Render Settings: Legacy mental ray tabs

For Maya 2016 mental ray Render Settings, see the following topics:

The mental ray tabs consists of five tabs: Passes tab, Features tab, Quality tab, Indirect Lighting tab, and Options tab.

For information on other render settings, see Render Settings window.

Passes tab

Use this tab to do the following:

create, edit and delete a render pass
create, edit and delete a render pass set. A render pass set is a group of render passes.
create, edit and delete a render pass contribution map
manage the list of render passes for the current layer
manage the list of render passes for each of the pass contribution maps in your current layer

Note:

See Multi-render passes for more information regarding render passes.

Render Passes

Use the and buttons to add a new render pass or a new render pass set to the current layer.

New Pass: Click to open the Create Render Passes window. See Create Render Passes window for more information.
New Set: Click to create a new render pass set.
Edit: Click to open the Attribute Editor for the selected render pass or render pass set. Alternatively, you can double-click a pass or pass set in the Scene Passes, Associated Passes, or Passes Used by Contribution Map sections to open its Attribute Editor.
Delete: Deletes the selected render pass(es).
Pass Set Relationship Editor: Click to open the Relationship Editor. You can use the Relationship Editor to manage the membership of each pass set.
Scene Passes: Lists all the render passes and render pass sets that are available to be assigned to the current layer. After a render pass or render pass set is assigned to the render layer, it no longer belongs to the Scene Passes list. In other words, this list shows only passes that not assigned to the current render layer.
Associated Passes: Use the and buttons to associate and de-associate render passes from the current active render layer.

Note:

You can also right-click a render pass/pass set to set it as renderable; or, create an override for the pass/pass to make it renderable.

Associated Pass Contribution Map: Use this section to manage the render passes for each pass contribution map. Select the pass contribution map that you want to manage from the drop-down list. See Render Layer Editor and Render pass contribution maps for more information regarding pass contribution maps.
New pass contribution map: Click to create a new render pass contribution map.
Edit pass contribution map: Click to open the Attribute Editor for the selected pass contribution map.
Delete pass contribution map: Delete the selected pass contribution map.
Passes Used by Contribution Map: Use the up and down arrow buttons to manage the list of passes for the current pass contribution map.

Note:

Any pass in the Associated Passes section that is not affiliated with a pass contribution map is generated for the layer.

Pre-Compositing

Pre-Compositing Template for <layer>: Use this section for pre-compositing to Composite. Each render layer can have an optional Composite pre-compositing template file associated with it. This pre-compositing file (enter a file path and file name) is used when Render > Export Pre-Compositing is selected. If this field is left empty, a composite is constructed without a template and provides only the passes that have been rendered. The user must then wire the render passes to create a composite. A default template is provided which covers all render passes available in Maya. See Exporting the multi-render passes for compositing in Composite for more information.
Use MasterLayer’s Template: Use this attribute to mark whether the layer's precompTemplate value is the same as that of the masterLayer's.

Features tab

Render Mode

Select one of the following options:

Normal: Render all features set in the Render Settings window.
Final Gathering Only: Performs final gather computation only. Use this mode to create or update an final gather map file associated with the render layer. It can also be used to create a final gather map file for each frame or for specific frames. Once the final gather map has been created, the user can switch back to Normal mode, and reuse the pre-computed final gather map files for final gather rendering.
Shadow Map Only: Each light can, optionally, enable shadow maps (normal or detailed). During a normal render, shadow maps are computed "on demand" for the portion of the shadow map required. The Shadow Map Only mode is designed to pre-compute shadow map files without triggering any other rendering process. This can greatly help rendering speed since the pre-computed shadow maps can be used by several other machines on the render farm. A shadow map is dependent on light position and object position; if any of these elements are to be moved, the shadow map is most likely to require a recomputation. This mode does not detect which lights needs to be updated, but instead systematically re-computes all lights with shadow map statements.
Light Map Only: Light maps are used for two purposes: custom baking (requires a special shading network for each object) and for subsurface scattering. The Light Map Only mode is most useful for forcing all lights maps to be computed without triggering any other rendering process. By doing so, this mode allows you to precompute light map based shading such as sub-surface scattering. The user can precompute all light maps and subsurface scattering maps as pre-render passes. Rendering on the farm is therefore much more efficient, since the sub-surface scattering maps have already been computed.

Secondary Effects

Select one of the following options:

Raytracing: Turns raytracing on or off. Enables reflections and refractions.

Note: Raytracing is always enabled with mental ray. You can only disable raytracing when you use Legacy Rasterizer Mode (scanline).
Global Illumination: Turns global illumination on or off.
Caustics: Turns caustics on or off.
Importons: Turns importons on or off. Importons can be used when raytracing is enabled and in combination with global illumination, caustics and irradiance particles. See Importons for more information regarding importons.
Final Gathering: Turns final gather on or off.
Irradiance Particles: Turns irradiance particles on or off. Enabling irradiance particles also enables importons by default. If final gathering is enabled, then irradiance particles is disabled.
Ambient Occlusion: Turns ambient occlusion on or off.

Note:
You must enable Ambient Occlusion if you are creating an ambient occlusion pass. See Multi-render passes for more information.
Shadows: Turns shadows on or off.

Motion Blur

Select one of the following options:

Off: Turns motion blur off.
No Deformation: No Deformation only considers the position of objects at the Shutter beginning and end point (open and close points). It performs object-based interpolation and is fast but limited.
Full: Full is slower to render, but gives true (that is, exact) motion blur results. Each deformed surface is being translated "per vertex", instead of per object transform.

Extra Features

Faces

Determines whether to render double-sided or single-sided for the entire scene.

Front: Only front-facing (that is, the side whose normal vectors face away from) are rendered.
Back: Only back-facing are rendered.
Both: Works especially well if volume effects are used.

Turn these options off, to globally disable the following features in your scene:

Geometry Shaders
Light Maps
Lens Shaders
Displacement Shaders
Displacement Pre-sample
Enables pre-computation of displacement maps to find optimal bounding boxes.
Volume Shaders

Volume Samples: This setting specifies the default value for the number of volume samples for any volume effects in Maya shaders. The default value is 1.

Note:
When Auto Volume is turned on, Raytracing is automatically enabled and greyed out.

Auto Volume
If enabled, mental ray manages volume levels and the volume stack automatically.
Output Shaders
Photon Auto Volume
Merge Surfaces
Render Fur/Hair

Contours

The following attributes control the location and characteristics of contour line rendering.

Enable Contour Rendering: Turn on or off (default) contour rendering.
Hide Source: When turned on, only the contour is visible (that is, the object that causes the contour invisible).
Flood Color: When Hide Source is turned on, this is the conlour used to flood or fill the entire frame as the background color before rendering the contour. In other words, this is the color onto which the contours caused by Hide Source are drawn.
Over-Sample: Improves the quality by processing at N times larger than sampling down to the correct size. If this value is set to 2, the contours are processed at twice the resolution, so the quality (anti-aliasing mostly) will be approximately twice as good.
Filter Type: The filter type used when downsampling contours to image resolution.
Filter Support: The filter support as (fractional) number of pixels.

Draw By Property Difference

Options in the detection section let you define the locations at which mental ray for Maya detects and draws contour lines.

Around silhouette (coverage): Draw contour lines based on pixel coverage (where rendering samples detect objects are present) based on a pixel being covered by the object.
Around all poly faces: Draw contour lines around each poly face on an object.
Around coplanar faces: Draw contour lines between different normals.
Between different instances: Draw contour lines between different instances.
Between different materials: Draw contour lines between primitives with different materials.
Between different labels: Draw contour lines between different labels (these are not the same as character labels).
Around render tessellation: Draw contour lines between different primitives. (Enabling this in effect draws tessellations.)
Front vs. back face contours: Draw contour lines between, if the sign of the dot product of the normal vector and the view vector differs from one sample to the other.

Draw By Sample Contrast

Enable Color Contrast: Turns on or off (default) the color contrast setting.
Color Contrast: Draw contour lines between pixels that have a color difference that is larger than the set value.
Enable Depth Contrast: Turns on or off (default) the depth contrast setting.
Depth Contrast: Draw contour lines between pixels whose depth difference (in camera space) is larger than the set value.
Enable Distance Contrast: Turns on or off (default) the distance contrast setting.
Distance Contrast: Draw contour lines between pixels whose distance is larger than the set value.
Enable Normal Contrast: Turns on or off (default) the normal contrast setting.
Normal Contrast: Draw contour lines between pixels whose normal difference is larger than the set value. (Normal difference is measured in degrees.)
Enable UV Contours: Turns on or off (default) the UV contour setting.
UV Contours: Draws contour at every Uth and Vth isoline of the primary UV space.

