What is a previs (previsualisation)?
A previs is simply a way of visualising complex scenes in a 3D animation before moving on to the more detailed and time consuming parts of the process and without committing to the long render times associated with 3D. It’s the 3D equivalent of a storyboard.
It allows an animation company to experiment with different staging and art direction options, such as lighting, camera position and motion without having to incur the time costs of actual production.
A previs is often initially presented as a greyscale render like the one shown below. This type of previs is fast to export and, since no colours or materials are applied, helps separate the story from the style.
Once the initial previs has been approved, the animation is refined and simple lighting and materials are applied. A low quality, grainy render is exported for review.
This low quality, grainy render can still taken a significant time to export but is substantially faster than the time taken for the final render. This version is used to judge details such as lighting, colours, reflections and transparency.