Mantra render node

Choosing a target version of mantra allows you to generate an IFD targeted to a specific build of mantra.

The camera object which defines the scene.

The command (i.e. mantra) where the IFD file is sent. This will be disabled if the IFD file is saved to disk.

The location where the IFD file is saved to disk. You must turn on the Disk File checkbox to enable this parameter.

When sending the output to a command, Houdini will normally return control after it is finished writing the IFD. This allows the render process to complete in the background. Turning on this parameter will force Houdini to block until the mantra finishes rendering the frame.

When rendering a frame range, this option is automatically turned on. However, the option is not automatically turned on when rendering in an hscript or python loop construct. Therefore caution must be used or it is possible to end up starting multiple background renders.

If this option is turned on, POP and DOP simulations will be initialized before rendering.

Enabling this checkbox will cause the driver to show up in the viewport menu. By default, SOHO output drivers to not appear in the viewport menu.

The geometry objects in this parameter will be included in the IFD if their display flags are turned on and their display channel is enabled.

Objects in this parameter are added to the IFD regardless of the state of their display. Objects can only be added to the IFD once.

Objects forced to be output as matte objects.

Objects forced to be output at phantom objects.

Objects in this parameter are excluded from the scene, regardless of whether they are selected in the Candidate Objects or Force Objects.

Only lights in this parameter will be included in the IFD. This includes shadow map generation and illumination. If this parameter is set, the candidate, forced, and exclusion parameters are ignored.

Each light in this parameter is added to the IFD if the dimmer channel of the light is not 0. The standard light sets the dimmer channel to 0 when the light is not enabled.

The lights in this parameter are added to the IFD regardless of the value in their dimmer channels.

These lights will be excluded from the scene, even if they are selected in Candidate Lights or Force Lights__.

The fog/atmosphere objects in this parameter are included in the IFD if their display flags are turned on and their display channel is enabled.

If there are no lights in the scene, a headlight is created by default. To disable, turn off this checkbox.

The image or device where the resulting image will be rendered. You can set this value to ip which renders the image in MPlay, or you can save it to an image. The following image types are supported: .pic, .tif, .sgi, .pic.gz, .rat, .jpg, .cin, .rta, .bmp, .tga, .rad, .exr, and .png.

Include $F in the file name to insert the frame number. This is necessary when rendering animation. See expressions in file names for more information.

The image format or device for the output image. If you leave this at the default value of Infer from filename, the image format will be selected based on the file extension (eg. .pic will automatically generate a Houdini format image.)

Specifies the pixel filter used to combine sub-pixel samples to generate the value for the single pixel. The filter is normally specified as a filter type (eg. gauss) followed by an x and y filter width in pixels. To blur the image, increase the filter width.

There are several different pixel filters available.

Controls how transparent samples are combined to produce the color values for individual pixel samples. The sample filter is used to composite transparent surfaces before the pixel filter produces final pixel colors.

The storage type for the primary plane image. The type of quantization used will affect image quality and size. If you need to adjust the image’s dynamic range in compositing, you should normally leave this value at the default of 16-bit floating point.

The white-point of the image used during quantization. Normally you should leave this parameter at the default value of 1 unless you wish to darken or lighten the image.

Normally, sub-pixel samples are filtered using the pixel filter defined on an image plane. When this checkbox is turned on, each sub-pixel is output without any pixel filtering performed.

Normally, the resolution channels on the camera determine the output resolution. Enabling this parameter allows an alternate resolution to be used.

A specific resolution can be specified using this parameter, or alternatively, a fraction of the camera’s resolution.

Allows you to override the camera resolution.

The pixel aspect ratio represents the width of a pixel divided by the height of a pixel. It is not the aspect ratio of the image (which is determined by the resolution of the image). This parameter does not affect rendering, it is only used to change how images are displayed - by stretching the pixels by this factor.

When generating an image, mantra runs the sample filter to composite samples to a single color. Mantra then runs the pixel filter to produce the final color for a pixel. A deep resolver is used to store information about each sample prior to sample filtering. This allows the image resolver to store information about each individual sample before compositing.

The .rat file to generate when the Deep Camera Map resolver is used.

Any number of extra image planes may be generated simultaneously. If the primary output image format supports multiple image planes, the plane name will be used to define the name of the deep raster plane. If the primary output device does not support multiple image planes, each image plane will be output to an individual file, with the name of the plane defining the file name. The formats that support multiple image planes are OpenEXR and Houdini .pic (including the “ip” device).

