29 March 2023

HtoA 6.2.1.0 is major feature release using Arnold 7.2.1.0.

Installation

• Download Arnold for Houdini
• Follow these installation instructions

Enhancements

• Arnold Render Settings LOP: A new LOP in Solaris allows you to quickly edit Arnold render settings, such as AOVs, cryptomatte, and more. HTOA-1524

• New option "Direct USD Render" in USD Render ROP: A new attribute in the Arnold Tab of the USD Render ROP "Direct USD Render" allows to render directly the USD data to Arnold instead of going through Hydra as husk does. The scene will render as if it was exported to usd and rendered with "kick" - HTOA-2167

• Driver options: Driver parameters like multipart, autocrop, tiling, and append can be set in the Solaris RenderProduct node. HTOA-2078 HTOA-2043

• Arnold RenderVar LOP: A new Solaris node "Arnold Render Vars" allows you to create the Arnold RenderVar AOVs. HTOA-2020

• Flush texture cache: In Houdini 19.5.435 and later the texture cache can be flushed using the new Renderer Commands menu. HTOA-1632

• Distance shader: A new distance shader that uses the distance to the nearest surface to interpolate between near and far color values. (ARNOLD-9361)

• Global light sampling: A new, more efficient sampling technique for lights is available. To enable global light sampling, set Arnold ROP > Properties > Sampling > Advanced > Light Samples to a non-zero value. When enabled, the light sample settings on individual lights are ignored and the overall, global contribution of all lights together is computed using the number of light samples from the Arnold ROP only. In this release, global light sampling does not apply to environment, directional lights, volumes, and GPU rendering. (ARNOLD-12860)

• Disable sky in physical_sky: In addition to the preexisting enable_sun parameter, the physical_sky shader now also has an enable_sky parameter for disabling the sky. This allows, for instance, to have two suns. (ARNOLD-12584)

• Colorspace included in TX filename: AutoTX-generated files now include the original extension and the texture and rendering color spaces in the filename. For example, running AutoTX on my_texture.jpg with an sRGB color space and ACEScg rendering color space will produce: my_texture_sRGB_ACEScg.jpg.tx. Textures that are not supposed to have colorspace changes get the tag raw, such as my_texture_raw.jpg.tx. (ARNOLD-11919)

• Faster node init/update: The node init and update times are now faster. We have seen speedups of up to 20%. (ARNOLD-12870)

• Improved many-core volume scaling: Rendering performance of volumes has been improved on certain many-core machines. The Disney cloud on a dual socket Intel Xeon Linux machine (56 total logical cores) now renders 1.4x faster. (ARNOLD-13004)

• Improved many-core OCIO performance: Rendering performance when using OCIO has been improved. Examples where this speedup might be observed are when using 8-bit textures, textures in a different colorspace to the rendering colorspace, when not using AutoTX, or shading operations that require colorspace transforms. We have seen up to 20% reduction in rendering time on multi-socket systems. (ARNOLD-12912)

• Support up to 1024 CPU cores: AI_MAX_THREADS has been increased from 256 to 1024, which allows Arnold to now create up to 1024 threads for full CPU utilization on machines with up to 1024 cores. (ARNOLD-11015, ARNOLD-12967, ARNOLD-12997)

• Better autobump visibility masking: We can now also disable autobump on camera and shadow rays. These used to be treated as always enabled. For scenes with non-opaque objects, disabling autobump on shadow rays can give up to a 50% speed up if there are many non-opaque objects. This shadow ray optimization should only affect the look when autobump is used to adjust the opacity for shadow ray, which likely is not a common use case. (ARNOLD-8863)

• Instancer light linking: If a light is linked to a shape and both are instanced, then the instancer now preserves this link within instances. This means the first light instance is linked to the first shape instance, the second light instance to the second shape instance and so on. (ARNOLD-12929)

• polymesh.smoothing defaults to true: The default setting for polymesh.smoothing (smoothed normals) is now true across the core and plugins. Previously it was disabled in the core and only some plugins. (ARNOLD-11688)

• Remove warning about using tiled with deep_exr: We no longer warn about using tiled with deep_exr. (ARNOLD-12887)

• Improved triangle intersector: Triangle intersection is now 20% faster and less likely to allow rays to incorrectly slip between triangles, which manifested as holes in a mesh. (ARNOLD-4136)

