Smoke and mirrors

June 18th, 2008

Imagine an ethereal figure forming as a vaporous, shaky apparition in the display before you, empty one minute, haunted the next. The figure may then turn and speak to you, walk around, or it may fade and vanish as quickly as it came.

There may even be a whole cast of historical “ghosts”, wandering up and down chattering to each other, enacting a story or scene from the past before disappearing into thin air.

It sounds a bit like Hollywood magic dust, but the technique of such special effects was developed in the mid-19th century and has been used ever since. At its most basic, ghosts can be conjured with little more than bright lights, a “stage” set and a piece of glass or a special reflective plastic screen.

This set-up was pioneered by the Victorian inventor Henry Dircks in 1862, but was adapted for use on the stage, and popularised by John Henry Pepper, earning it the name Pepper’s Ghost (despite Pepper’s repeated credit to Dircks).

There are a number of smoke-and-mirror-type special effects that can work effectively in museums, but the Pepper’s Ghost is something of a favourite among designers and curators. And if the aim of a display is to stimulate learning using engaging spaces, then a little theatrical magic can go a long way.

With careful planning, museums and historic sites can put this versatile technique to good use, creating anything from a simple scene that dissolves into another, as in the Marq, the archaeological museum of Alicante, where an alcove in a mosque is Christianised with a crucifix (see MP27, p16-21), to a complex interaction of filmed “ghosts” and live actors, as seen at the Abraham Lincoln Presidential Library and Museum in Springfield, Illinois.

Recent examples of Pepper’s Ghosts in the UK include “visitations” by the tennis star John McEnroe at the Wimbledon Lawn Tennis Museum, and the football manager Alex Ferguson at the Manchester United Museum, both appearing “live” before visitors’ eyes.

“The ‘ghosts’ can interact with the set and objects, which means you can make much more of the space. With straight video there’s much less emotion or passion because we all watch telly all the time,” says Chris Mather, the director of Mather & Company, which designed both exhibitions.

How do they do it?

The basic trick of Pepper’s Ghost is in making a reflection on a piece of glass or plastic screen appear as if it were really part of a physical scene or room set. The reflection itself could be anything: a static person or object, or video footage showing moving characters or objects. And it can be turned on and off to give the appearance that apparitions are emerging from thin air.

The illusion is achieved by placing the glass at 45 degrees across the main room or set, while off to one side (or above or below) there is a second, hidden space containing either the video projection or a replica set mirroring the first, depending on the effect you are after.

What is important is that the glass is invisible to the viewers: they must look straight through it into the room or model without realising it is there. Then, when bright lights are shone on the hidden room, or the video projection is turned on, the contents of this hidden space show up as reflections in the glass.

The effect is then manipulated by turning the projection or lights on and off, causing the reflected “objects” to magically appear and disappear inside your exhibit.

From this type of set-up, many embellishments can be made to create more complex illusions. Characters might interact with their environment, walking through doorways, sitting at desks, leaning on counters or even picking up “ghost” items and moving around with them. Alternatively, ghost objects may be made to transmogrify into something else by gradually fading between different projections.

In more elaborate versions of the technique, Pepper’s Ghosts have been used in tandem with live actors to unfold whole narratives in fully theatrical productions. The Ghosts of the Library at the Abraham Lincoln Presidential Library and Museum was created by BRC Imagination Arts, using its Holavision technology.

In the library misty spectres of historical figures, including Lincoln, share the stage with live performers. Although the design company keeps the details of just how Holavision works under wraps, it is basically a high-tech version of Dr Pepper’s original Victorian ghost.

Projections of video placing the moving image of an actor in a setting are ideal for museums and heritage sites as they can place a storyteller in an object-filled set to deliver a narrative in a powerful and immediate way. This is more complicated to put together than a straightforward Pepper’s Ghost reflection or transition, however.

A good example can be found in the Singapore Discovery Centre, designed by Neal Potter Design Associates. It features a simple transition set-up to achieve the unexpected: a visitor standing inside a pod disappears from the point of view of the other visitors.

