Show this help.

Print the renderer’s version string.

Print the names of all the rendering properties Karma understands, and their defaults.

Print full information about all the rendering properties Karma understands.

Save the full information about all the rendering properties Karma understands to a file. If the filename is -, writes the information to standard output.

Print all procedural definitions.

Print information about the filters and oracles Karma understands.

Override the Karma rendering engine. Options are xpu or cpu.

Samples per pixel. Default is 128. Specifying this on the command line overrides any render settings in the USD file.

Size of render buckets, in pixels. Default is 128. Specifying this on the command line overrides any render settings in the USD file.

Determines which buckets get rendered first in the image. Options are:

• middle - Render starting from the middle of the image

• top - Render buckets starting at the top of the image

• bottom - Render buckets starting at the bottom of the image

• left - Render buckets starting at the left side of the image

• right - Render buckets starting at the right side of the image

Do not render any lighting (deprecated in favor of --disable-scene-lights).

Ambient occlusion samples (headlight shading). Default is 0.

Ambient occlusion distance cutoff. Default is 1.

Use ‹seed› as the random number seed instead of the frame number.

Dice using the camera at the given prim path. If this is not specified, Karma uses the render camera for dicing.

This option is currently disabled and has no effect.

Specify the default convergence mode for Karma CPU if not provided by a render settings primitive. Values are:

• pathtraced - Maximum of 1 indirect ray per bounce

• distributed (deprecated) - per-component sampling

• variance - Number of indirect rays is calculated based on noise estimates

If this option is given, and no lights exist in the scene, Karma will add a headlight for rendering.

Instead of rendering an image, print information about baking (list of UDIM tiles or the number of images required for ptex texture generation).

The USD scene file to render.

The file used to initialize the asset resolver context for processing the stage.

A string used to initialize the asset resolver context for processing the stage. The option argument should be of the form 'url=string' to configure the resolver responsible for a specific URL prefix, or 'string' to configure the default resolver.

A default variant selection to use for primitives with a variant set but no explicit variant selection for that set. The option argument should be of the form 'set=value1,value2'.

Prints information about the render settings primitives in the scene.

Prints information about the render pass primitives in the scene.

Prints information about the cameras in the scene.

Prints list of all Hydra render delegates available.

Enable GPU (OpenGL/Vulkan/Metal) support for render delegates.

When there are no lights found on the stage, this controls the headlight mode. Possible values are

• none: No headlight will be created

• distant: Create a distant headlight at the camera’s location

• dome: Create a dome headlight

The default value for this option is specified by the HOUDINI_HUSK_DEFAULT_HEADLIGHT environment variable.

Which purpose(s) to render. This can be a comma separated list of purpose tokens. The default is geometry,render.

The geometry complexity to render at. Options are low, medium, high, and veryhigh, or a number between 0 and 8.

Limit stage population to these prims, their descendants and ancestors. To specify multiple paths, use either commas or spaces.

Disable all materials in the scene. This option applies to all render delegates.

Disable all lights in the scene. This option applies to all render delegates.

Overrides the disableMotionBlur render setting, forcing the shutter close time to be equal to the shutter open time. This effectively disables motion blur.

Most render products have raster files as output. Render delegate products are used to represent non-raster products (deep images, checkpoint files, photon maps etc.). This option will disable delegate render products and only generate raster output.

When there are no raster products detected, husk will normally create a “dummy” raster product. This may happen when all products are something other than “raster” products. This dummy raster is largely ignored by husk (setting the product name to husk:null_raster), though some delegates may throw errors without any raster products. This option prevents the creation of the dummy raster product if needed for this special case.

Render using the RenderSettings at the given primitive path. husk will also search for the RenderSettings primitive under /Render.

Multiple render settings primitives can be specified (using a comma or space sparated list) using pattern matching.

Examples:

• --settings /Render/settings1, --settings settings1

  Render using the RenderSettings primitive at /Render/settings1

• --settings *

  Render all render settings in the USD file

• --settings preview1,final*

  Render the preview1 render settings along with all render settings that match final*

Note: Each render settings primitive is rendered independently. If multiple frames or render passes are specified, these will be completed before rendering the next render setting.

Render using the RenderPass at the given primitive path.

Run the given Python script prior to rendering. You can use the stage variable in the script to reference the USD stage being rendered. This script runs after the USD file is loaded, but before reading the settings primitive or rendering. The ‹python_file› argument is parsed into multiple arguments. Care should be taken to properly quote arguments that contain spaces. The hou.frame() function will return the first frame to be rendered. If you need access to the command line, it’s available in the husk_command variable.