• Faster loading of OpenVDB volumes in Windows: In Windows, OpenVDB volumes are faster to load, especially on certain many-core CPUs. On one 112-core machine we've seen 4.5x faster loads; other CPUs saw smaller speedups. (ARNOLD-12633)

• Faster instancer initialization: The instancer procedural is now faster on single-socket CPUs. We've seen up to 1.6x faster node initialization on some machines. (ARNOLD-12963)

• alembic.objectpath changed to an array : The alembic procedural parameter objectpath is now an ARRAY type, so multiple object paths can be given to a single alembic procedural. (ARNOLD-12950)

• uv_transform improvements : The uv_transform shader now has a wset parameter, which is the name of a float user data value. A new matrix attribute uvw_matrix returns new coordinates based on the uvw values. If the new attribute uvcoords is linked to a shader, the values returned by that shader override the uv coordinates, at the cost of efficiency because this prevents Arnold from using the correct filtering. (ARNOLD-13049, ARNOLD-13156)

• Motion blur with set_transform: The set_transform operator now has a matrix attribute, that can be animated. This allows set_transform to apply animations and get correct motion blur. (ARNOLD-13068)

• Update OSL : Open Shading Language (OSL) has been updated to version 1.12.9. (ARNOLD-11791)

• New environment variable for external control of autotx: The new environment variable ARNOLD_AUTO_GENERATE_TX overrides the options parameter texture_auto_generate_tx. This environment variable can be either never or when_outdated, which are equivalent to disabling or enabling the global autotx option. (ARNOLD-12875)

• Support field shader on implicit surfaces: OSL scripts can be passed to the field shader of implicit surface. HTOA-1826

• Sidecar manifest in Cryptomatte HDA: The Arnold Cryptomatte LOP now exposes the attribute "sidecar manifest". HTOA-2135, HTOA-1236

• Update Cryptomatte: Cryptomatte has been updated to 1.2.2. (ARNOLD-13101), so sidecar manifests now work with Solaris.

• autotx metadata in tx files: TX files generated with AutoTX now have the metadata autotx 1 added to the TX file. (ARNOLD-13025)

• Ignore motion: A new attribute "ignore motion" is now added to the Render Settings LOP arnold attributes HTOA-2099

• AutoTX Path - A custom path can be defined where TX files will be generated. This parameter is now exposed in HtoA - HTOA-2161

• Update Boost: The Boost library has been updated to 1.81.0. (ARNOLD-12271)

• Update zlib: The zlib library has been updated to 1.2.13. (ARNOLD-13097)

• Update OCIO: OpenColorIO has been Update to 2.2.1. (ARNOLD-12743)

USD Enhancements

• Update Arnold-USD: USD has been updated to 22.11 (ARNOLD-13075, ARNOLD-13099)

• Convert cube, sphere, cylinder, capsule primitives as meshes in the procedural. Geometric primitives are now converted to Hydra meshes instead of Arnold primitives. usd#1318 usd#1451

• Support render delegate products for all Arnold drivers. When rendering using Hydra, with husk for example, the render delegate now uses the RenderProduct drivers. usd#1422

• Arnold Render Products in Hydra: Setting the render product type to "arnold" (instead of the default "raster") will now render the scene with Arnold drivers. This means we support the driver parameters defined in the Arnold tab of the render products. usd#1423

• Instanced skinned meshes: Skinned instances are now rendering in the correct transform and order. usd#1412

• fStop and aperture_size: The procedural and render delegate now support both the fStop and the aperture_size parameters in the camera. usd#1421

• Support combination of half and full precision AOVs in the procedural. The procedural can now render a combination of half- and full- precision aovs. usd#1416

• Always read RenderVar aov:name as an output layer. The RenderVar parameter driver:parameters:aov:name is now used as the output aov layer name. usd#1408

• Support Render Product names: Render Product names are now used as the Arnold output layer names. In exr files, each layer name can now be customized. usd#1408

• Support asset attributes for filenames when no tokens are present. "filename" Arnold attributes are now SdfAssetPaths in USD usd#1163

• Filename attributes as Assets: In Arnold shaders (like the image shader), the filename is now an asset parameter. This allows Arnold to support relative paths in a more consistent way for USD. usd#1418