The installation is part of an exploration of stealth technology. “The reflected image showed a visitor ‘inside’ the main set pod, which was really empty. So when the lighting changed the visitor seemed to disappear,” explains Potter.

Another example of a transition can be found in the Tullie House Museum and Art Gallery in Carlisle, where a full-size skeleton morphs into a Roman soldier in full regalia and back again, stepping through three phases of transition.

The exhibit, created by RFA Designers, uses the technique to rewind the clock from archaeological relic to lifelike military figure. “It makes the point visually in a really simple and effective way,” says Richard Fowler, a director of RFA Designers.

Conjuring the ghost

In essence, Pepper’s Ghost is a trick of lighting, so a precise lighting set-up is essential. Whatever is bright in the hidden area will reflect in the glass, while the dark areas will not show up, leaving the glass transparent. Careful control of your lights is the key to attaining the magical effect.

If you are using a video monitor or projection to place moving images into the main set then they must be set against a black background to prevent anything else from showing up in the glass. This also means that the actors or objects in the film must be recorded against a black background so they are the only things creating a reflection when the video plays.

You can also determine how far into your main set the image will appear to the viewer. The apparent distance behind the glass is the same as the distance between the glass and the object in the hidden space, so moving the projections or objects in the hidden room further from the reflective glass plane will place them deeper into the main set, and vice-versa.

Although these principles are fairly simple, experienced designers are adamant that the set-up has to be just right to make the Pepper’s Ghost really effective. The quality of the final images may depend on the quality of the filming, the lighting and the set up of the reflective screen and projections.

If you do not want your ghosts to be too ghostly, but appear instead as solid, life-like figures, shoot in high-definition video, says Chris Mather. “You’ve got to get the balance between lighting and reflection exactly right. There are some horrible ones around,” he warns. “Some look like ghosts but aren’t supposed to. For John McEnroe and Alex Ferguson we wanted them to look as solid as possible,” says Mather.

Planning and scripting

If you are looking to use recorded actors to populate your space then planning and scripting are crucial. The people and objects in the film must overlay precisely with the objects in your set when they appear as reflections.

So if an actor leans against a (black and hidden) counter in the recorded film, its location must match exactly the location of the real counter in your model. If somebody walks through a doorway in the model they will have to walk through a correctly placed mock doorway in the filming so they are obscured at the right moment in the reflection.

Lighting in the filming is also important. If an actor is to move through rooms in your set that have different lighting conditions, then the lighting used in the filming will need to change accordingly so their ghostly figure fits naturally in its environment.

Another embellishment is to include moving parts, such as a drawer or door, in your set or model, which can be opened during the sequence. To do this, the filmed actor must mimic the action, and the film must be synchronised with a mechanically moving part in your model so the character appears to open the real, physical drawer.

Variations on these ideas abound. But this requires a lot of planning, as Robin Clark, a director of Land Design Studio explains: “The timings are very important because it’s all got to look natural.” Script writing is vital not only to make sure the filmed action fits seamlessly into your set, but also to make sure that the correct information is being presented to the audience.

The wow factor is one thing, but curatorial or interpretative objectives must also be met. Chris Mather agrees: “I would say in order of importance it’s scripting, then acting and then equipment.”

For a video-based Pepper’s Ghost there will be quite a few people involved. Your designers should be able to script and direct the sequences, or they will bring in a scriptwriter to do so. They could also create the sets and models, if you cannot do that in-house.

Actors will be needed to play the roles and a video production company will handle the filming. The designers will then oversee the installation of the set, reflective screen, projection equipment and lighting.

All this means that Pepper’s Ghost may not the cheapest design route to take when planning an exhibition. But a basic version can be done without any real specialist equipment (models and sets, objects, glass or screen, lighting, projector or monitor and power sources) and at a fairly modest cost. From there, increasing the complexity and the quality of the models and film will raise the cost.

A Pepper’s Ghost is an undeniably captivating and versatile effect, with its own timelessness. New technologies have merely refined it.

This article was written for Museum Practice, Summer 2008.

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