mental ray attributes

mental ray Settings

Setup GeoShaders

Sets up a mental ray geometry shader used to generate the XGen render time geometry. By default, the setup is set to Automatically, which means it is done when a new Description is created (see mental ray Help topic "mental ray XGen hair physical"). To manually setup a shader for the current Description, select Manually and click Setup.

Render Mode

Live

XGen queries patches and guide animation directly from Maya. This mode does not support Motion Blur and reuses information the preview generated.

Batch Render

Reads geometry and animation from files. This mode is always on when using Batch Render. You must first export the patches and guide animation to caches. Use this mode to make sure your caches are properly exported using Batch Render.

See Export Patches for Batch Render Options.

mental ray Approximation Settings

Degree

Spline primitives can be rendered as linear segments or as cubic Bezier curves. Set to Cubic for Card primitives. This setting has no effect on Archive and Sphere primitives.

Linear

Renders Spline primitives as linear segments.

Cubic

Renders Spline primitives as smooth Bezier curves. You can use view dependent approximation.

Subdivisions

(for Linear Degree only) Defines the number of segments to use between control points.

Type

(for Cubic Degree only) Sets the type of mental ray approximation to use when subdividing render time hair Bezier curves or card NURBS patches.

No Approximation

Render time geometry is not subdivided.

Parametric Approximation

Subdivides render time geometry a number of times between control points.

Fine Approximation

Subdivides render time geometry until edges hit a given length in pixel size. This option is view dependent.

Sub Pixel Size

Subdivides geometry until edges hit a maximal length in pixel size. This option is view and resolution dependent. Values below 1.0 split the geometry within the same pixel. This is useful to render very thin hair with tube normals and a high number of samples. Values above 1.0 produce geometry that does not look smooth. Use this attribute to optimize render time if the geometry is far away from the camera.