Custom Shaders

You can connect mental ray for Maya base contour store and contrast shaders here. Any shaders connected here override the integrated contour rendering feature.

Quality tab

Sampling

Sampling Mode

Select among the following sampling modes: Unified Sampling, Legacy Rasterizer Mode, and Legacy Sampling Mode.

The unified sampling options provide a simplified user interface for the primary sampling settings. These methods use enhanced sampling strategies in mental ray to avoid typical artifacts like visible regular patterns. When Unified Sampling is enabled, you only need a set of few controls to adjust the primary sampling. In particular, a single Quality slider is available.

Unified sampling unifies spatial and temporal sampling, and each ray has its own space and time sample. Tuning a render with motion blur is now easier, and performance gains can be expected with motion blur and depth-of-field rendering.

Note: Different functionalities are available in this tab depending on the Sampling Mode that you have selected.

Tip: Contour rendering is not supported with Unified Sampling mode. Use Legacy Sampling Mode instead for contour rendering.

Unified Sampling

Quality

Use this slider to adaptively control image quality. This is the main control for adjusting image quality when unified sampling is used.

Progressive Mode

Progressive rendering begins with a lower sampling rate and then progressively refines the number of samples towards the final result. It is recommended that you set this option to IPR Only to use progressive sampling with IPR.

You can also enable this feature by enabling IPR > IPR Quality > IPR Progressive Mode in the Render View window.

Sampling Optimization

Min Samples / Max Samples: Minimum and maximum samples per pixel. If you no longer notice any improvement after tweaking the Quality setting, increase Max Samples. If you have enabled the Diagnose Samples option, and your mr_diagnostic_buffer_samples reflect that you have reached the Max Samples in some areas where the render still seems noisy, increase the Max Samples.
Error Cutoff: Stop sampling pixels when error falls below this threshold. Do not tweak this attribute unless absolutely necessary.
Quality As Color: Per channel control over sampling quality. Useful for tuning renders but should be considered an expert option; do not use unless you must.

Legacy Rasterizer Mode

Shading Samples: Shading rate per spatial sample.
Samples: Number of samples per pixel for anti-aliasing.

Legacy Sampling Mode

Select one of the following options:

Fixed Sampling

Use a fixed number of samples per pixel when processing an image.

Adaptive Sampling

The number of samples used per pixel varies depending on the contrast of your scene. The Max Sample Level and Min Sample Level will not differ by more than 2.

Custom Sampling

The number of samples used per pixel varies depending on the contrast of your scene.

Custom Sampling allows you to tune the Min Sample Level and Max Sample Level independently, while retaining true adaptive sampling (unless the min and max sample level are set to the same value). Custom Sampling also allows you to set the min and max sample level to greater than two. In general, the min and max sample level should not differ by more than 3.

Min Sample Level

This is the guaranteed minimum number of samples per pixel used when processing an image. Based on Anti-aliasing Contrast settings, mental ray for Maya will increase these samples as needed.

You can enter a negative value for this field. Instead of super sampling, infra-sampling is performed, where 1 pixel is sampled for each N pixels, depending on your Min Sample Level.

Max Sample Level

This is the absolute maximum number of samples per pixel used when processing an image.

Number of Samples

Indicates the actual number of samples to be calculated based on the current settings.

Note: When Adaptive Sampling is selected, the Max Sample Level and Min Sample Level will not differ by more than 2. This is the recommended setting.

For advanced users: if you wish to override the default recommended setting for per object sampling, choose Custom Sampling.

Anti-aliasing Contrast

Use the slider to set your contrast threshold. Lowering this value increases sampling (up to the Max Sample Level), which results in higher quality but longer processing time. Depending on the actual contrast of the image, you may not be able to get better results (that is, results are limited by the amount of contrast).

Note:

This attribute was previously named Contrast Threshold, with one slider for an RGB value and one slider for an alpha value. The single slider sets RGBA to the same value under the hood. If you want different values for RGBA, you can do this through scripting or through the miDefaultOptions node.

Sample Options

Filter

This is processing performed on the results of the sampling to blend pixels into a coherent entity. Black and white = noisy. Filtering looks at neighboring info and unifies the two.

It is better to apply filtering in the renderer, since there is more information (samples) to work with and filtering can offer better control when applied to samples than as a post-process and applied to pixels.

Box (default)

The fastest way to get relatively good results.

Note:

See mental ray for Maya reference documentation, Scene Description Language section, Scene Entities sub-section, Options page for more information on various filter methods.

Triangle

More processor intensive than box, but offers even better results. Samples at the center of the pixel will have the highest contribution weight. As samples move further away from the center of the pixel, their contribution weight fall off linearly. This causes samples and details at the center of the pixel to be more "present" in the final computed pixel in the framebuffer.

Gauss

Produces the best results, but is the slowest to render. Gauss uses a curved fall-off for sample contributions. Almost all samples at the center of the pixel have virtually the same contribution weight, but rapidly falloff (smooth). Gauss requires a minimum filter size of 3 and this filter mode is known to make the images more blurry.

Mitchell, Lanczos

Mitchell (clip) and Lanczos (clip) are alternatives to Gaussian that offers slight variations in contrast (tends to increase). Mitchell increases less than Lanczos.

Because “plain” Lanczos and Mitchell may produce negative values the new filter types are “clipped” variants to ensure positive values. The filtered result samples are clipped to the min/max range of input samples. The final pixel in the image will therefore not contain any out-of-range values _produced by the filter_, as might be the case for regular Mitchell and Lanczos filters.

These filters tends to sharpen the final computed pixels. Therefore, if you want to enhance the image details, choose Mitchell and Lanczos as your filter method.

Filter Size

Controls the filter size used to interpolate each pixel in the rendered image. The larger the value, the more info from neighboring pixels. The larger the value, the more the image is blurred. The value should be at least 1,1.

Filter size and filter mode are disabled whenever the Min Sample Level and Max Sample Level settings are below -1 0. mental ray for Maya does not filter when rendering using a Min Sample Level and Max Sample Level below these threshold values.

Jitter

Reduces artifacts by introducing systematic variations into sample locations. Without jittering, samples are taken at the corners of pixels or subpixels; jittering displaces the samples by an amount determined by lighting analysis.

Sample Lock

Locks the location in which you sample within pixels. When turned on, this option ensures that the sub-pixel samples occur at the same location within in each pixel, which is important to help eliminate noise and flickering results. Turn it off only if you get sampling problems, such as moire patterns.

Note: This option is disabled if you select the Unified Sampling Sampling Mode. If you notice film grain noise, increase the Quality slider.

Diagnose Samples

Shows how spatial supersamples were placed in the rendered image, by producing a grayscale image signifying sample density. This is useful when tuning the level and the contrast threshold for spatial supersampling. More diagnostic attributes are available in the Diagnostics section under the Options tab.

Diagnose Samples for Unified Sampling: If you have selected Unified Sampling as your Sampling Mode, you can select this option to generate a diagnostic.exr file that includes the following channels:

mr_diagnostic_buffer: a beauty pass of your render
mr_diagnostic_buffer_error: demonstrates the variance in irradiance among all samples. A lower variance implies convergence.
mr_diagnostic_buffer_samples: demonstrates the number of samples for each pixel
mr_diagnostic_buffer_time: demonstrates the amount of time required to render each pixel

In the Render View window, select File > Load Render Pass > Diagnose samples to load the diagnostic.exr in imf_disp. The diagnostic.exr file is also located in the renderData\mentalray folder of your project directory.

Rasterizer

Rasterizer Transparency

If set to a positive value, then the transparency compositing for the rasterizer ends at the specified depth. This can be used to tune performance for scenes where it is known that the main color information is provided by the first few depth layers.

It also allows you to limit the amount of hair/fur being rendered. You should exercise caution as you lower the transparency depth, since it is possible for the final pixel intensity to shift as less surfaces are contributing to the final pixel.

Raytracing

Raytracing

Select raytracing as the secondary renderer so that, when the primary renderer (scanline or rasterizeror raytracing) detects that refractions or reflections are needed, it will switch to raytracing only mode. Raytracing can produce the most physically accurate reflections, refractions, shadows, global illumination, caustics and final gather.

Reflections

The maximum number of times a ray can be reflected off reflective surfaces.

