What is "The Pepper Ghost" effect?

Question

I heard they use this trick on all of Disney's Haunted mansion attraction. But how do they do it?

Answer 1

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Pepper's ghost is an illusionary technique used in theatre and in some magic tricks. Using a plate glass and special lighting techniques, it can make objects seem to appear or disappear, or make one object seem to "morph" into another.

In order for the illusion to work, the viewer must be able to see into the main room, but not into the hidden mirror room. The edge of the glass may be hidden by a cleverly designed pattern in the floor. Both rooms may be identical mirror-images; this approach is useful in making objects seem to appear or disappear. This effect can also be used to make an actor reflected in the mirror appear to turn into an actor behind the mirror (or vice versa). This is the principle behind the Girl-to-Gorilla trick found in many haunted houses. The mirror room may instead be painted black, with only light-colored objects in it. When light is cast on the objects, they reflect strongly in the glass, making them appear as ghostly images superimposed in the visible room.

The world's largest implementation of this illusion can be found at the Haunted Mansion and Phantom Manor attractions at several Walt Disney Parks and Resorts theme parks. Here, a 90 foot long scene forms a single Pepper's Ghost effect. Guests travel along an elevated mezzanine overlooking an empty ballroom. Animatronic "ghosts" animate out of sight in black rooms beneath and above the mezzanine. The reflections in the glass create the appearance of three-dimensional, translucent ghosts that swarm through the ballroom. This use of the effect is notable for two other reasons; it uses a vertical pane of glass that is parallel to the scene and the reflected objects are located both below and above the viewers.

An example which combines the Pepper's Ghost effect with a live actor and film projection can be seen in the Mystery Lodge exhibit at the Knott's Berry Farm theme park in Buena Park, California.

Answer 2

i'm not quite syre.