The compositing process takes the rendered images from the previous phase and combines layers of ready-made material (usually input files) to create enhanced visual elements – encompassing everything from the atmosphere, mood lighting, to colour overlays and textures. 3D compositing can differ from 2D compositing, depending on the way in which layers can be made to interact and realistically effect with each other (wiseGEEK, 2016). Within 3D compositing, separate layers of input files allows the elements to overlap, thus creating a more realistic effect.
The materials can be sourced from various disciplines, and can include rendered computer animation, special effects, graphics, 2D animation, live action and static background plates (Creative Skill Set, 2017).
Programs like After Effects offer processes such as colour correction, blurs, RSMB Motion blurs and Lens flares (Campbell, 2010).
Enhancing the finished product if lacking in depth or weight can be achieved by rendering ambient occlusion passes, or ‘contact shadows,’ darkening the areas where two objects interact. This can help create the illusion of a unified space and add weight to the scene (Slick, 2017). It is also common for artists to tweak complex elements (smoke, fire, hair, etc.) in Photoshop post-production. Specified brushes can add subtle layers of detail that would otherwise be time-consuming to render within a constrained 3D program.
Colour-grading is an important step in the final composition, as colour, as a visual element, helps to influence mood and tone of the final product. Adjustments to the brightness, contrast, hue, saturation and colour balance can aid to create the desired aesthetic.
An example of lens distortion. Retrieved from https://answers.unrealengine.com/questions/160433/how-to-make-lens-distortion-work.html
Lens distortion can be applied to scenes for a variety of reasons, to create low contrast, flares, and other intended blemishes depending on the desired outcome of the film. Chromatic aberration and vignetting are two forms of lens distortion that mimic real-life imperfections on camera lenses, and be added subtly to “work wonders” on an image (Slick, 2016). Other techniques include noise and film grain, which work to create a cinematic finish.
Campbell, N. (2010) The Importance of Compositing: A Layer by Layer Breakdown in After Effects. Retrieved from https://greyscalegorilla.com/tutorials/the-importance-of-compositing-a-layer-by-layer-breakdown-in-after-effects/
Creative Skill Set (2017) Compositor. Retrieved from http://creativeskillset.org/job_roles/358_compositor
Slick, J. (2016) Finishing a 3D Render: Colour Grading, Bloom, and Effects. Retrieved from https://www.lifewire.com/color-grading-bloom-and-lens-effects-2126
Slick, J. (2017) Finishing a 3D Render – Passes, Compositing, and Touch Ups. Retrieved from https://www.lifewire.com/passes-compositing-and-touch-ups-2127
wiseGEEK, (2016) What is 3D Compositing? Retrieved from http://www.wisegeek.com/what-is-3d-compositing.htm