Compositing modes

Internal compositing

Internal compositing is the default. This can be changed in World Settings inside the Editor.

Internal compositing can be thought of as an upstream image mixing, where the video and the graphics are combined inside the graphics engine. The output from the graphics system is a fill signal
Internal Compositing is used where you want access to advanced interactions between video and graphics, such as virtual reflections and shadows, virtual objects both in front of and behind on-camera talent, and virtual camera moves, as well as subtle lighting effects such as bloom and light wrap.
Pixotope supports both external and internal chroma key inputs for Internal Compositing
Pixotope supports compositing in linear and video compositing color spaces

External compositing is considered a legacy feature and should only be used when Internal is not practical
External compositing can be thought of as downstream image mixing, where the graphic system only outputs the graphics fill and the relevant key. The graphics and video are combined in an external image mixer or keyer
External compositing can be used when you do not need advanced compositing functionality such as virtual camera or internal chroma keyer, or for other reasons prefer a downstream image mix
Useful for larger-scale virtual sets where talent reflection and shadow is not needed