MayaMan Help Contents

# MayaMan Motion Blur

The motion blur panel in the MayaMan Globals dialog controls renderman motion blur parameters.

#### Linear Blur

When this mode is enabled the geometry and transformation information is only sampled on even frame boundaries. This may result in faster rib gen and less disk space used. When enabled the GUI changes to a simplified form of the regular motion blur controls.

#### Clamp Motion

When enabled (the default) prman 12.5.1's default motion blur interpolation algorithm is selected. When disabled, a more sophisticated interpolation strategy is selected, there is no time/memory penalty and the results are considered superior, it's just not selected by default to avoid look changes.

#### Time In Zero To One Range

When enabled the shutter/motion times used in the rib will all be based in the 0 to 1 range which makes the built in time variable useless in shaders. When disabled (the default) the time range will be based on the frame number being rendered.

#### Enable Blur

You can enable or disable Motion, Vertex and Camera blur using the three checkboxes in this dialog. Motion blur can occur when objects move past the camera. Vertex blur can occur when an object is quickly deforming. Vertex blur also controls the blurring of particles. Camera blur occurs when the camera is moving quickly, and blurs all objects in the scene.

#### Motion Blur Amount

These parameters control the amount of blur applied to objects. 100% will show an object blurring between its position in neighbouring frames, while 200% will blur twice as much, looking at the difference in object positions between the current frame and two frames away.

#### Number of Segments

Normally objects are blurred linearly between their start and end positions. However, using this parameter, objects can be sampled in multiple positions and blurred between them. This is useful for objects moving in an arc, such as a helicopter rotor blade, so that it blurs in a smooth curve rather than in linear segments.

#### Direction

Motion blur can blur objects between their position at the current and previous frame ('Backward') the current and next frame ('Forward') or half-way in either direction ('Centered'). For forward and backward motion blur modes the shadow will always be produced at the frame's time so authors of procedurals should now emit their time samples for backward motion blur in reverse order so that shadow application occurs properly.

#### Motion Blur Shadows and Reflections

This option will put the "motionrays" attribute into the RIB file just after WorldBegin. When both motion blur (above) and this option are enabled, then reflections and shadows of motion blurred objects will too render with motion blur.
To improve the quality of motion blurred shadows and reflections you will have to increase the no of samples used: The no of samples used for reflections can be found in the MayaMan Material Attributes (Reflection Samples). The no of samples used for shadows can be found in the Maya Light Shape Attributes (Shadow Rays).
Note that this attribute (motionrays) can be overridden at several levels, namely in the Global Options (here), in the MayaMan Material Attributes, and in the MayaMan Model Attributes.

#### PRMan 13 Shutter Opening

PRMan 13 allows shaping of the shutter openness. When disabled the default of of 'FullyOpen=0' and 'BeginClose=1' is used which results in the shutter being instantly fully open and remaining fully open until the end of the time range then instantly snaps shut.

When enabled, the shutter will start opening at the beginning of the time range and be fully open by the time it hits the 'FullyOpen' fraction of the time range, it then remains fully open until the 'BeginClose' fraction of the time range is encountered, then the shutter starts to close and is fully closed at the end of the time range.

The MayaMan defaults, when enabled, is configured so that the shutter is opening half the time and closing half the time. This produces a motion blur fairly similar to a real motion picture camera.

#### Air 5.0 Adaptive Motion Blur

Air 5.0.4 and later can modify the effective pixel samples setting dynamically so that motion blur can be smoothed out without penalizing parts of the image that don't contain blurred objects.

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