Motion Blur

Select one of the following options:

Off: Turns motion blur off.
No Deformation: No Deformation only considers the position of objects at the Shutter beginning and end point (open and close points). It performs object-based interpolation and is fast but limited.
Full: Full is slower to render, but gives true (that is, exact) motion blur results. Each deformed surface is being translated "per vertex", instead of per object transform. Select this method for motion blur of objects being deformed by animation, such as jiggling arms and jello-like motions, where the vertices are moving and jiggling as the animation occurs.

Motion Steps

See also diagram in Shutter Open, Shutter Close.

If motion blurring is enabled, mental ray can create motion paths from motion transforms, much like multiple motion vectors on vertices can create motion paths.

This option specifies how many motion path segments should be created for all motion transforms in the scene. The number must be in the range 1 to 15. The default is 1.

Time Samples

This option is only applicable to the Legacy Rasterizer Mode and the Legacy Sampling Mode.

Primary control for the quality of motion blur. This attribute defines the number of temporal shading samples per spatial sample. Increasing the number of samples gives better quality of motion blur. However, increasing the number of samples also increases rendering times.

Spatial samples are samples taken from the perspective of the xy plane of the image. For still images, spatial samples are affected by the Anti-Aliasing Quality controls. At each spatial sample location, mental ray can take a number of temporal samples. Temporal samples are samples that are taken at different times between shutter open and close and add an extra dimension, time, to the x and y dimensions of spatial samples. Each spatial sample at location x,y is a combination of multiple temporal samples, each taken at a different time.

Motion Blur Optimization

Motion Blur By

This is a multiplier used to amplify the motion blur effect. Increasing this value reduces the realistic results achieved, but may produce an enhanced effect if that’s what you want to achieve.

The higher the value, the longer the time interval used in the motion blur’s computation.

Displace Motion Factor

Controls the fine displacement quality according to the amount of visual motion. Allows a reduction in tessellation density as objects move faster. This option is compatible with all renderer types: raytracing, scanline and rasterizer. For moving polygonal objects with displacement, this attribute automatically controls the quality of displacement according to the amount of visual motion.

For fast moving objects, images with comparable visual quality may require fewer displacement tessellation details as compared to static or slow moving objects. Although it is also possible to tweak displacement approximation on a per-object basis, this process is tedious and is rarely done in practice. Per-object granularity may also not be fine enough to accommodate objects with different amount of motion in different parts.

This attribute provides an automatic way of adjusting the displacement quality according to the amount of motion for a given object part. For view-dependent fine poly displacement, the adaptive subdivision checks for the motion length in screen space. The measured motion length is used to modify the use of the approximation constant. Geometry is reduced only in the areas of the object with strong motion.

This attribute modifies the amount of geometry reduction as compared to the static case. A value of 0 disables the feature. 1 is the default and higher values provide more reduction. The simplification of geometry has an effect on motion of approximately 16 pixels. For slower motion, higher values should be used. For example, the factor value of 8 reduces geometry in areas with objects moving at the speed of 2 pixels per frame.

Motion Quality Factor

When you use the rasterizer with motion blur, you must decide between using higher values, which yield better quality, and lower values, which yield a faster render. Setting this attribute to values larger than 0.0 automatically lowers shading samples for fast-moving objects, at a rate proportional to the magnitude of the setting and the speed of the instance in screen-space. You should exercise caution when tuning this value, but 1.0 (the default) provides a good starting point. A value of 0.0 disables the setting.

Keyframe Location

The motion offset when calculating motion blur.

Shadows

Shadow Method

Select one of the following options:

Disabled

Select this option to turn shadows off. This option is automatically selected if shadows are disabled under the Quality tab.

Simple (Unsorted Occluders)

Enables simple shadows, which are standard for the provided libraries. This is the most efficient of the three shadow modes.

If shadows overlap because multiple objects obscure the light source, the order in which these objects are considered (and their shadow shaders are called) is undefined. If one object completely obscures the light, no other obscuring objects are considered.

Note:

When you use Simple shadows, you are limited to only one shadow ray per light source. Therefore, if you want to create soft shadows, which require more than one shadow ray to be cast, you should use Segments shadows instead.

Sorted (Presorted Occluders)

Enables shadow sorting.

Similar to Simple, it ensures that the shadow shaders of obscuring objects are called in the correct order, object closest to the illuminated point first. This mode is slightly slower but allows custom shadow shaders to record information about obscuring objects. If no such custom shader is used, this mode offers no advantage over simple shadow on.

Segments (Traced Occluders)

Like Sorted, the shadow shaders are called in order. Shadow rays are traced much like regular rays, passing from one obscuring object to the next, from the light source to the illuminated point; each such ray is a shadow segment.

Use this mode if you want volume effects (like fluids, particles, fur and smoke) to cast shadows.

This mode requires support from the shadow shader, which must use the mi_trace_shadow_seg function to cast the next shadow ray segment.

For more information about the mi_trace_shadow_seg node, see mental ray Manual.

Note:

The Shadow Method is set to Simple by default. Simple shadows are not compatible with volume effects such as fluids, volume fur, particles and volume shaders and therefore may not render shadow volume effects correctly.

Shadow Linking

You can reduce the rendering time required for your scene by linking lights with surfaces so that only the specified surfaces are included in the calculation of shadows (shadow linking) or illumination (light linking) by a given light.

Note:

You can also use render pass contribution maps for light and shadow linking. For instance, if you have a scene with 150 lights associated to your render layers, and you create a simple pass contribution map where only one light is associated with it, only that light is evaluated by the shader. For more information regarding render pass contribution maps, see Multi-render passes

Use the drop-down list to select one of the three choices available with this option:

On
Obeys Light Linking
Off

The shadows in your scene can obey only one of light linking or shadow linking and not both. Therefore, you must decide whether to incorporate light linking or shadow linking in your scene and make your selection from the drop-down list accordingly.

You can also render part of your scene using the default settings (instead of obeying the links that you have created). Select Off so that all links that you have established using shadow linking or light linking are ignored.

The default is set to Obeys Light Linking.

See Shadow linking for more information regarding shadow linking. See Light linking for more information regarding light linking.

Shadow Maps

Format

Select one of the following options:

Shadow Maps Disabled

Select this option to turn off shadow maps.

Regular (OpenGL Accelerated)

Causes mental ray for Maya to use OpenGL acceleration (if available with your graphics hardware) when rendering shadow maps.

The same limitations apply as mentioned with the Scanline option. Shadow maps rendered with this option contain slightly different information from those generated with the regular (On) algorithm, and the soft areas of shadows tend to be smaller. Some areas may incorrectly be determined to not be in shadow.

When OpenGL rendering of shadow maps is enabled, only the local workstation (master) participates since the computation cost of the map is so small that the networking overhead would be more costly.

Detail / Regular

The Detail shadow map option is a combination of features from regular shadow maps and raytraced shadows, meaning that it collects more information about shadow-casting objects.

Unlike the regular shadow map, a detail shadow map also takes into account surface and lighting properties, such as transparency. Detail shadow maps store a list of depth values together with the light transmission coefficients at each depth. This provides similar quality shadows as raytraced shadows, but at processing times similar to depth map shadows.

Detail shadow maps may require more time to calculate because they compute and store more per-pixel information.

Note:

Detail shadow maps are more sensitive to the Softness attribute (in the Attribute Editor, Shadow Map Attributes section for the light shape node). A large Softness value results in a penumbra spread well beyond the shadow area.

Rebuild Mode

Determines whether all shadow maps are recomputed.

Reuse Existing Maps

Shadow maps are loaded from files or reused from previously rendered frames if possible. Otherwise, created from new.

Rebuild All and Overwrite

Shadow maps are recomputed and the existing points are overwritten by the recomputed points. This is the default option.

Rebuild All and Merge

Specifies that shadow maps should be loaded from files, if available. The default shadow map calculations are still performed and the existing points are overwritten by the recomputed points, but only if the new points are closer to the light source.

This option is useful for building shadow maps for use in multi-pass rendering because it allows shadow maps from a previous render pass to be reused for the current pass. Only shadow map changes are recalculated, not the entire shadow map.

Motion Blur Shadow Maps

Determines whether shadow maps should be motion blurred so that moving objects cast shadows along the path of motion.

Turning this option off (default is on) can cause shadow maps to render slightly faster.

Note:

Since shadow maps do not deal with transparent objects and motion blurring introduces a form of transparency at the edges, shadow map shadows can appear too large in the direction of motion if the object moves quickly.

Rasterizer Pixel Samples

Controls the anti-aliasing quality when computing shadow maps with the rasterizer. This attribute sets the samples collect option for shadow map rendering to the specified value. A value of 0 uses the rasterizer default for shadow map rendering.