The name of the image creator. By default uses the current user’s log in name.

A text comment to include in the output file.

The name of the computer where this image was created.

The direction that MPlay displays the rendered the image.

When rendering to MPlay, all Houdini sessions will send the output to the same MPlay flipbook. This can be problematic when running multiple Houdini sessions. The MPlay Label lets you specify a label for the MPlay associated with the output driver. Only renders which match the given label will be sent to that MPlay.

Display gamma for MPlay, from 0.0 to 4.0.

JPEG Quality, integer from 10 to 100.

Type of image compression to use in TIFF files.

Compression type for EXR format images.

See understanding mantra rendering for more information.

The size (in pixels) of the tiles rendered by mantra. Larger tile sizes may consume more memory.

Mantra will assume that surfaces become opaque when processing many layers of transparent surfaces, rendering with volume primitives, or when the cumulative opacity exceeds this limit. This prevents additional rendering behind opaque layers.

When enabled, automatically set the thread count to the number of CPUs of the rendering machine.

When Use Max Processors is disabled, set the number of threads used for rendering.

Controls the type of ray tracing accelerator used by mantra. A ray tracing accelerator is a spatial data structure used to optimize the performance of ray intersection tests against complex geometry.

Change the memory/performance tradeoff used when constructing KD-Tree acceleration data structures. Values larger than 1 will cause mantra to use proportionally more memory and take longer to optimize the tree in an attempt to make ray tracing faster. Smaller values will cause mantra to use proportionally less memory and take less time to optimize the tree, while possibly compromising ray tracing performance. The default value of 1 will try to balance the amount of memory used by ray tracing data structures with the amount of memory used by geometry.

The number of megabytes used for the geometry cache.

The number of megabytes used for texture caching. This includes all texture caching.

The name of the object to be rendered in UV space. Mantra is able to render an object in UV space rather than 3D space.

The name of the attribute used in UV un-wrapping.

Perform hidden surface removal. When hidden surface removal is disabled, all surfaces in the camera’s frustum will be rendered, regardless of whether they are occluded. This can impact render time significantly.

Renders an image from the viewing camera. Sometimes, it is useful to skip this render, for example, when rendering shadow maps.

Enable or disable shadow map generation. Each light also has its own controls to determine whether shadow maps will be generated.

Enable or disable environment map generation. Each object can be set up to generate an environment map of all the other objects in the scene.

Enable or disable photon map generation.

Enabling this checkbox will expand any variables in OTL paths, breaking the dependency on Houdini environment variables, but possibly making the IFD less portable.

Mantra is able to load the shader directly from the OTL when Houdini uses a shader defined in an OTL. When shaders are built using VOPs, the shader must be embedded in the IFD. Enabling this option will force Houdini to embed the shaders defined by OTLs.

This option makes the IFD more self-contained so that machines which don’t have the OTL installed (or a different version of the OTL) are able to evaluate the shaders correctly.

However, if you have complicated shaders, embedding them will bloat the size of the IFD significantly.

Mantra will render with depth of field. The parameters controlling depth of field may be found on the camera object.

Mantra will render the image using motion blur. The shutter parameter on the camera determines the duration of the shutter, specified as a fraction of the frame. The Xform Time Samples and Geo Time Samples parameters should be used in motion blur renders to control how motion blur is computed. By default, only transformation motion blur with 2 segments will be computed - meaning that animated SOPs will not produce blur in the render. To enable motion blur for moving geometry, it’s necessary to increase the Geo Time Samples.

Enable or disable raytrace motion blur for micropolygon rendering and photon map generation. By default, raytrace motion blur is disabled. This setting has no effect on the ray tracing rendering engines.

This parameter automatically adjusts the shading quality for objects which are significantly blurred. When an object is blurred heavily, whether due to depth of field or motion blur, increasing the motion factor will automatically decrease the shading quality.

Motion factor reduces shading quality using the following formula:

    new shading quality = shading quality / max(pixels of motion * (1/16), 1)
    

Objects traveling more than 16 pixels within the frame will have their shading quality reduced by the above factor. For example, an object blurred over 32 pixels with a shading quality of 1 will have the quality reduced to 0.5. You should not use very large values for this parameter. Values between 0 and 1 are reasonable.

