Render Settings: mental ray tab

New in Maya 8

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

Quality Presets

When you select a Preset here, settings in the applicable sections in the mental ray tab are automatically set (for example, PreviewGlobalIllum turns on Global Illumination and sets other defaults in the Caustics and Global Illumination section).

Use these settings as a starting point for rendering your image at a given quality and with a certain effect.

Custom

Lets you specify the mental ray for Maya quality settings independently.

Draft

Gives you a relatively good indication as to what scene will look like while taking the least amount of processing time.

DraftMotionBlur

Gives you a relatively good indication as to what scene will look like, with motion blur, while taking the least amount of processing time.

DraftRapid
Motion

Gives you a relatively good indication as to what the scene will look like, when using Rapid Scanline, while taking the least amount of processing time.

Preview

Slightly better than Draft, takes a little more processing time, but achieves a good balance between quality and time.

PreviewCaustics

Slightly better than draft (but includes caustics), takes a little more processing time, but achieves a good balance between quality and time.

Preview
FinalGather

Slightly better than draft (but includes final gather), takes a little more processing time, but achieves a good balance between quality and time.

Preview
GlobalIllum

Slightly better than draft (but includes global illumination), takes a little more processing time, but achieves a good balance between quality and time.

Preview
MotionBlur

Slightly better than draft (but includes motion blur), takes a little more processing time, but achieves a good balance between quality and time.

Preview
RapidMotion

Slightly better than Draft (when using Rapid Scanline), takes a little more processing time, but achieves a good balance between quality and time.

Production

Use this when testing the final rendering or rendering the final image(s) that do not contain motion blur.

Production MotionBlur

Use this when testing the final rendering or rendering the final image(s) that contain motion blur.

Production RapidFur

Production quality results using Rapid Scanline for scenes with fur.

Production RapidHair

Production quality results using Rapid Scanline for scenes with hair.

Production
RapidMotion

Use this when testing the final rendering, or rendering the final image(s) when using Rapid Scanline.

Production
FineTrace

Production quality results for scenes with raytracing. This preset turns on Scanline raytracing, and provides quick results.

Rendering Features

New in Maya 8

Primary Renderer

Scanline

Scanline rendering is used as a faster way (in most cases) of rendering. By default, mental ray for Maya uses this option when possible. However, if you need to include reflections and refractions in your scene, you should enable Raytracing as a secondary effect. See Secondary Effects for more information.

Rasterizer (Rapid Motion)

A substantially faster motion blur algorithm alternative. Formerly named Rapid Scanline.

Raytracing

Turn off the scanline renderer and force mental ray to always use raytracing instead.

Notes
  • For small or static scenes, scenes with final gather, or scenes without much depth complexity, scanline rendering is a faster way of rendering. However, for large scenes, scenes with a lot of hair, or scenes with a lot of motion blur, you should use rasterizer rendering instead.
  • Contour rendering does not currently work with the rasterizer.
  • Default quality settings for the Rasterizer are typically higher than those of the default scanline. For example, the default value of 0 for Visibility Samples is equivalent to a Min/Max Sample Level of 1 for scanline.

Secondary Effects

Raytracing

Turns raytracing on or off. Enables reflections and refractions.

Final Gathering

Turns final gather on or off.

Caustics

Turns caustics on or off.

Global Illumination

Turns global illumination on or off.

Shadows

Turns shadows on or off.

Motion Blur

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), then does a linear interpolation based on the objects to simulate. It is fast but limited.

Full

Full is slower to render, but gives true (that is, exact) motion blur results.

Anti-Aliasing Quality

Controls how mental ray for Maya anti-aliases objects during rendering.

For more information about anti-aliasing and image quality, see Anti-aliasing and flicker.

Raytrace/Scanline Quality

New in Maya 8

Sampling Mode

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.

Min Sample Level

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

Max Sample Level

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

Number of Samples

New in Maya 8

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. Custom Sampling does not impose this restriction.

Contrast Threshold

Use the slider to set your contrast threshold. Lowering these values 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).