• MaterialX displacement shaders: MaterialX displacement shaders are now interpreted correctly. usd#1366

• Arnold shader metadata: We now register all Arnold shader metadata in the Sdr registry. Before only the Help and Role metadata were passed to the registry. usd#1390

• AutoTX environment variable: HDARNOLD_auto_generate_tx can be set to override the default AutoTX behaviour in the render delegate. usd#1353

• Driver options in the RenderProduct primitive: It is now possible to set the driver options in the RenderProduct primitive using attribute names prefixed with the driver name in the Arnold namespace. For example arnold:driver_jpeg:quality will set the quality when rendering with the jpeg driver. usd#1346

API Additions

• Enable/disable crash handler for the session: The new function AiSetSystemHandlers() and the environment variable ARNOLD_SYSTEM_HANDLER_MASK have been added, allowing a user to mask Arnold built-in system handlers. The supported masks are listed in AtSystemHandlerMask and currently allow all handlers to be either fully enabled or disabled. (ARNOLD-13014)

• Check if TX file is up to date: The new function AiTextureTxFileNeedsUpdate() returns true if the TX file needs to be regenerated from its source texture. This can happen if the source texture was modified or if Arnold was updated with a newer OpenImageIO library. (ARNOLD-12994)

• Get original texture name for TX file: The new function AiTextureGetTxSourceFileName() returns the name of the texture file used to generate a given TX file. (ARNOLD-13047)

• Load/Read, Write, and Resize image API changes: The Image API functions introduced in 7.1.4 now also take an optional AtParamValueMap so that in the future we can add or change parameters to these functions without breaking the API. Currently there are no parameters these functions expect. Additionally, AiLoadImage() has been deprecated and replaced with the more appropriately named AiReadImage(); functionally they do the same thing. (ARNOLD-12937)

   bool AiReadImage(const char* filename, const uint8_t format, AtImage& image, AtParamValueMap* params = nullptr);
   bool AiWriteImage(const char* filename, const AtImage& image, AtParamValueMap* params = nullptr);
   bool AiResizeImage(const AtImage& inImage, AtImage& outImage, AtParamValueMap* params = nullptr);

• Specify connected inputs in AiMaterialxGetOslShaderCode: The new optional connected_input parameter enables client code to specify input connection on a MaterialX node reference. This is needed for Geometry Property input connections like UV coordinates, to prevent them from being removed from the generated OSL code. (ARNOLD-12712)

• New API to get the name of the TX file generated for a given texture: TX file names now include the color spaces and the extension of the original file, so we added AiTextureGetTxFileName to allow client code to get the exact name of the generated TX file. (ARNOLD-12970)

   AtString AiTextureGetTxFileName(const char* filename, AtString texture_color_space, AtString render_color_space, const AtUniverse* universe);

Incompatible changes

• This version breaks binary compatibility: Shaders, procedurals, and other plugins compiled against Arnold 7.1.x and older are not compatible with this version of Arnold and need to be updated and recompiled.

• Autodesk Network Licensing version : Arnold 7.2 switches to ARNOL_2024 licensing. (ARNOLD-12833)

  • Single-user subscriptions will work with Arnold 7.2. The plugin installers automatically register the new version. If you do not use a plugin, then after you download Arnold, open the Arnold License Manager and click Register.
  • Existing network licenses will not work with Arnold 7.2. Log on to your Autodesk account to generate your new ARNOL_2024 licenses.
  • Autodesk Network License Manager (NLM) servers must be updated to version 11.18.

• Minimum driver requirement raised: The minimum supported Nvidia driver versions are now 512.78 (for Windows) and 510.73.05 (for Linux). (ARNOLD-13169)

• Auto Generate TX and OpenImageIO versioning: Arnold now regenerates tx files only if the OIIO version in Arnold is newer. Using an older Arnold with an older OIIO does not force a regeneration of the tx files. (ARNOLD-12992)

• Auto Generate TX on write-protected folder: When a TX file cannot be generated because the target folder is write protected, the TX file is generated in the system temp folder. (ARNOLD-13039)

• AiLoadImage: AiLoadImage() has been deprecated and replaced with the more appropriately named AiReadImage(); functionally they do the same thing. (ARNOLD-12937)

   inline AI_DEPRECATED bool AiLoadImage(const char* filename, const uint8_t format, AtImage& image)
   {
      return AiReadImage(filename, format, image, nullptr);
   }