Before the render process starts, (i.e. the prerender stage), husk analyzes the render settings primitive and partitions the render products. For example, it’s possible that a single render settings primitive renders two render products that use different cameras. Since the delegate can only render a single camera at a time, husk splits this single render into two separate render tasks (one for each render product). This partitioning is done after the prerender-script.

In contrast to prerender-script, the preframe-script is called before each frame is rendered. However, if the preframe-script tries to change the render camera on a render product, this is impossible since husk has already split the render tasks by the time frames start rendering. Imagine the preframe-script only changed the camera on the second frame in a sequence.

Run the given Python script prior to each frame being rendered. You can use the stage variable in the script to reference the USD stage being rendered. The settings variable contains a dictionary of render settings. This script runs after the USD file is loaded, but before reading the settings primitive or rendering. The ‹python_file› argument is parsed into multiple arguments. Care should be taken to properly quote arguments that contain spaces. The hou.frame() function will return the frame being rendered. The husk command line is accessible using the husk_command variable.

If the preframe script raises a SkipFrame exception, the current frame not be rendered. For example:

Run the given Python script before husk saves a snapshot image. The script should not modify the stage.

Run the given Python script after husk saves a snapshot image. The script should not modify the stage.

Run the given Python script after each frame is rendered. The stage, husk_command and settings variables are available and hou.frame() returns the frame that was just rendered.

Run the given Python script after all frames are rendered. The stage variable is available and hou.frame() returns the last frame rendered.

Control which procedurals should be allowed to contribute to the final USD stage. Valid options are:

• none: no procedurals

• basic: graph procedurals that only generate curves and points

• all: all procedurals (may require Houdini Engine license)

Default is basic.

Save the result of any expanded procedurals

Directory to store expanded procedurals. Default is $HOUDINI_TEMP_DIR.

Enable USD function tracing. The ‹method› determines the reporting method:

• report – Print the time and sample counts for each function.

• timing – Print the time spent in each function.

• chrome – Generate JSON output suitable for viewing in the Chrome tracing format. This option requires the --usd-chrome-file option to specify the log file output.

Note that enabling this option may have a significant impact on performance.

This option both enables USD function tracing (it implies --usd-trace chrome) and also specifies the filename where the JSON tracing information will be saved.

The primitive path of the camera to render from.

Output image file path. This can contain certain local variables:

A comma separated list of filenames can be used to override images when there are multiple render products.

Rendered image width and height, in pixels (e.g. --res 1280 720)

Scale the output image by the given percentage. For example, --res-scale 25 renders the image at 1/4 size, and --res-scale 250 scales the image 2.5× larger.

Pixel aspect ratio (pixel width as fraction of pixel height). Default is 1 (square pixels).

Create any parent directories of the output image if they doesn’t already exist.

Normally, before rendering, husk will verify that render products can be written to disk (optionally creating output directories if the –make-output-path option is specified). With some render products, this may interfere with the rendering process. This option disables any checks or processing that husk does on render products.

Add custom metadata when saving raster products. This is a quick way to add some specific metadata to the output image without having to modify the USD file. If the key is "json", the second argument will be parsed as a JSON dictionary, where each key/value pair will be added as custom metadata. With a single key/value pair, it’s possible to specify more type information for the metadata (using the same rules as described in the HDK documentation for metadata).

Examples:

• --extra-metadata "custom-key" "hello world"

  Stores a string value “hello world” for metadata key “custom-key”

• --extra-metadata "int32 custom-key" "344"

  Stores a 32-bit integer “344” for metadata key “custom-key”

• --extra-metadata "clr3f custom-key" "[1,0.5,0.1]"

  Stores a 32-bit floating point color “[1,0.5,0.1]” for metadata key “custom-key”

• --extrametadata "json" '{"key1":3.14, "key2":"Hello world", "key3":[1.2, 2.3, 4.5]}'

  Stores three pieces of metadata, a number “3.14” for “key1”, a string “Hello world” for “key2” and a vector “[1.2, 2.3, 4.5]” for “key3”.

Start frame number. Default is 1.

Number of frames to render, including the start frame. Default is 1.

Frame increment. Default is 1.

Override the frames-per-second defined on the stage. This value is passed to render delegates as the houdini:fps render setting and can optionally be used when computing velocity motion blur.

Specify a space-separated list of frames to render. This option overrides the other frame options (-n/--frame, -n/--frame-count and -i/--frame-inc). Parsing of this option relies on some heuristics and assumptions. It’s, for example, not possible to define negative frames, because they start with a hyphen (-). This character can be misinterpreted as a command.

