network file systems. The new default behavior is to create a local texture file when a network texture is detected. This will help to avoid file locking issues on network drives. You can control this mode with the new -network flag in the HOUDINI_TEXTURE_DISK_CACHE environment variable.

• Mipmap computation is now done in linear color space for higher accuracy.

• imaketx now supports writing 16-bit float data to .tx files. This means that you can use .tx files instead of .rat, but .rat files still have some advantages. imaketx will infer the format from the file name.

• Houdini now supports ACES 3.0.