The number of transformation blur motion samples. Each object (unless the parameter exists on the object) will have this many transforms output over the shutter duration. Increasing this number will result in smoother sub-frame motion, at a small memory and compute expense. Any number of segments may be specified, though the default of 2 is often adequate unless significant nonlinear motion occurs within the shutter time for a frame.

The number of deformation blur motion samples. Each object (unless the parameter exists on the object) will have this many copies of the geometry included in the IFD. When an object is deforming it is necessary to increase this parameter to a value of 2 to see motion blurred geometry. Any number of segments may be specified, though a value of 2 is often adequate unless significant nonlinear motion occurs within the shutter time for a frame.

This option has no effect on objects which use velocity blur, since velocity blur is linear by nature.

The type of motion blur. You can choose either a trailing, centered, or leading blur.

The terminology refers to time, that is “leading” blur will open the shutter ahead of the current frame.

This checkbox controls whether mantra computes motion blur for direct visibility. If this checkbox is disabled, mantra will render without motion blur but still compute motion blurred positions so that you can use getBlurP() in shaders to export motion vectors.

The number of samples which are filtered to compute the color for each pixel. Increasing the samples will improve motion blur and depth of field quality. Two sample values are specified for x and y, with the total number of pixel samples is determined by multiplying these values together. Normally both values are set to the same amount, with common pixel sampling settings being 3×3, 8×8, and 16×16.

When using the ray-tracing engines, each ray is shaded independently. Very large values for pixel samples in this case may significantly increase rendering time. However, often large pixel sample values are necessary with the Physically Based Rendering engine to eliminate noise.

A floating point value which adds noise to pixel sampling patterns. A value of 1 will fully randomize pixel sampling patterns, while a value of 0 turns of pixel jitter resulting in stairstep artifacts when too few pixel samples are used. Jitter only applies to pixel antialiasing and does not apply to motion blur or depth of field sampling, which are always randomized.

This property will “lock” the sampling patterns from frame-to-frame. This minimizes the buzzing caused by noise when rendering animations. The noise is still present, but is more consistent frame-to-frame.

When the micro-polygon rendering engine is used, each vertex of each micro-polygon is shaded one time. When ray-tracing is invoked in shading, mantra is able to automatically anti-alias the ray-tracing by oversampling. When variance anti-aliasing is used, there will be at least the minimum rays sent for each shade and at most the maximum number of rays. Mantra uses variance analysis on the shading results to determine the actual number of rays.

If variance anti-aliasing is disabled, the minimum number of rays will be sent for each shading sample. When primary ray-tracing engines are used, these parameters are ignored and anti-aliasing is done using the pixel samples.

The minimum number of ray-tracing samples used in variance anti-aliasing.

For Physically Based Rendering, this parameter can also be used to boost the number of samples taken for each shading point without increasing the pixel samples.

The maximum number of ray-tracing samples used when variance anti-aliasing.

The noise threshold used for ray variance antialiasing. Lower values produce less noisy images.

The distance in world space between volume samples when rendering volume primitives. Larger step sizes can be used to decrease quality and improve performance, and smaller step sizes should be used to increase quality. This parameter should be set based on the scale of your scene. For example, if your volume primitive is 100 units wide, the volume step sizes should be increased to 1 or 10 to accommodate the scale of your scene.

A factor to proportionally decrease the sampling quality for volume shadows. Smaller values will cause mantra to use a larger step size for shadow rays. A value of 1 will produce equal quality for shadow rays and shading rays.

An integer value that controls initialization of pixel sampling patterns. Different random seeds will produce different pixel sampling patterns.

Limit the number of specular bounces for physically based rendering. Increasing this limit will produce more accurate rendering of scenes that have many inter-reflections (such as scenes containing glass or fluids).

The maximum refraction bounces.

Limit the number of diffuse bounces. Diffuse bounces usually contribute to the majority of global illumination in a scene, so increasing the diffuse limit will produce more accurate global illumination.

This only works with PBR and with the GI Light object in raytrace/micropolygon because diffuse bounces need to be traced by a shader, and when you're rendering with micropolygon/raytrace, most shaders do not calculate diffuse bounces themselves. The PBR shader and the GI Light both include a computation of diffuse lighting.

The maximum volume bounces allowed in PBR mode.

