How do hobbits shoot tall people and short people?

Remember how to film Gandalf and the Hobbit in The Lord of the Rings? In addition to using body double, a dwarf, the giant panda also designed special equipment (such as a carriage with a gap in the front and rear seats) to create a tall wizard and a short Hobbit in the same picture by using the illusion of depth of field in human vision. Simple, but effective.

However, this setting does not work in 3D shooting, because the illusion of depth of field is only effective in 2D screens. Viewers wearing 3D glasses can easily perceive that the proportion of people in the picture is just different from the camera, so they can't establish different height impressions in their minds.

To solve this problem, we can only shoot the Hobbit actor and Gandalf separately, and then synthesize them into the same picture through post-production. Because the shooting angle and shooting distance are different, the final synthesized picture will also reflect the physical differences of different strange roles played by normal people.

However, this brings performance problems. In the performance of the Hobbit and Gandalf, because they were filmed separately, the air-to-air performance was too dull, resulting in a realistic picture of the body shape, and the performance of the characters might not be so sparkling.

Therefore, the team of Giant Panda (Peter Jackson) specially designed a set of solutions (see the figure below).

In this scheme, two sets of 3D photography systems are used to shoot at the same time, and different characters in the same opposite scene are located in two scenes about 50 feet apart, one is a real scene customized according to the size of real actors, and the other is a green screen scene decorated with key props that are reduced by 25%. Both systems have motion control systems to control the cameras. All actions of the MC system in the left scene (including camera azimuth movement, rocker arm and scooter movement) are recorded by the MC system and synchronously transmitted to the MC system in the right green screen scene, so as to ensure that the motion of the right camera is completely consistent and synchronized with that of the left.

On the right side of the green screen system, the camera lens is placed closer to the actor, so that the characters in the image obtained on the right side will occupy more space in the picture (and thus appear taller) under the same perspective. In this way, when the green screen background is removed by the software and combined with the real scene on the left, Gandalf will appear much taller than Bilbo and disproportionately larger than the furniture in the real scene.

The difficulty of green screen lies in the accurate matching and positioning of life-size scenes in the future. For example, Gandalf's actors put their hands on the table in the green screen, and finally they can't become hands hanging in the air because of the unbalanced proportion. To this end, the production team specially designed a set of devices called Pinger, which is similar to a laser protractor. It will mark the objects in the real scene on the left in the green screen scene on the right at a ratio of 25% smaller than normal. This will ensure the exact matching of the final composite image.

The actors who play opposite plays on both sides wear hidden earphones to ensure that they can feedback each other's lines in real time and ensure the emotional spark of the opposite play as much as possible.

Finally, the pictures shot and synthesized by the two systems in real time will also be displayed on the monitor in front of the director panda in real time, just like looking at the viewfinder of a single camera system.