Render using an alternate Hydra client.

A list of options that are specific to the render delegate chosen.

Number of threads. 0 means use all processors. -1 uses all processors except one.

Setting this to 0 does a full tear-down of the USD scene and Hydra interface.

Normally, husk uses USD delta operations to make multiple frame rendering more efficient. The delegate is only told about scene data that changes frame-to-frame so it can share work between frames. Using this option will cause the render delegate to be restarted every n frames. For example specifying 1 will cause the render delegate to be restarted every frame. Specifying 3 will use USD deltas for 3 frames, then restart the delegate before rendering the 4th frame. A value of 0 (the default) will never restart the delegate. Since restarting the delegate will cause the scene to be rebuilt, using this option can have significant performance impact and should only be used if truly required.

Save a snapshot of the current state of the rendered image every ‹sec› seconds. -1 means no snapshots. Default is -1.

Overrides the path where the snapshot image should be saved.

Specifies the suffix that’s added to the image filename when saving snapshot images. This defaults to _part. Setting it to an empty string will cause husk to use the final output image name as the snapshot image.

Normally, snapshots are used to show rendering progress and are deleted when the render completes. This option allows you to control this behavior. The possible values are:

• off: Delete snapshot partial images when image is finished rendering.

• number: Save each snapshot as a numbered sequence of files. This allows you to see the progression of snapshots over the render.

Apex COP network to run on the image. This option can occur multiple times and each operation is run in sequence. The slapcomp string specifies a path to the Apex graph, but can also have encoded options. Options are encoded using: path_to_graph?option=value&option2=value2.

Possible options are:

• name: Provide an identifier for this slap-comp operation

• mapinput: Maps an AOV (RenderVar) name to the corresponding Apex graph input name. This option may be specified multiple times.

• mapoutput: Maps an AOV (RenderVar) name to the corresponding Apex graph output name. This option may be specified multiple times.

• filterlist: Indicates that an image Filter List should be applied instead of the default block-based slap comp. In this case, the file should be a CPIO packet that contains the filter list.

For example, if there’s an AOV “C” being rendered, but the Apex Graph has an input “Cin” and an output “Cout”, the argument might look like: --slap-comp path_to_cop.geo?mapinput=Cin:C&mapoutput=Cout=C.

• -1: Use HOUDINI_OIIO_EXR variable.

• 0: Use classic driver.

• 1: Use improved driver.

Use OCIO to transform color when saving images. The values are 1 or 0. When using OCIO, the file rules and RenderVar properties will be used to determine the color space. When OCIO is disabled, this will fallback to Houdini’s intrinsic assumptions about image format color spaces.

Some image formats (OpenEXR) support a data window which only stores pixel data for a part of the overall size of the image. This option lets you automatically trim the data window to only the rectangle in which an AOV (or any of a list of AOVs) has non-zero values.

For example, husk --autocrop C,A will trim to the smallest rectangle containing any non-zero pixels in either the C (color) or A (alpha) AOVs. The default is an empty string, meaning do not autocrop.

You can specify * to mean all AOVs. On the Mac and Linux command line you will probably need to quote the asterisk to prevent the shell from expanding it: husk --autocrop "*".

Note that any pixel data outside the data window is not saved to the image (The data window is an actual cropping of the data, not a display setting).

Because this option only works with “zero” vs “non-zero”, it isn’t useful for values where “clear” is not represented by 0. For example, trimming by color only works with a black background. As another example, it might be useful to crop out “farthest” Z-depth values, but those values are set to the far clipping plane depth, not 0.

This is similar to running iautocrop on the image as a post process.

Add a border of the specified number of pixels around the detected auto-crop region.

Automatically start up an mplay monitor of this render. The monitor can be used to observe progress as the image is rendered. The ‹aovs› specifies a comma separated list of AOVs to be displayed in mplay. For example --mplay-monitor C will only display the color plane (even if the image being written to disk has multiple AOVs). The option --mplay-monitor C,N,diffuse will send the C, N and diffuse planes to mplay for inspection. The selected AOVs must be present in the image being saved to disk to be displayed in the monitor.

If a single hyphen is given for the ‹aovs› (e.g. --mplay-monitor -), then all AOVs will be send to the monitor.

Warning: Closing the monitor will terminate the render.

Specify an scale for any renders to mplay. This includes the monitor or any mplay render products. The value for the ‹scale› argument is currently limited to 10 to 100 percent of the image being rendered to disk. The mplay image will be point-filtered, meaning there will be no blurring of the source pixels. The default is 100.

