Trace/Bounce Limits group

• Physically Correct (Unlimited)(The default.) When chosen, light bounces are unlimited, and are calculated as long as the renderer continues to run.
• Maximum Number of Light BouncesWhen chosen, limits the number of light bounces to the value you set. Default=4.

  Limiting the number of light bounces can speed up a rendering. This option can be helpful when you want to render a preview that doesn’t have to have full and finished reflections.

  If you limit the number of light bounces, scenes can appear darker than the final rendering with unlimited bounces would appear. This is true especially for interior scenes, and exterior scenes that are lit from all around (typically by the sky).

Image Filtering (Antialiasing) group

Determines how multiple samples are combined into a single pixel value.

Type

• BoxSums all samples in the filter area with equal weight. This is the quickest sampling method.
• Gauss(The default.) Weights the samples using a Gauss (bell) curve centered on the pixel.
• TriangleWeights the samples using a pyramid centered on the pixel.

Width

Specifies the width and height of the sample area. Increasing the value of Width can soften the image, but it increases render time. Default=3.0.

Displacement (Global Settings) group

View

Defines the space for displacement. When View is on, the Edge Length specifies the length in pixels. When off, the Edge Length is specified in world space units. Default=on.

Smoothing

Turn off to have the iray renderer correctly render height maps. Height maps can be generated by Normal Bump mapping.

When using only height maps in the scene, make sure this option is off. If some objects in the scene use height maps while others use standard displacement, apply smoothing on a per-object basis.

When on, the iray renderer simply smoothes the geometry using the interpolated normals, making the geometry look better. This result, however, cannot be used for height map displacement because smoothing affects geometry in a way that is incompatible with height mapping.

Edge Length

Defines the smallest potential edge length due to subdivision. The iray renderer stops subdividing an edge once it reaches this size. Default=2.0 pixels.

Max. Displace

Controls the maximum offset, in world units, that can be given to a vertex when displacing it. This value can affect the bounding box of an object. Default=0.508m (meters).

TipIf displaced geometry appears to be “clipped,” try increasing the value of Maximum Displace.

Max. Subdiv.

Controls the extent to which the iray renderer can recursively subdivide each original mesh triangle for displacement. Each subdivision recursion potentially divides a single face into four smaller faces. Choose the value from the drop-down list. Range=4 to 64K (65,536). Default=16K (16,384).

For example, using the default value means that the iray renderer can subdivide each displaced mesh triangle into as many as 16,384 smaller triangles.

Material Override group

Material Override allows you to render a scene with all its materials replaced by a single master material. For example, if you want to do a shadow study using volume only, with a single uniform color, use these controls to specify a neutral gray material. When you render, all surfaces will use the gray material.

Enable

When on, rendering uses the override material for all surfaces. When off, surfaces are rendered with the material applied to them in the scene. Default=off.

Material

Click to display the Material/Map Browser and choose a material to use as the override. Once you have chosen an override material, this button displays the material name.