A joint subcommittee comprising members of the American Society of Cinematographers, the Art Directors Guild and the Visual Effects Society has agreed upon the following definitions:
Previsualization, or previs, is a collaborative process that generates preliminary versions of shots or sequences predominantly using 3D animation tools and a virtual environment. It enables filmmakers to visually explore creative ideas, plan technical solutions, and communicate a shared vision for efficient production.
There are a number of types of previs in current practice, including:
Pitchvis illustrates the potential of a project before it has been fully funded or greenlit. As part of development, these sequences are conceptual, to be refined or replaced during preproduction.
Technical Previs incorporates and generates accurate camera, lighting, design and scene-layout information to help define production requirements. This often takes the form of dimensional diagrams that illustrate how particular shots can be accomplished using real-world terms and measurements.
On-Set Previs creates real-time (or near-real-time) visualizations on location to help the director, cinematographer, visual-effects supervisor and crew quickly evaluate captured imagery. This includes the use of techniques that can synchronize and composite live photography with 2D or 3D virtual elements for immediate visual feedback.
Postvis combines digital elements and production photography to validate footage selection, provide placeholder shots for editorial, and refine effects design. Edits incorporating postvis sequences are often shown to test audiences for feedback, and to producers and visual-effects vendors for planning and budgeting.