Sergeant Pepper? Dr Pepper? Peppa Pig? No, in this post we’re talking about Pepper’s Ghost, the illusion of projecting an off stage person on to the stage to appear in front of the audience. This was first demonstrated by John Henry Pepper in 1862, driving a trend for 19th century ghost-themed plays, and remains in use today in theme parks, museums, and concerts featuring artists from Elvis to Tupac. These modern realisations are sometimes erroneously called ‘holograms’ as they suggest that freestanding 3D images can be created floating in space, but of course they are only illusions of holograms in much the same way that the original Pepper’s Ghost created the illusion of a ghost.

My colleague Dr Paul Tennent at The University of Nottingham’s Virtual and Immersive Production Studio has been applying Pepper’s Ghost to the more close-up, human scale experience of avatars by projecting video and animations onto an unusual personal podium. Physically, the podium features a configurable inverted pyramid of transparent screens, mounted onto a wooden plinth which hides a projector that projects images onto them from below, with the screens set at the right angle that the image appears to float above the podium, though in the example below we used only a single screen to maximise the size of the image. Digitally, the images can be video of a person or object, captured using green screen technology so that the background can be removed, or animated graphics.

Carolan was delighted to be invited to give it a try. Paul’s idea was to create a jam session in which visitors to the studio could play along with Carolan, adding their own parts to a growing collective jam. We chose twelve-bar blues as a widely recognised structure that would be familiar to many musicians. The first stage was to visit the studio and record a backing track on video.

This was then processed and arranged to appear as a pepper’s Ghost on the plinth. Here’s a first attempt of Carolan (and Steve) to play along with themselves.

And here’s second of visiting classical guitarist Stewart French (www.stewartfrench.com) improvising a response. Stewart has toured as a soloist with the Royal Philharmonic Orchestra and is the founder of the Fly On The Wall production company which has seen him work with the V&A, Naxos, Apple Music and many others. This was his first time meeting Carolan – real or ghostly…

It’s interesting to see how Stewart obviously looks at Carolan/Steve, but they of course do not return his gaze. Much as motional captured actors have to learn to act to invisible props and characters, it would have been good to have recorded the original green screen to give the illusion of occasionally looking at future players.