Rasterizer Quality

Visibility Samples

This value indicates the number of samples used for anti-aliasing. The default value is 0, and the maximum value is 8. A value of 0 defaults to the mental ray core value (4).

Shading Quality

This value indicates the number of shading samples per image pixel. The default value is 1, and the maximum value is 4.

Multi-pixel Filtering

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.

Box

The fastest way to get relatively good results.

Triangle (default)

More processor intensive than box, but offers even better results.

Gaussian

Produces the best results, but is the slowest to render.

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.

Filter Size

Updated in Maya 8

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.

Sample Options

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.

Raytracing

Ray Tracing

If on, mental ray for Maya raytraces the scene during rendering. 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.

See also Max Trace Depth.

Refractions

The maximum number of times a ray can be refracted through non-opaque surfaces.

See also Max Trace Depth.

Tip
If refractions turn black, make sure Refraction is set to a high enough value.

Max Trace Depth

While the Reflections setting and Refractions setting each set the maximum number of times a ray can reflect or refract (respectively), this setting sets total number of penetrations that can occur regardless of whether the penetration is a result of reflection or refraction. For example, if reflections = 5, refractions = 5, but max depth trace = 4, then any combination of reflection and refraction bounces can take place, up to a maximum of 4.

Shadows

Updated in Maya 8

The maximum number of times a shadow ray will penetrate a transparent or refracting object.

Consider, as an example, a glass sphere and a metal sphere. The shadow of the glass sphere is not as dark as the shadow of the metal sphere because some light passes through the glass sphere.

In mental ray, this model is represented by a shadow ray penetrating the glass sphere. The shadow ray only stops when one of the following is reached: 1) all light is blocked, 2) the number of times that the ray has penetrated the sphere is equal to the value of this attribute.

Reflection/Refraction Blur Limit

New in Maya 8

Determines the blurriness of secondary reflections or refractions. The higher the Reflection/Refraction Blur Limit, the more the secondary reflections/refractions are blurred.

Acceleration

Acceleration Method

Updated in Maya 8

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.

See also Use average BSP (mental ray for Maya) settings.

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.

Hierarchical Grid

The Grid acceleration method subdivides on a regular grid in space. Its memory usage is more predictable, but it may be slower if the geometry is not evenly distributed in the scene.

BSP

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.

Grid

Auto Resolution

New in Maya 8

Instead of specifying a resolution of the hierarchical grid, you can allow mental ray for Maya to calculate the optimal resolution. If this option is selected, and mental ray has performed the necessarily calculations, the computed resolution is displayed in the Resolution attribute below.

Resolution

If the hierarchical grid algorithm is used, this option sets the number of grid voxels.

mental ray for Maya can use subgrids to subdivide voxels with many triangles, so that scenes with dense concentrations in specific areas do not need force the increase of the global number of voxels just to capture the regions of high density. A grid resolution of 2 lets the grid algorithm degenerate to an octree algorithm.

Max Size

If the hierarchical grid algorithm3.1 is used, this option sets the maximum number of triangles in a grid voxel. If there are more, and the grid depth permits it, the voxel is subdivided into a subgrid. Note that size int must really be an integer; a floating-point value causes the statement to be ignored and a warning to be printed.

Max Depth

If the hierarchical grid algorithm3.1 is used, this option sets the number of recursion levels. If a voxel of a grid contains too much detail, it is subdivided by a subgrid for that voxel, which adds another level. The default is 2 for two levels (subdivided voxels cannot be subdivided again).

Shadows

Shadows

Turns shadows on or off.

Shadow Method

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.

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 the mental ray Shaders Guide in the Maya Help.

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.

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

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

Turns shadow maps on or off.

Shadow map parameters are specified for each light source. The default is off because shadow maps, while often significantly faster, always assume opaque objects.

Format

Detail

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

Unlike the standard 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

Updated in Maya 8

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.

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.

OpenGL Acceleration

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.

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.