Framebuffer

Data Type

Select the kind of information the framebuffer contains.

Each image file format supports one or more data types. In addition, each file format is associated with a default data type. If you select a data type that is not supported by the file format that you have chosen, then mental ray for Maya will use the default data type associated with the file format instead. For example, if you have chosen to save the image as a tif file, but you have selected RGBA (Half) 4x16 Bit as your data type, then mental ray for Maya will render as an 8-bit RGBA (the default data type) instead, since RGBA (Half) 4x16 Bit is not supported by the tif format. For a list of data types supported by each file format, refer to the mental ray documentation.

Note:

When creating multi-render passes, this is the MasterBeauty pass.

Gamma

Use this setting to apply gamma correction to rendered color pixels to compensate for output devices with a nonlinear color response. Inverse gamma is applied to textures as well. The reverse correction is applied to all quantized texture images.

All R, G, B, and alpha component values are raised to 1overgamma_factor. The default gamma factor is 1.0, which turns gamma correction off.

Note:

The behavior of the Gamma correction attribute for the Maya software renderer is the reverse of that of the Gamma attribute for the mental ray renderer. mental ray Gamma is basically an un-gamma, where it removes Gamma correction to ensure it is in linear space prior to computing raytracing. Therefore, mental ray Gamma is not a display gamma, but an ungamma feature. For the Maya Software renderer, a higher gamma value lightens the mid-tones of the image. For the mental ray renderer, a higher gamma value darkens the mid-tones of the image.

Colorclip

Controls how colors are clipped into a valid range [0, 1] before being written to a non-floating point frame buffer or file.

In all modes, the RGB components are clipped as specified by the desaturate option. The RGB and alpha modes ensure that the resulting color is a valid premultiplied color.

Clipping occurs only in 8-bit integer and 16-bit integer frame buffers. if you are using float and half-float, no clipping occurs.

RGB:RGB is first clipped to [0, 1] and alpha subsequently to [max(R, G, B), 1]. Use RGB if the alpha channel is considered less important than preserving the RGB color and intensity.
Alpha: Alpha is first clipped to [0, 1] and RGB subsequently to [0, A]. Alpha mode is intended for alpha compositing, where the alpha channel is more important than the absolute color value to preserve correct transparencies.
Raw: RGB and A are both clipped to [0, 1] independently of each other. Use Raw mode only if no layering based on alpha is going to take place. This mode turns Premultiply on, so use it with care because shaders might receive colors that cannot be composited in standard ways.

Interpolate Samples

This option causes mental ray for Maya to interpolate sample values between two known pixel sample values. If interpolation is turned off, the last sample value in each pixel is stored, and pixels without samples get a copy of a neighboring pixel. When this option is turned on, the resulting image has a higher quality, but takes more time to process.

This option is on by default.

Desaturate

If a color is output to a frame buffer that does not have 32-bit (floating-point) and half-float (16-bit float) precision, and its RGB components are outside the range [0, max], mental ray clips the color to this legal range.

If desaturation is turned off (on by default), the individual components are simply clipped into range. Otherwise, mental ray tries to maintain the brightness of the color by moving it towards the grayscale axis of the color cube, until the RGB components are in the legal range. The max is determined by the colorclip mode.

Premultiply

If this option is on (default), premultiplication takes place (see Premultiplied images).

If on, mental ray for Maya renders objects so that they are not anti-aliased against the background. For example, a pixel on the edge of an object is not mixed with the background color. (In TIFF terms, Maya generates unassociated alpha.)

The premultiply off option instructs mental ray to always store colors unpremultiplied into frame buffers and files. When this option is off, mental ray does not premultiply the textures or the output frame buffers. This option is ignored if the colorclip raw mode is in effect.

Dither

mental ray for Maya supports 8, 16, or 32 bits per color component. In some cases, 8 bits per pixel, as supported by all popular picture file formats, can cause visible banding when the floating-point color values calculated by the material shader are quantized to the 8-bit values used in the picture file. Dithering mitigates the problem by introducing noise into the pixel such that the round-off errors are evened out. Note that this can cause run-length encoded picture files to be larger than without dithering. Dithering is turned off by default.

Rasterizer use opacity

When using the rasterizer, enabling this setting enforces transparency/opacity compositing to be performed on all color user framebuffers (in other words, non-primary color buffers) regardless of the individual setting on the framebuffer. By default, only the primary color frame buffer and explicitly marked user buffers are considered for rasterizer compositing. This option may be used in combination with the user framebuffer interface in Maya 2008 or below.

You must enable this option to ensure that the rasterizer renders passes that are identical to those rendered using raytracing/scanline (primary renderer).

Contrast All Buffers

Use in conjunction with the multi-render passes feature. See Multi-render passes for more information.

Occasionally, you may notice aliasing on the edges of your render passes that does not exist in your overall beauty pass. Mental Ray's adaptive sampling algorithm analyzes the local contrast in the rendered image to determine whether or not a given image region requires finer sampling. This is a performance optimization technique that allows mental ray to sample the image more coarsely in regions of uniform color, and finely in areas that contain detail, such as object edges and intricate textures. Therefore, this algorithm may yield aliasing in render passes that contain high contrast detail in areas where the master beauty pass is smooth. Enable this option so that the adaptive sampling algorithm analyzes the contrast in all color frame buffers being rendered, rather than for just the master beauty pass.

The render may be faster when the option is turned off, at the risk of compromising image quality when the multi-render pass workflow is used.

Legacy Options

Scanline

Scanline rendering is faster for smaller scenes. When rendering large and complex scenes, use the rasterizer or raytracer as the primary renderer instead. Scanline requires extra memory requirements during rendering which raytracer and rasterizer do not.

Note:

When generating a motion vector file, mental ray performs the calculations differently depending on whether scanline is on or off. When scanline is on, both the camera motion and object motion are used to compute the motion vector file. Otherwise, if scanline is off, only the object motion is used for the calculations.

Samples Per Object

Enable min/max sample overrides for objects.

Shutter Open, Shutter Close

Defines the point in time at which the shutter opens and closes within the frame interval to control motion blurring.

The defaults for Shutter Open and Shutter Close are 0.0 and 1.0, respectively. If the values for Shutter Open and Shutter Close are equal, motion blurring is disabled; if Shutter Close is greater than Shutter Open, motion blurring is enabled. The normal range is (0, 1), which uses the full length of the motion vectors or motion vector paths. It can be useful to set both to 0.5, which disables motion blurring but renders with an offset of one half frame, which allows bidirectional post-blurring in an output shader.

Note:

The mental ray for Maya renderer draws its shutter setting from this section in the Render Settings window, unlike the Maya renderer (for which the shutter setting is on the camera).

Acceleration

Acceleration Method

Select one of the following options:

Regular BSP: The BSP (binary space partitioning) acceleration method recursively subdivides 3D space into a nested set of voxels, small boxes with triangles in them. It is efficient, but careful attention should be given to the size and depth parameters, which can have a large impact on speed and memory usage.
Large BSP: Use for very large scenes. It breaks the scene into small data blocks that do not need to be stored in memory at all times. However, it may increase rendering time.
BSP2: This is the default. BSP2 stands for Binary Space Partition, second generation. It enables a new BSP raytracing acceleration designed to cope with large scenes. BSP2 does not need to adjust any attributes like the old generation BSP and Large BSP, which frees the user from the tedious tuning required to achieve optimal rendering performance. BSP2 can be used whenever instances are heavily used in a scene. If you choose the grid acceleration method, which is no longer exposed in mental ray for Maya but is still accessible from the mental ray standalone command line, mental ray defaults back to BSP2 internally.

BSP Size

Determines the maximum number of triangles in one bsp voxel. If you decrease this number, you will have more voxels and a heavier bsp structure, resulting in higher memory usage and better performance.

BSP Depth

Determines the maximum number of voxel subdivisions.

Separate Shadow Bsp

This option enables mental ray for Maya to use a secondary Bsp tree for objects that have low-detail shadow stand-ins to improve performance.

Diagnose Bsp

Shows the cost of creating and traversing the BSP tree used for raytracing. Both the depth and the leaf size can be visualized. If the diagnostic image shows that mental ray has been operating near the limit in large parts of the image (indicated by red or white pixels), this helps tuning the BSP parameters in the options block.

Indirect Lighting tab

Environment

Image Based Lighting

When you click the Create button, a new IBL node is created, replacing any currently connected node. (Though multiple IBL environments can exist in a scene, only one can be used at a time.)

For more information, see Image-based lighting (sky-like illumination) and also Render infinitely distant (sky-like) illumination and reflection.

