This page gives information about the Velocity Render Element.
||Render Setup window|| > Render Elements tab > Add button > VRayVelocity
This render element is enabled through the Render Elements tab of the Render Setup window in 3ds Max and displays its parameters in a rollout at the bottom of the window:
vrayVFB – When enabled, the render element appears in the V-Ray Virtual Frame Buffer.
deep output – Specifies whether to include this render element in deep images.
clamp velocity – Sets the limit for max velocity. When enabled, this option limits the max velocity value to 1 for floating point images, 255 for 8-bit images, or 65535 for 16-bit images. This option is useful only when writing to an 8-bit or 16-bit file format.
max velocity – Used to scale the velocity values written to the render element so that they fit within the range specified by the clamp velocity parameter. This is only useful if writing to an 8-bit or 16-bit file format.
max velocity in last frame – Shows the maximum velocity value that was found while rendering the last image. This is a read-only parameter and can be used as a guide for setting the max velocity parameter.
ignore z direction – Disregards motion along the Z axis.
Exclude – Opens a dialog where objects can be excluded from the render element.
A common workflow for using this render element is to first locate the frame in the sequence that has the most motion, render the frame in 3s Max with the Velocity Render Element enabled, and then note the max velocity in last frame value, which is displayed in the parameters for this render element. Finally, enter this value (or a slightly larger value) for the max velocity parameter when rendering the entire sequence. This workflow provides the maximum range of colors in the Velocity Render Element for the most flexibility during compositing.
The Velocity Render Element is useful for adding motion blur in post production at a composite level without the need for rerendering. In the composite shown below, motion blur was added based on the amount by which the color differs from medium gray. The feathers that were given a pale yellow color in the render element are the most blurred.