Motion Blur

See also mental ray for Maya motion blur.

Motion Blur

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), then does a linear interpolation based on the objects to simulate. It is fast but limited.

Full

Full is slower to render, but gives true (that is, exact) motion blur results.

Calculation

See also mental ray for Maya motion blur.

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.

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.

Custom

Custom Motion Offsets

Turn on this option if you want to set values for Motion Back Offset and Static Back Offset. Use these custom motion offsets to define the time steps where motion blur information is captured. This option is off by default.

Motion Back Offset

This value determines the start point of the time interval used for motion blurring. It is an offset to the current time in frames. The default value is 0.5, and corresponds to Maya.

Static Object Offset

This value determines the time used to render static objects. The default value is 0, and corresponds to Maya.

Rendering

Shutter Open, Shutter Close

Updated in Maya 8

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).

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.

Time Samples

New in Maya 8

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.

Time Contrast

Color Contrast

Updated in Maya 8

These settings determine a threshold for adaptive time sampling. Lower values cause more time samples, which result in more accurate motion blur but increased render times.

Note
This attribute is not for use with the rasterizer. In general, use of the Time Samples attribute should be enough to control the quality of motion blur.

Caustics and Global Illumination

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 Caustic Scale value. Caustic Scale is off by default.

Caustics Options

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 (Caustic Accuracy) emitted by the light source.

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.

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 Global Illum Scale value. Global Illum Scale is off by default.

Global Illumination Options

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.

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.

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.

Direct Illumination Shadow Effects

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

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.

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.

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 in the Lighting guide.

Accuracy

Updated in Maya 8

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 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

New in Maya 8

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

Point Interpolation

New in Maya 8

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.

Scale

Updated in Maya 8

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.

Rebuild

If this is on (default), any previously generated Final Gather file is ignored and all final gather points are recomputed. See 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.

Freeze

The Freeze option stops any new data from being written to the final gather file. This option causes mental ray for Maya to compute the final gather solution just once for a full sequence of animation. It is useful to reduce light flickering in your animation.

Tips
  • 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.

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:

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.

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.

Final Gathering Options

Optimize for Animations

New in Maya 8

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.

Use Radius Quality Control

New in Maya 8

Switch back to the old 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.

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.

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.

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.

Secondary Diffuse Bounces

Turn on the Secondary Diffuse Bounces option to allow 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. Turn this option on 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. This option is off by default due to extra performance cost.

Secondary Bounce Scale

New in Maya 8

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

Diagnostics

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.

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

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

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.

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.

Render Options

Features

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

Defaults

Object Flags

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.

Shader Options

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.

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.

Tessellation

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

Caustics/Global Illumination

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

Framebuffer

Primary 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.

Gamma

Use this setting to apply gamma correction to rendered color pixels to compensate for output devices with a nonlinear color response.

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.

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.

RGB (default)

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) 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, 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. 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.

User Framebuffer

Updated in Maya 8

Click the Open Editor button to open the miDefaultOptions Attribute Editor. Only use the Frame Buffers section of the Attribute Editor. For all other settings, use the Render Settings window.

Contours

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

General

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 colour used to flood or fill the entire frame as the background colour before rendering the contour. In other words, this is the color onto which the contours caused by Hide Source are drawn.

Contours

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 Contours

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 tesselation

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.

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.

Translation

Updated in Maya 8

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

Note
In Maya 8.0, the Export Verbosity attribute was used to control the rendering verbosity. In Maya 8.5, this control has been moved to the mental ray Render Option editor and the mental ray Batch Render Option editor. See Render > Render Current Frame and Render > Batch Render for more information.

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 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 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.

Notes
  • 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.

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.

This option is off by default.

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, mental ray tab, Translation > Performance section).

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.

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 off.

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.

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.

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 off 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.

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 in the Lighting guide.

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

Physical Sun and Sky

New in Maya 8

When you click the Create button, a network containing the mia_physicalsky, mia physicalsun, mia_exposure_simple 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 of the Lighting guide.

 

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