Disable any rendering to mplay. This option is useful when rendering on headless machines (on a farm).

The number of seconds between updates of the mplay image.

Send mplay renderings to the session specified by the ‹label›.

Specify an image to display in the background of mplay.

Specify a remote host and socket port to connect to for the mplay monitor.

If the ‹gamma› value is greater than 0, set the display gamma in mplay.

Specify a display LUT for mplay.

When turned on, husk will render a single image by rendering multiple tiles in a single process. Once all tiles are rendered, husk stitches them to make the final image. The option uses the Hydra delta operations to efficiently render different tiles without having to reload the scene for each render. This process will not be as fast as untiled rendering, but can have significant memory savings, especially with large numbers of AOVs. You must also specify the --tile-count command line option. Please note that this feature only works on USD files. For example

husk --autotile --tile-count 16 9 myscene.usd

When using -autotile, this specifies the maximum resolution of each tile. Limiting the resolution can make memory usage more consistent even if resolution changes.

This is the location where the temporary images will be saved when using autotiling. This defaults to $HOUDINI_TEMP_DIR.

When using -autotile, the intermediate tile renders are normally removed after the stitching process. This option keeps the source tile images around (which can be useful for debugging).

Husk can render a large image in multiple tiles. This option specifies the number of tiles in the x and y directions. It should be used in conjunction with the --tile-index option.

When using --autotile and the --autotile-res options, it’s possible the number of tiles may be increased if the computed tile resolution is larger than the value for --autotile-res.

When rendering a single image in tiles, this option specifies the index of the tile to be rendered. The index starts at 0. The number of tiles is determined by the --tile-count option.

When rendering a single image in tiles, this option specifies a suffix added to the image filename, expanded using the --tile-index. This option uses the same rules as the -o option (for example _tile%02d). In expansion of the tile index, the F variable represents the tile index, while the N variable is the one-based tile index (starting at 1 instead of 0).

Cancel the render if it takes more than ‹sec› seconds. The default -1 is no time limit.

If the render hits the time limit, don’t save a partial image.

Send standard output to the given file.

On Windows, you can use consolewait or consolenowait instead of a file name. consolewait opens a console window for the output, and you must close the window before the next frame will render. It lets you read fast-moving output but requires you to babysit the window. consolenowait opens a console window and closes it as soon as the frame is done. For slow renders you might still be able to read the output, and it doesn’t require you to click to close the window at every frame.

Send standard error to the given file. This file may be the same as the file specified by --stdout.

Send standard output to the given file, appending to the file rather than replacing.

Send stander error to the given file, appending to the file rather than replacing.

On windows, this option will override the redirection options and open a console to display output. The mode should either be wait or nowait.

Print more or less information while rendering. Default is 2.

Each render delegate can specify a Python script used for verbose feedback in the UsdRenderers.json file. This option allows you to override that script on the command line.

Each render delegate specifies the frequency the verbose callback Python script is invoked. This option allows you to override that interval on the command line.

Specify the resolution for texture maps. This will set the option uinsg the OPENIMAGEIO_IMAGECACHE_OPTIONS and HOUDINI_RAT_MAX_MIP_RES variables.

The licenses that should be enabled when checking for a license for husk. The internal name for the license should be used. Add a , between each license listed.

The licenses that should be disabled when checking for a license for husk. The internal name for the license should be used. Add a , between each license listed.

List the licenses that are available to be checked by husk and the licenses that will be checked by husk.

The license modes that should be skipped when checking for a license for husk. Add , between each mode listed.

• commercial: Skip checking for all commercial licenses.

• education: Skip checking for all education licenses.

• indie: Skip checking for all indie licenses.

• apprentice: Skip checking for all apprentice licenses.

The license modes that should be included when checking for a license for husk. Add , between each mode listed.

• commercial: Include all possible commercial licenses.

• education: Include all possible education licenses.

• indie: Include all possible indie licenses.

• apprentice: Include all possible apprentice licenses.

Use this option to add a delay to when hserver will release the license once the application is no longer using the license.

Use this option to specify the maximum time this application should hold a license seat for. A new license seat is retrieved when the max seat hold occurs. This is a handy option when you want to ensure artists don’t use a given license for longer then they should.

Force an apprentice session.

Force an indie session.

Force an core session.

Allow the app to continue retrying for a license using an exponential backoff. The app will wait indefinitely for a license and therefore can significantly increase the load on the license server. Use very carefully.