For descriptions of the attributes in the IBL node, see Image based lighting node attributes.

Physical Sun and Sky

When you click the Create button, a network containing the mia_physicalsky, mia physicalsun, and directionalLight is created. Maya automatically connects all the necessary attributes from the four nodes for you. This network is connected to all existing renderable cameras.

The Attribute Editor for the mia_physicalsky shader also contains two buttons that allow you to edit your camera connections. Choose between Update Camera Connections and Remove Camera Connections.

For more information, see Simulating the sun and sky and Adding sun and sky to your scene .

Note:

Image based lighting and physical sun and sky are not designed to work together at the same time. It is therefore recommended that you either use one or the other.

Global Illumination

Global Illumination

Use this to turn on or off (default) Global illumination, a process that allows for indirect lighting and effects like color bleeding. The default is off.

Global illumination is computed only for light sources for which photon emission is enabled.

Accuracy

Change the number of photons used to compute the local intensity of global illumination. The default number is 64; larger numbers make the global illumination smoother but increase render time.

Scale

Use this setting to control the influence of indirect illumination effects for global illumination. You can select a color with the Color Chooser or use the slider to set the Scale value. Scale is off by default.

Radius

Controls the maximum distance at which mental ray for Maya considers photons for global illumination. When left at 0 (the default), mental ray for Maya calculates an appropriate amount of radius, based on the bounding box size of the scene. If the result is too noisy, increasing this value (to 1 to start, then by small increments up to 2) decreases noise but gives a more blurry result. To reduce the blur, you must increase the number of global illumination photons (Global illumination Accuracy) emitted by the light source.

Merge Distance

The photons within the specified world-space distance are merged. For scenes with uneven photon distribution, this attribute can greatly reduce the size of your photon map.

Caustics

Caustics

Turn caustics on or off (default). Caustics are produced only by light sources for which photon emission is enabled. The material shader (which must have a non-zero diffuse component) that receives the caustics must be set to receive caustics.

Accuracy

Controls the number of photons used to estimate the caustic brightness. The default is 64. Higher settings (up to 100 to start, tested in small increments) larger numbers make the caustic smoother.

Scale

Use this setting to control the influence of indirect illumination effects for caustics. You can select a color with the Color Chooser or use the slider to set the Scale value. Scale is off by default.

Radius

Controls the maximum distance at which mental ray for Maya considers photons for caustics. When left at 0 (the default), mental ray for Maya calculates an appropriate amount of radius, based on the bounding box size of the scene. If the result is too noisy, increasing this value (to 1 to start, then by small increments up to 2) decreases noise but gives a more blurry result. To reduce the blur, you must increase the number of caustic photons (Accuracy) emitted by the light source.

Merge Distance

The caustic photons within the specified world-space distance are merged. This attribute can greatly reduce the size of your caustic photon map.

Caustic Filter Type

Controls the sharpness of the caustics.

Filtering increases the weight of photons that are close to the point of interest, and reduces the amount of blur at the edges of a caustic.

Box: Generally makes caustics looks sharper. It is faster, but less precise.
Cone Generally makes caustics looks smoother. It is more precise, but slower.
Gauss

Caustic Filter Kernel

The bigger the kernel, the softer the caustic.

Photon Tracing

Photon Reflections

Use this to limit the number of times a photon will reflect in a scene (after the first bounce, which is taken care of by direct illumination). It works in conjunction with Max Photon Depth.

Photon Refractions

Use this to limit the number of times a photon will refract in a scene (after the first bounce, which is taken care of by direct illumination). It works in conjunction with Max Photon Depth.

Max Photon Depth

Use this to limit the number of times a photon will bounce around (reflect or refract) after the first bounce (which is taken care of by direct illumination) in a scene.

Default is 5, but correct value depends on how many surfaces the photon must go through or bounce off of before hitting a diffuse surface to stop. For example, if a photon goes through 6 transparent surfaces, the default 5 would produce incorrect results. After the depth trace limit has been met, photons are not re-emitted and instead are absorbed.

Custom shaders may override these values.

Photon Map

Rebuild Photon Map

If a filename is specified for the photon map (in Photon Map File), the map is loaded and used (providing the file exists). If this option is turned on, any existing file will be ignored, and the photon map will be recomputed and an existing file will be overwritten. The default is off. In other words, if you want to build a map, turn this option on; if not, turn this option off and specify the file to be used in Photon Map File.

Photon Map File

Specify the photon map file that mental ray for Maya should use as the current photon map. It will be loaded and used without computing a new photon map. If the photon map file does not exist, one will be created and saved.

Enable Map Visualizer

Causes Maya to create a visualization of stored photon and final gather maps. The visualization appears in the scene view immediately after rendering is complete. See Final Gathering Map.

Direct Illumination Shadow Effects

This should be turned ON if you use transparent shadows with Global illumination and, or caustics.

The attribute does not affect performance if the scene does not use any shadow effects (for example, material shaders setting shadow attenuation).

By default, mental ray automatically detects if additional shadow shaders should be exported to render shadow effects such as attenuation and colored shadows.

For global illumination, this procedure is disabled by default, since shadowing should already result from indirect lighting and caustics with photons. But the shadow attenuation effect through transparent objects is not easily achievable with global illumination.

This option enables shadow effects detection, and produces shadow effects from direct lights in addition to indirect shadowing from photons.

Diagnose photon

Select one of the following options:

Density: When photon maps are used, select this option to replace all material shaders in the scene with an internal shader that produces a false-color rendering of the photon density.
Irradiance: When photon maps are used, select this option to replace all material shaders in the scene with an internal shader that produces a false-color rendering of the average of the red, green and blue irradiance components.

Photon density

Shows a false color rendering of photon density on all materials. This is useful when tuning the number of photons to trace in a scene, and to select the optimum accuracy settings for estimation of global illumination or caustics. It also works well in combination with the Grid Mode.

Photon Volume

Photon Auto Volume: Check this option to enable a volume-tracking mode that keeps track of the volumes that the camera is in and takes over inside/outside decisions. This option helps render a camera passing through volumes such as light cones from streetlights.
Accuracy: Controls how the photon map is used to estimate the intensity of caustics or global illumination within a participating medium. It applies to photon volume shaders, which compute light patterns in 3D space, such as volume caustics created by focused shafts of light cast by objects acting as lenses.
Radius: Controls the maximum distance at which mental ray for Maya considers photons for a participating medium.
Merge Distance: The volume photons within the specified world-space distance are merged. For scenes with uneven photon distribution, this attribute can reduce the size of your volume photon map.

Importons

Importons: Enable this option to turn on importon emission.Importons are particles similar to photons. However, they are shot from the camera and traverse the scene in the opposite order. Instead of energy, they hold a quality which is an importance of the contribution to the final image. The information from importons is used by the kernel for distribution of rendering efforts according to the final contribution to the rendered image, in other words, importance-driven sampling. Importons are thus a foundation for new view-dependent indirect illumination techniques.
Density: Number of importons shot from the camera per pixel. The minimum value for this attribute is 0.02, which is approximately 1 importon per 50 pixels. The default and recommended value is 1. Lower values speed up importon emission but could also decrease final image quality.
Merge Distance: The importons within the specified world-space distance are merged. The default value is 0, which means that merging is disabled.
Max Depth: Controls the diffusion of importons in the scene. If set to zero, importons will not scatter on the diffuse bounces. The default is zero. In some cases you may need to use more than a single diffuse bounce, for example, when you are using final gather, or when the Traverse option is disabled.
Traverse: Enable this attribute so that importons are not blocked by even completely opaque geometry. Instead, they are stored for all intersections with geometry on the ray from the camera to infinity. This leads to a significantly higher number of importons stored in the scene. However, it removes the discontinuity in the distribution of the importons originated from the visibility to the camera function.

Final Gathering

Final Gathering

Use this to turn Final Gathering for global illumination on or off. The default is off. Final gathering is a different means of calculating indirect illumination. For more information, see Final gather.

Accuracy

Controls how many rays are shot in each final gathering step to compute the indirect illumination. The default is 100 per sample point. Higher values are required for final renders. Increasing the value reduces noise but also increases the rendering time.

Note: When the Final Gather Accuracy is changed, the Primary Final Gather File is always ignored and new Final Gather rays are emitted.

You can see, in the Output window, when this happens:

RCFG 0.2 info: finalgMap/test1:final gather options differ from ones currently used, content ignored.
RCFG 0.2 info: overwriting final gather file "finalgMap/test1".

Point Density

Controls the number of final gather points to be computed, performing the full and time-consuming final gather tracing.

