In visual effects, a background plate is an image or motion picture footage that is used as the basis for a composition. The background plate forms the backdrop against which other elements, such as CG characters or objects, are added.
The background plate is filmed specifically for the visual effects shot in question in many cases. However, it is also common for background plates to be sourced from stock footage libraries or to be repurposed from other projects. Regardless of its origins, the background plate plays a crucial role in creating believable visual effects.
Without a detailed and convincing backdrop, even the most well-executed VFX can fall flat. As such, considerable care and attention must be given to selecting and creating background plates that will serve as the foundation for successful visual effects shots.