The first step of 3D animation post-production in 3D animation studios is called compositing. It involves taking the render passes from the production stage and combining them together or mixing in additional images or adjustments layers, to create a more cohesive composition.

The rendering of a 3D scene is often performed in separate layers or render passes. Render passes give more control over different aspects of a scene. This way, you will be able to fine-tune your lighting, coloring or other adjustments, create rendered variations and choose the best one without having to render the entire scene again and again.

In 3D animation, compositing is about combining two or more render passes or adding layers to create a single image or series of images with predefined properties. Several compositing programs can be used to touch-up and edit digital renders or add special effects by compositors in an animation studio.