Point Interpolation

The number of final gather points to be considered for interpolation at a shading sample during rendering. Higher values smooth the final gathering result at little cost.

Primary Diffuse Scale

The Scale value allows you to easily control the intensity and color of the final gather contribution on a global scene level. You can use the Color Chooser or use the slider to set the Scale value.

Secondary Diffuse Scale

Scale the contribution of final gathering secondary bounce to the final render result.

Secondary Diffuse Bounces

Use this attribute to set multiple diffuse bounces for final gathering. This option controls whether indirect diffuse lighting contributes to final gather, up to a sum of the Final Gather Reflection and Final Gather Refraction values. Use this attribute to add more light and color bleeding to your final gather results. Also, use this option to prevent unnatural darkening of corners in your scene. The higher the value, the longer the final gather computation process.

Final Gathering Map

Rebuild

If this is on (default), any previously generated Final Gather file is ignored and all final gather points are recomputed. See Primary Final Gather File for more information about the file.

If this file is off, Final Gather is forced to use the results from a previous Final Gather render. Existing final gather points are not recalculated, and any new final gather points are appended to the existing file.

The Freeze option stops any new data from being written to the final gather file. It is useful to reduce light flickering in your animation. See Troubleshoot final gather causes flicker.

Tip:

If you are rendering out a still image and are not changing the Final Gather settings, turn this attribute off to save rendering time.
If you are rendering out a camera animation sequence, you may be able to use previous frames’ Final Gather results (that is, you can turn this attribute off), depending on how the irradiance changes during the animation. However, if objects in the scene move, this option must be on.

Primary Final Gather File

This is the file that stores the Final Gather results that mental ray for Maya can use for irradiance lookups. You can reuse Final Gather results from a frame rendered earlier, or from a previous scene render:

If no filename is specified and Rebuild is turned on, rendered results are placed in a default file.
If you specify previously non-existent filename, the rendered results are placed in the file with that name.
If you specify an existing filename here, and Rebuild is turned on, the specified file is overwritten with the newly rendered Final Gather results.
If you specify an existing filename here, and Rebuild is turned off, the newly rendered results are appended to the existing file. (This means that the file may grow without bounds.)

Secondary Final Gather File

You can provide several final gather map files as lookup map files for the rendering. You can therefore use the final gather map rendered from different cameras and combine the lookups at render time. Also, a secondary final gather map can be used to lookup final gather map files from different frames. For example, you can make the primary final gather map file lookup the final gather map file for the current frame T, and the secondary final gather map file to look up other final gather map files from other frames such as T+1 and T-1 (assuming that you have pre-generated a final gather map file using the Render ModeFinal Gathering Only).

Enable Map Visualizer

Causes Maya to create a visualization of stored photon and final gather maps. The visualization appears in the scene view immediately after rendering is complete. See Photon Map.

Preview Final Gather Tiles

If turned on, this setting lets you see tiles as they render. That is, you can see the image as it renders.

Precompute Photon Lookup

This option (which also turns on Final Gather) causes photon tracing to compute and store an estimate of the local irradiance at every photon location. This means that far fewer final gathering points are required because the photon map carried a good approximation of the irradiance in the scene—mental ray for Maya can estimate irradiance with a single lookup, instead of many photons. In this case, photon tracing takes longer than before and requires slightly more memory, but rendering is faster.

Diagnose finalgather

This option allows you to render by final gathering points in green for initial raster-space, and in red for render-time final gathering points. This is useful in fine tuning final gather settings to distinguish between view dependant and non-view dependant results to better distribute final gather points. This option is off by default.

Final Gather Quality

Filter

Use this to control how Final Gather uses a speckle elimination filter to prevent samples with extreme brightness from skewing the overall energy stored in a Final Gather sampling region.

Neighboring samples are filtered so that extreme values are discarded in the filter size. By default, the filter size is 1. Setting this to 0 disables speckle elimination, which can add speckles but will better converge towards the correct total image brightness for extremely low accuracy settings. Size values greater than 1 eliminate more speckles and soften sample contrasts. Sizes greater than 4 or so are not normally useful.

Falloff Start, Falloff Stop

Use these settings to limit the reach of indirect light for Final Gather (but not photons). If no object is found within a distance of start, the ray defaults to the environment color. Objects farther away than stop from the illuminated point will not cast light. An extra advantage is that this speeds up final gather computation, since final gather does not evaluate all visible surfaces, but only the ones visible within defined ranges.

Normal Tolerance

Use this attribute to specify the maximum angle, in degrees, up to which a final gather point normal may deviate from the surface normal for the final gather point to be considered for interpolation.

A lower value may increase rendering times while a higher value decreases rendering times.

The valid range is 0 to 90 degrees and the default is 25.842.

Final Gather Tracing

Reflections

Use this to limit the number of times subrays will reflect in a scene. It works in conjunction with Max Trace Depth.

Refractions

Use this to limit the number of times subrays will refract in a scene. It works in conjunction with Max Trace Depth.

Max Trace Depth

Use this option to specify the number of subrays for the final gather render. The default is 0, which means that indirect illumination computed by final gathering cannot pass through glass or bounce off mirrors, for example. A depth of 1 would allow a single refraction or reflection. Typically, a depth greater than 2 is not necessary.

Final Gather Mode

Automatic: This is the default mode. It uses Accuracy and Point Density, but not the Max Radius and Min Radius, to control final gathering sampling and interpolation.
Optimize for Animations : Enable multi-frame final gather mode to reduce flickering in animation. The accuracy of the render may suffer in some parts of the animation because a constant number of final gather points is used for the entire animation and therefore some parts of the scene may not contain the sufficient number of points.

This option sets the final gather mode to multiframe. See Final gather for more information.
No FG Caching: Select this option to disable final gather caching completely and always perform the full and accurate final gather computation. This option may reduce rendering time for simple scenes but increases rendering time for complex scenes.
Use Radius Quality Control: Switch back to the first generation final gather algorithm where the radius is used to control final gathering sampling and interpolation.

Min Radius, Max Radius

Max Radius and Min Radius control the size of the sampling region within which Final Gather rays search for irradiance information from other surfaces.

With the default values, Maya calculates values that seem appropriate based on scene dimensions to speed up the render, but this calculation doesn’t allow for complex geometry. Generally, enter a value that is 10% of scene’s overall dimension for the Max Radius, then enter 10% of that for Min Radius. Make further adjustments based on scene geometry detail, how the geometry is arranged in the scene, and how the render looks. For example, use these settings to achieve better diffuse detailing in nooks and crannies in your scene.

View (Radii in Pixel Size)

This option causes the Min Radius and Max Radius of final gather rays to be calculated in pixel size, rather than in object space. This allows you to set the visual quality in pixel size, without knowing the object or scene bounds.

Irradiance Particles

Irradiance particles is a global illumination technique which is sometimes superior to final gather and/or photon mapping in terms of image quality, usability and performance.

Before rendering, importons are shot to the scene from the camera. Data regarding their hit positions with information on the amount of direct (and possibly indirect) illumination coming at their position (hence the name "irradiance particles") are combined into a map. One or more passes of indirect illumination can be computed.

During rendering, Irradiance Particles are used to estimate the irradiance for every shading point. If only direct illumination is collected for irradiance particles, then this is equivalent to one bounce of indirect lighting. Irradiance can also be interpolated from precomputed values at particle positions.

Irradiance Particles cannot be used in combination with global illumination and final gathering However, Irradiance Particles are compatible with caustic photons.

Irradiance Particles

Select to enable irradiance particles.

Rays

The number of rays shot while estimating the irradiance. This attribute is similar to the number of rays used for final gathering, but instead, it specifies the maximum number of rays and delivers better quality than final gathering does with the same number of rays. The minimum value is 2 and the default value is 256.

Indirect Passes

The number of possible passes of indirect lighting. If >0, then a sequence of passes is computed to collect the irradiance coming from multiple indirect illumination bounces and irradiance Particles would have both direct illumination and indirect illumination information. If =0, then Irradiance Particles will only have direct illumination information. The default value is 0.

Scale

Global scale factor applied to the intensity of the irradiance during rendering. Values other than the default do not lead to a physically correct rendering but are useful for artistic purposes. The value is expanded to a color having the same R, G and B components. The default value is 1.0.

Interpolate

Controls the use of interpolation. Choose among no interpolation, interpolating always, or interpolate only for secondary rays (that is, no interpolation for eye rays and interpolation for reflections, retractions, and so forth). The default is always.

Interpoints

The number of irradiance particles used for the lookup interpolation. The default value is 64.