Global raytracing bias to be used for PBR rendering, specified in world space units. Increase the raytracing bias only if doing so eliminates rendering artifacts in your render. For really small scenes (1 unit in size), it is sometimes necessary to decrease the raytracing bias.

When biases are used in VEX shaders, the bias can either be performed along the ray direction or along the surface normal. When this checkbox is turned on, biasing will be along the surface normal.

Sampling color space for variance antialiasing. Setting this to Gamma 2.2 will cause darker parts of the image to receive more samples.

Controls how PBR deals with rays that reach the ray tracing limit, such as the reflect or refract limit.

When micro-polygon rendering, shading normally occurs at micro-polygon vertices at the beginning of the frame. Enabling this checkbox causes the vertex colors to be Gouraud shaded to determine the color for a sample.

The shader to use for physically based rendering. If no shader is specified, the default VEX Pathtracer shader is used. Normally you should not need to assign a shader for this parameter unless you are a shader writer and need to make adjustments to the PBR shading algorithm.

The shader to use for photon map generation. If no shader is specified, the default VEX Photon Tracer shader is used. Normally you should not need to assign a shader for this parameter unless you are a shader writer and need to make adjustments to the PBR photon tracing algorithm.

The type of path tracing to perform in PBR mode.

When performing shading, mantra places no limits on values which may be returned. However, when performing Physically Based Rendering, it’s possible to get very large values for some rays. These extrema will show cause color spikes, which cannot be smoothed out without sending huge numbers of rays. The color limit is used to clamp the value of the Cf variable to avoid these spikes.

Enables a minimum amount of secondary ray tracing even when the surface bsdf reflects only a small amount of light. Normally, when mantra encounters a surface that reflects only 10% of the incoming light, ray tracing will be optimized by sending 10x fewer secondary rays, potentially leading to unwanted noise in the image. Increasing this parameter will ensure that the specified proportion of rays are traced as a minimum even for surfaces that have a low reflectivity.

Increasing this value will cause more information to be printed out during rendering. To see render time and memory information, set the verbosity level to 1. To see more detailed information about the render, set this parameter to 3. Larger values print out progressively more information.

A percentage complete value is printed out as tiles are finished. This is in the style expected by Pixar’s Alfred render queue.

This parameter specifies a python callback which can be called at the completion of each tile rendered. There is a built-in mantra module which allows information to be queried. There is a single function available in the mantra module. The property function allows querying of any global rendering property as well as some other special properties. The result of the property call is always a list of values.

A global multiplier on all shading rates in the scene. Each object has a shadingrate property.

Mantra allows a separate shadingrate when ray-tracing is performed (compared with scanline rendering). This parameter is a global multiplier on all ray-tracing shading rates in the scene. Each object has a rayshadingrate property.

When primitives are rendered in mantra, they are split into smaller primitives if they are too big to be rendered. The primitives are measured to determine if they are too big using the measurer.

See Micropolygon Measuring above.

Saves binary geometry in the IFD. If this option is turned off, ASCII geometry is saved in the IFD. Binary is much more efficient. ASCII is readable.

Controls whether geometry groups are saved to the IFD. Groups can require a significant amount of storage and are normally unused during rendering, so leaving this option disabled will improve IFD generation time and reduce file size.

This option enables the irradiance cache, which can significantly improve the performance of the irradiance and occlusion VEX function calls.

The maximum error tolerance between samples in the irradiance map. Normally you should only decrease this value from the default of 0.1 if there are artifacts in the render.

The maximum screen space between irradiance samples. Lowering this value will force more samples to be computed, creating a more accurate representation of the irradiance information.

In some cases, you can get a very dense clustering of irradiance samples in the cache. This parameter prevents the clustering by ensuring that there are at least this many pixels between samples. Clustering usually occurs between non-smooth intersections between different primitives.

The file to store the irradiance cache. If multiple objects specify the same file, the cache file will contain samples from all objects.

The Read/Write mode for the file.

This command is run before any IFDs are generated. It is only run once per render.

This command is run before each IFD is generated.

This command is run after each IFD is generated.

This command is run one time, after all IFDs have been generated.

Orientation of curve/point primitives. Curves and points will be oriented so that their normals point in the direction of the orient vector attribute.

(velocity) Used for velocity motion blur computations.

Default attribute for the -u command-line option.

Shader overrides (per primitive).

Controls width of curve/point primitives (see below).

Not used by mantra.