Visual production allows the filmmaker to see what a shot look like in its final form. Visual production is a process where real-world filmmaking and digital effects occur simultaneously. This is in contrast to green/blue screen where the onset cast had the visualize in their minds what the shot will look like.
Virtual production finds it base in video projection being used as backgrounds in film shoots. With video production where the movie relies heavily on green screen it makes it harder to visual the actual shot. Lighting, camera angels and more are hard to predict. Avatar was one of the first movies using virtual production.
How does it work
Today’s popular usage of virtual production is using a set of LED walls. Combined with unreal engines. Resulting a photorealistic background. Before filming the camera need to be synced with the 3d camera to follow every movement and to create the parallax effect.
One of the benefits is its use as a light source. Where green screen casts green shadows, the LED walls reflect the natural light from the background that is used at the time. But it has some hard time with recreating direct daylight.
Another benefit is that it makes location flexible. But camera movement is limited.
Where with green/blue screen most visual effects were done in post-production with virtual production most of the visual effects has to be done in the pre-production since the set needs to be ready for production. When the screens are not ready for the shoot, green screen replacements can be used.
Virtual production also solves a practical problem: the eye line. With predicting where the visual effects will be as an actor it can be hard to have the eyes on the same line as the direction where the object would be in post. The LED set will fix this problem.
StudioBinder. (2023, 17. April). Virtual Production explained — Is this the end of the green screen? [Video]. YouTube. https://www.youtube.com/watch?v=a25BMp5Z1QY