Environment

Enables the use of the environment maps for irradiance computation. A separate particle map is built for the environment (if an environment shader is present) and used during rendering for image based lighting.

Env. Rays

The number of rays used for the computation of irradiance coming from the environment map. The default for Env. Rays is the same as the number of Rays set for the Irradiance Particles option. For outdoor scenes, the default works fine, but increase this value for indoor scenes.

Env. Scale

Global scale factor applied to the irradiance contribution of the environment. The scaling factor is relative because it applies to the environment irradiance only. The environment irradiance can be further scaled (multiplicatively) if the user specifies a global scaling factor with the Scale option. The default value 1.

Rebuild

If enabled, mental ray for Maya computes the irradiance particle map even if a file with the specified name already exists. If disabled, mental ray reads the irradiance particle map from the specified file, or, it reuses the irradiance particle map that comes from the previous frame rendered.

Disabling this feature is useful for animations, which are flicker-free. However, the irradiance particle map may lose quality if the objects and camera are moving, so this is only recommended for fly-throughs. In addition, since the particle map is view dependent, inaccuracies may show up on the frame image borders. This option is enabled by default.

Map File

Specifies the map file for the irradiance particle map.

If the specified file exists, mental ray for Maya tries to read the irradiance particle map from this file (unless Rebuild is enabled). If the irradiance particle map is not successfully read from the file, mental ray for Maya computes it and saves it to a file with the given name. This behavior is consistent with the photon maps option.

Ambient Occlusion

Ambient Occlusion: Enable ambient occlusion support. Computation is performed on demand of shaders only.

Note:
You must enable ambient occlusion if you are creating an ambient occlusion render pass. See Multi-render passes for more information regarding render passes.
Rays: Number of ambient occlusion rays used for the computation of each ambient occlusion value. mental ray shaders using ambient occlusion API can override this value internally.
Caching: Control creation of the ambient occlusion cache in memory. If caching is disabled but the feature is enabled, then ambient occlusion is performed on demand only when shaders call for its computation.
Cache Density: Upper bound to the number of ambient occlusion points per pixel.
Cache Points: Number of cache points close to the lookup location used for interpolation. Default is 64.

Options tab

Diagnostics

Diagnose samples

Diagnose Bsp

Diagnose grid

Renders a grid on top of all objects in the scene, in object, camera, or world space. Gives you an idea of the scene scale and rough estimates of distances and areas.

Grid size

Defines the size of the grid (in Diagnose grid).

Diagnose photon

Select one of the following options:

Density: When photon maps are used, select this option to replace all material shaders in the scene with an internal shader that produces a false-color rendering of the photon density.
Irradiance: When photon maps are used, select this option to replace all material shaders in the scene with an internal shader that produces a false-color rendering of the average of the red, green and blue irradiance components.

Photon density

Diagnose finalgather

Preview

Contains options for specifying what to include in a preview render in Render View.

Please refer to the mental ray User Manual, available from the Maya help, for more information about this setting.

Preview Animation

Render subsequent frames of the set animation range and preview all intermediate images inside Render View.

Preview Motion Blur

Calculate and preview render motion blur if enabled in the Render Settings. The Preview Animation option doesn’t need to be turned on for this to work.

Preview Render Tiles

Updates the Render Preview window in regular time intervals to show render progress. If this is turned off, only the final image is shown at the end of rendering.

Preview Convert Tiles

This option enables a plug-in conversion procedure for previewing image tiles when the primary framebuffer type is of a type that is not supported by Maya’s Render View (for example, floating point framebuffers, or color framebuffers with components larger than 8 bit).

The conversion procedure involves the clipping and rescaling (desaturation) of colors for display. This option is on by default.

Preview Tonemap Tiles and Tonemap Scale

The Preview Tonemap Tiles option previews image tiles for floating-point framebuffer types where the color values exceed the typical 0-1 range (because the color values are RGB). This option is on by default.

The Tonemap Scale value is used to rescale the color data of image tiles prior to clipping. This is useful when rendering high dynamic range images. The final rendered image is not affected by this value. The default value is 1.

mental ray Overrides

Displacement

Max Displace

Specifies the maximum displacement applied to object control points in a normal direction. This provides control over the otherwise automated displacement range to better focus tessellation where most needed. Set this value if you have any displaced objects in your scene.

A Max Displace value that is too large results in a correct image, but takes more time and uses more memory. If the Max Displace value is too small, parts of the displaced object may be clipped. The default value of 0 means the setting is not active.

A warning message appears if a displacement shader returns a value greater than the Max Displace value. This can result in rendered geometry appearing clipped.

Shadow Map

Shadow Map Bias

This option applies the specified Shadow Map Bias value to all light sources that do not have their own biases. This adds a slight offset to the shadow depths, resulting in a slightly shifted shadow. This option is useful in tuning shadows in specific cases, such as when rendering Fur.

The bias value should be smaller than the smallest distance between a shadow caster and a shadow receiver. However, bias values that are too small may cause self-shadowing.

Global Illumination/Caustics

Turn caustics and global illumination generators and receivers on or off for the entire scene.

Tessellation

Use these options to create and assign a Surface and, or Displace approximation globally to the scene.

Translation

Contains options for specifying the settings and items to be included when rendering a Maya scene with mental ray for Maya.

Export Exact Hierarchy

Tries to preserve the DAG hierarchy during processing. This produces additional mental ray instgroup entities. There are certain unresolved material inheritance issues in this mode, but it works well in the general case. Deeply nested DAG hierarchies may be translated much faster compared to the standard Maya iterator mode that always flattens the DAG. Default is off.

Export Full Dagpath

Uses the full DAG path names instead of the shortest possible name for mental ray scene entities. This is not required to generate a valid scene, but ensures reproducible names even if DAG entity names are reused in Maya. On the other hand, with deeply nested DAG hierarchy names, you may exceed the maximum supported name length in mental ray. Default is off.

Export Textures First

Collects all file texture references in the scene first. This ensures that missing texture files are reported early in the process, but may slow down scene processing depending on the number of file textures being used. It may also write out textures references that are never used in the shading graph, because it doesn't perform a complete scene graph traversal for performance reasons. Default is on.

Export Particles

Lets you export particles.

Export Particle Instances

Lets you export particle instances.

Export Fluids

Lets you export fluids.

Export Hair

Select one of the following options:

Hair Geometry Shader: The geometry shader creates the hair. This option should be used for rendering interactively in Maya and offers the best Maya Hair translation performance.
Off: Select this option if you do not want to export hair.
Hair Primitive: Select this option to convert Maya hair to native mental ray hair so that it can be rendered with mental ray standalone. This option can be used for rendering interactively in Maya or for exporting the file to render with standalone but better suited for mi file rendering.

Export Post Effects

Lets you export post effects.

Export Vertex Colors

Lets you force the export of all the CPV (color per vertex) data for all the meshes in your scene. Exporting CPV data can be process-intensive, so do not turn on this attribute unless necessary.

Performance

(Performance options are within the Translation section.)

Prune Objects Without Material

This option ignores objects without materials during translation so that they are not part of the final rendered scene. This option is on by default.

Optimize Non-animated Display Visibility

This option ignores non-animated invisible scene entities during translation so that they are not part of the final rendered scene. This option is on by default.

Note:

You should turn Optimize Non-animated Display Visibility off if an object’s visibility is animated.

Optimize Animation Detection

When this option is turned on, the processing of non-animated geometry is significantly optimized because mental ray for Maya detects animated nodes prior to processing the scene. This is especially useful for scenes that contain many static objects and only a few simply animated objects. This option is on by default.

Note:

Optimize Animation Detection is limited in several ways, as it currently can only detect key frame animations, but not a) pre and post infinity curve cycles and b) animations generated by expressions and pre/post RenderMel scripts.

Optimize Vertex Sharing

This is to produce a more compact vertex representation (vertex lists) for meshes that exhibit a lot of vertex sharing. Only first-level sharing is exploited in mental ray for Maya.

Optimize Raytrace Shadows

This option optimizes the algorithm used to assign mental ray shadow shaders to materials. When turned on, mental ray determines whether shadow shaders are necessary before assigning the shader. This option is on by default.

Export Render Proxy

Select this option to render the proxies in your scene instead of the placeholder geometry that you used. For more information regarding render proxies, see Using render proxies in your scene.

Export Motion Segments

This option enables detection and translation of motion vector segments of shape nodes, a method to render non-linear motion paths from shape animations with mental ray.