• Removed deprecated functions: The following previously deprecated functions have now been removed. (ARNOLD-12938)

   // replace with init() as there is no benefit to specifying an init bound
   void AtBBox::init(float bound);
  
   // replace with AtMutex
   void AiCritSecInit(AtCritSec* cs);
   void AiCritSecInitRecursive(AtCritSec* cs);
   void AiCritSecClose(AtCritSec* cs);
   void AiCritSecEnter(AtCritSec* cs);
   void AiCritSecLeave(AtCritSec* cs);
  
   // Replace with variants that specify the universe or render session
   int AiDeviceSelect(AtDeviceType device_type, const AtArray* device_ids);
   int AiDeviceAutoSelect();
   AtDeviceType AiDeviceGetSelectedType();
   const AtArray* AiDeviceGetSelectedIds(AtDeviceType device_type);
  
   int AiASSWrite(const char* filename, int mask = AI_NODE_ALL, bool open_procs = false, bool binary = true);
   int AiASSWriteWithMetadata(const char* filename, int mask = AI_NODE_ALL, bool open_procs = false, bool binary = true, const AtMetadataStore* mds = NULL);
   int AiASSLoad(const char* filename, int mask = AI_NODE_ALL);
  
   void AiMsgSetLogFileFlags(int flags);
   void AiMsgSetConsoleFlags(int flags);
   int AiMsgGetLogFileFlags();
   int AiMsgGetConsoleFlags();
  
   AtNode* AiNode (const AtString nentry_name, const AtString name = AtString(), const AtNode* parent = NULL);
   AtNode* AiNodeLookUpByName (const AtString name, const AtNode* parent = NULL);
   AtNode* AiNode (const char* nentry_name, const char* name = "", const AtNode* parent = NULL);
   AtNode* AiNodeLookUpByName (const char* name, const AtNode* parent = NULL);
  
   bool AiOpSetTarget(AtNode* node);
   AtNode* AiOpGetTarget();
  
   AtSessionMode AiGetSessionMode();
   void AiRenderAddInteractiveOutput(uint32_t output_index);
   bool AiRenderIsInteractiveOutput(uint32_t output_index);
   bool AiRenderRemoveInteractiveOutput(uint32_t output_index);
   void AiRenderRemoveAllInteractiveOutputs();
   void AiRenderSetInteractiveOutput(uint32_t output_index);
   uint32_t AiRenderGetInteractiveOutput();
  
   bool AiRenderSetHintBool(AtString hint, bool value);
   bool AiRenderSetHintInt(AtString hint, int32_t value);
   bool AiRenderSetHintFlt(AtString hint, float value);
   bool AiRenderSetHintStr(AtString hint, AtString value);
   bool AiRenderSetHintArray(AtString hint, AtArray *value);
   bool AiRenderGetHintBool(AtString hint, bool& value);
   bool AiRenderGetHintInt(AtString hint, int32_t& value);
   bool AiRenderGetHintFlt(AtString hint, float& value);
   bool AiRenderGetHintStr(AtString hint, AtString& value);
   bool AiRenderGetHintArray(AtString hint, const AtArray*& value);
  
   AtRenderErrorCode AiRender(AtRenderMode mode = AI_RENDER_MODE_CAMERA);
   AtRenderErrorCode AiRenderBegin(AtRenderMode mode = AI_RENDER_MODE_CAMERA, AtRenderUpdateCallback update_callback = NULL, void* callback_private_data = NULL);
   AtRenderErrorCode AiRenderEnd();
   AtRenderStatus AiRenderGetStatus();
   void AiRenderInterrupt(AtBlockingCall blocking = AI_NON_BLOCKING);
   void AiRenderAbort(AtBlockingCall blocking = AI_NON_BLOCKING);
   void AiRenderResume();
   void AiRenderRestart();
   bool AiRendering();
  
   bool AiUniverseIsActive();
   bool AiUniverseCacheFlush(int cache_flags);
   AtNode* AiUniverseGetOptions();
   AtNode* AiUniverseGetCamera();
   AtBBox AiUniverseGetSceneBounds();
   AtNodeIterator* AiUniverseGetNodeIterator(unsigned int node_mask);
   AtAOVIterator* AiUniverseGetAOVIterator();