If this option is enabled, then the Motion Steps option triggers this number of extra evaluations of the scene at equi-distant times within the Maya shutter interval (render camera shutter * motion blur by). Any shape deformation appearing in these time steps is expressed as a motion segment vector in mental ray. The resulting motion trail when rendering with motion blur matches the actual shape animation more closely, since it approximates any non-linear movement with a set of linear segments (up to 15).

Note:

Raising the Motion Steps value beyond 1 (the default) implies a performance degradation of translation caused by extra subframe scene evaluations in Maya and computations in the plug-in.

Export Triangulated Polygons

This option processes all polygon meshes as tessellated triangles, based on Maya’s tessellation. This allows more efficient use of memory so that large scenes with large polygon meshes render with less memory usage.

This option is on by default.

Note:

The Export triangulated polygons option automatically switches back to exporting mesh geometry if it encounters subdivision meshes in the scene.
In some rare cases, Export triangulated polygons may cause a decrease in render quality. Turn this option off if this occurs.

Export Shape Deformation

Compare actual geometry to determine any kind of shape deformation during animation and motion blur, required to produce exact motion blur information and support incremental changes in mental ray. If none of these conditions are true, turning this off may speed-up scene processing. Default is on.

Force Motion Vector Computation

This option forces the computation of motion transform and per vertex motion vector. Normally, this is automatically done when you enable motion blur; however, if you do not want mental ray to render the motion blur effect, but you want the motion vectors and motion transforms to be available during rendering (without blurring the image), you can enable this option so that mental ray for Maya provides the motion data. For example, you must enable this option if you creating the motion vector type passes (2D Motion Vector, 3D Motion Vector, Normalized 2D Motion Vector).

Force raytraced camera clipping

When enabled, the near and far clipping planes are respected for primary rays shot from the camera when rendering with mental ray for Maya.

However, this attribute should be used with caution in combination with lens shaders bending eye ray directions (for example, fisheye-style shaders), as it may lead to unexpected results: clipping is done based on the camera only.

Force raytraced camera motion vector computation

If you disable Scanline and enable BSP2, you can enable this option to enforce the adding of a camera motion effect to the computed motion vectors.

Export Polygon Derivatives

Calculate and export first order derivatives for polygons. This is required for bump mapping and shader filtering to produce comparable results to Maya.

When on (default), the Maya derivatives and Smooth Polygon Derivatives options are available.

Maya Derivatives

This option uses Maya’s derivatives calculation for bump mapping and shader filtering, providing compatibility with Maya.

This option is off by default, and is only available when Export Polygon Derivatives is on.

Smooth Polygon Derivatives

This option calculates derivatives by taking into account vertex sharing to decide if texture seams can be ignored. This calculation avoids artifacts due to UV seams.

This option is off by default, and is only available when Export Polygon Derivatives is on.

Export Nurbs Derivatives

Enable calculation of first order derivatives for NURBS objects in mental ray. This is required for bump mapping and shader filtering to produce comparable results to Maya. Default is on.

Export Objects On Demand/Threshold

Use the Export Objects On Demand option to control the processing of objects in your scene. This option is particularly effective in scenes that have objects beyond the view of the camera. In this case, mental ray does not process the objects beyond the camera view, therefore reducing processing time.

When Export Objects On Demand is on, it includes a Threshold value that lets you tune on demand translation for objects. Objects with a number of vertices or controlled vertices greater than the threshold value are not translated until a ray hits the bounding box. A value of 0 results in all objects processed on demand. In this case, translation is quick, but render time may not improve. You can select larger objects for on demand translation by raising the Threshold value. For polygons, the Threshold value relates to the number of vertices. For NURBS, the Threshold value relates to the number of control points. For Hair, the Threshold value relates to the number of hair.

This option is off by default.

Allocate On Heap

Select this option so that the shading engine stores temporary data on the heap (dynamically allocated memory). When raytracing through transparent materials, the shading engine stores temporary data on the rendering thread's memory stack. Occasionally, a rendering thread may run out of space on the stack, causing Maya to stop unexpectedly due to a stack overflow. To workaround this, select this option so that the shading engine stores temporary data on the heap instead of on the memory stack. Selecting this option causes mental ray for Maya to render slower, but it may prevent Maya from stopping unexpectedly due to a stack overflow when using a large number of render passes in a scene with many layers of transparent objects.

Customization

(Customization options are within the Translation section.)

Please refer to the mental ray User Manual, available from the Maya help, for more information about this setting.

Render Shaders With Filtering

This option causes mental ray shaders to perform filtering in individual shaders. This option reduces texture and bump mapping artifacts, and is on by default.

Render Shaders With Filtering requires that the Export Polygon Derivatives option be turned on (Render Settings window, Options tab, Translation > Performance section).

Use Legacy Maya Base Shaders

Disable this option to use render pass compliant shaders. This option is off by default. Enable this option to use legacy Maya base shaders.

Export State Shader

This should only be turned off when exporting to .mi file and only the standard mental ray base shaders are used exclusively (for example, when no Maya shaders are used). Default is on.

This option should be enabled when you use the multi-render pass feature.

Export Light Linker

This controls the export of the Maya Light Linker node. Default is on.

Export Maya Options

This enables the export of special options as mental ray user data, to control several advanced Maya features performed in the mayabase shaders. Default is on.

Export Custom Colors

Common mental ray shaders often use 4-component RGBA color parameters instead of the usual 3-component Maya color compounds. With this option enabled all custom nodes are provided with full RGBA colors, with the alpha component set to 1.0 (fully opaque). Default is on.

If this option is disabled, then mental ray shaders should ensure that they can set the alpha component explicitly to reasonable values, away from mental ray’s default, which is 0 (fully transparent).

Export Custom Text

This should only be turned on for .mi file export to recognize and translate Custom Text nodes. It is automatically turned off for the integrated rendering if Preview Custom has been turned off.

Export Custom Data

If enabled, special custom attributes on polygon meshes are recognized and exported as vertex user vectors to mental ray.

Export Custom Vectors

This option enables recognition of an optional miCustomMotion boolean dynamic attribute on geometry shape nodes. If such an attribute has been found then motion vectors are always generated and exported, even if they are of zero length. This is required for certain mental ray shaders that are allowed to perform motion blur calculation in the shader, for example for displacement motion blur.

Custom Entities

Contains controls for creating and managing custom global text, textures, and scene element text. Use these options to take advantage of alternate channel computations when writing custom shaders.

Pass Custom Alpha Channel: This option passes the mental ray alpha component of the final color as the alpha channel, ignoring the Maya alpha component. This is useful when a custom shader is producing an alpha value. This option is on by default.
Pass Custom Depth Channel: This option overrides the Maya depth channel calculation with the default mental ray depth channel calculation. This option is useful when you want to revert to using the mental ray depth calculation, instead of the default Maya calculation. This option is off by default.
Pass Custom Label Channel: This option passes label data untouched, rather than allowing adjustment for Maya shaders. This option is off by default.

Custom Globals

These allow for the customized output of version, link, and include statements. If these text boxes are empty, mental ray for Maya generates the usual default statements that are required for rendering Maya scenes. Otherwise, it expects a space separated list of entries, which are exported in the appropriate section of the mi stream instead of the defaults.

In the Versions text box, the first entry is written as the min version, the second entry as the max version statement.

The Includes text

base.mi mayabase.mi

in the text box results in:

$include "base.mi"
$include "mayabase.mi"

in the final output.

The same happens for the Links text.

Custom Scene Text

Global Text

The global text control is especially useful for adding custom link, $include and code statements. It can also be used to add texture and shader declarations.

Within a scene many types of text nodes can be created, but just the selected one gets exported. The contained text is written once at the beginning of the .mi stream right before the first option block gets written. Certain modes are available which determine how the custom text should be applied to the generated output.

Note that incorrect .mi text could be introduced that cannot be recognized nor corrected by mental ray for Maya processing.

Options Text

Similar to Global Text, Options Text is provided to allow customized mental ray option settings. It offers the ability to extend or replace the generated option settings. For example, custom framebuffer statements should be added here.

Lights, Cameras, and Scene Text

These enable custom text on certain sequentially exported sections like lights section, camera section, and scene section, in this order. Those sections can be extended or completely replaced, similar to the Global Text. For example, custom lights can be appended to the generated output. This would require that the scene section be extended with the incremental change of the new root instance group including the new light.

Root Group Text

The Root Group Text control can be used to customize the final root group specifying all cameras and objects to be rendered. This control is applied to the content of the root group, not the whole root group section (like other types of scene text).

Render Text

The Render Text control can be used to customize render commands for renderable cameras. For example, it can be used to perform operations between renderings, like file operations.