• Removed min_optix_denoiser_sample option: Removed the deprecated and redundant min_optix_denoiser_sample option. (ARNOLD-11714)

• Removed non-functioning kick -of flag: kick -of was removed because it was never able to actually change the output file type. The one thing it could properly do was to output the output file types Arnold can write to, however that functionality can already be reproduced through kick -nodes | grep driver_. (ARNOLD-12857)

• Better autobump visibility masking: Camera ray visibility must now be explicitly set (before, camera ray visibility was enabled regardless of the autobump_visibility setting). Existing scenes that use autobump_visibility may need to enable camera ray visibility. (ARNOLD-8863)

• License Manager log folder changed on Linux: License Manager application and diagnostic logs are now stored under the ~/.autodesk folder on Linux. (ARNOLD-12993)

• kick -nostdin replaced with -stdin: kick no longer automatically reads from stdin, because in the past, waiting for input from stdin caused problems with some tools. If you want kick to read from stdin, use the new -stdin flag. (ARNOLD-6908)

Bug Fixes

• HTOA-2143 - Setting a light texture filename makes a tx even when ar_texture_auto_maketx is off

• HTOA-2156 - Importing material replaces multiple underscores with a single underscore

• HTOA-2095 - Displacement from components or shaders with multiple outputs not working

• HTOA-2094 - Apply scene units to procedural bounding box in the viewport

• ARNOLD-12964 - Rare crash when threads are creating AtStrings at the same time

• ARNOLD-13032 - AiTextureAutoTxFlags not resolving auto color space

• ARNOLD-13115 - Use textures in texture_auto_tx_path even when autotx generation is disabled

• ARNOLD-13197 - Log callbacks ignore maximum number of warnings

• ARNOLD-13201 - Crashes when default universe is null

• ARNOLD-13350 - Set AtNode LocalData pointer to null after node_finish is called

• ARNOLD-12995 - [MaterialX] Support nodes from the MaterialX PBR library in USD

• ARNOLD-13073 - [MaterialX] AiMaterialxGetOslShaderCode fails on ND_switch_color3

• ARNOLD-13074 - [MaterialX] AiMaterialxGetOslShaderCode fails on ND_separate3_color3

• ARNOLD-13107 - Mesh lights occasionally do not render

• ARNOLD-13163 - [GPU] CPU memory leak when rendering multiple frames on the GPU

• usd#1383 - Relative search paths with UDIM and attribute tags are now correctly passed to Arnold

• usd#1380 - Crash when updating a MaterialX shader in Solaris

• usd#1372 - Primitives with an empty purpose attribute are now handled correctly

• usd#1334 - Skip curves with empty radius

• usd#1412 - Fix instance skinned mesh in incorrect position and order.

• usd#1438 - Creating surface models from PBR nodes doesn't work

• usd#1433 - Material binding not handling correctly the different scopes

• usd#1447 - MaterialX Triplanar renders black

• usd#1427 - Motion blur differences between procedural and delegate

• usd#1442 - Velocity motion blur doesn't work if PointInstancer has more than one prototype

• usd#1354 - Vertex mismatch with velocity blur and point normals in Hydra

• usd#1420 - Unify fStop and aperture_size

• usd#1430 - deepexr driver parameters like depth_tolerance are ignored

• usd#1411 - append parameter (for checkpointing renders) is not translated

• usd#1413 - Crash in UsdSkel in the procedural

• usd#1352 - Skinned instances in wrong world position

• usd#1394 - USD procedural renders characters in the wrong positions and order

• usd#1443 - Incorrect number of motion keys with skinned primvar normals and motion blur

System Requirements

• Houdini, Houdini FX, Houdini Indie and Houdini Education
  • 18.5.759
  • 19.0.720
  • 19.5.493
• 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 chip are supported under Rosetta 2 mode.
• GPU rendering works on Windows and Linux only and requires an NVIDIA GPU of the Ada, Ampere, Turing, Volta, Pascal, or Maxwell architecture. We recommend using the 525.89 or higher drivers on Linux and 528.49, or higher on Windows. See Arnold GPU for more information.
• The cache will also need to be re-populated after installing a new Arnold version, updating to a new NVIDIA driver, or changing the hardware configuration of GPUs on the system. More information can be found here.