Wednesday, 15 May 2013

Optical Illusions in RPGs

In a previous post I wrote about the Droste Effect, a form of optical illusion using recursion, which provoked an exploration of other illusions, particular those of a physical or architectural nature. 

Now I'm sure everyone is familiar with Indiana Jones and the Last Crusade and remembers the final Grail test where Indy has to make "The Leap of Faith" out into the chasm to find a hidden walkway.  This is a good example of a forced perspective illusion, the walkway is painted in such a ways as to  render it invisible from the only perspective that the hero can have, the ledge.

This limits your options in a collaborative group scenario, as either requires you to bottle-neck the party or limit the number of viewers to force the illusion to work. However, perspective can also be used to make something visible (or at least legible) from only a single point of view. In otherwords an Anamorphic Perspective, the word itself being derived from the Greek words 'ana' meaning back or again, and 'morphe', meaning shape or form.

Anamorphic Perspective in Art History

One of the more famous paintings to demonstrate this trick was "The Ambassadors" (Hans Holbein the Younger 1553). In this we can clearly see a strange random grey shape which floats at the bottom center of the image.
The Ambassadors (Hans Holbein the Younger, 1553)
If the painting is viewed at an acute angle from the left side (as demonstrated above) the strange grey shape resolves into an image of a skull. 

Many art historians have come up with explanations as to its symbolism, which is unsurprising as the painting contains many cryptic clues as to the identity of the two sitters, although my favourite is that Holbein did it to show off his skill as a painter.

The painting hangs in London's National Gallery and well worth a visit, if you can't and want to learn more, the curators have put together a few nice videos to explain the painting's symbolism and how Holbein might have achieved the effect.

At the same time Erhand Schön a prolific woodcut designer from Nuremberg was using the technique to hide naughty pictures in his art.  This example is held by the British Library.
Jonah and The Whale (Erhard Schön, 1537) containing the anamorphic Squatting Peasant (highlighted in red)

More Modern Examples

One of my favourite modern exponents of the technique is Felice Varini who uses striking geometric shapes painted on the walls of rooms and even on the outside of buildings.

Rettangoli gialli concentrici senza angoli al suoo (Felice Varini, Switzerland, 1997)

Here's a great example from Brusspup, which uses a sliding glass door and coloured paper.

So how the heck do I use this in an RPG?

Anamorphic Illusions can be simulated in RPGs in one of two basic ways, either:

Room as presented to players
In Plan View - By presenting presenting the players with a map of a room (either as a handout or as a battlemap) in which are contained several prominent architectural features. 

In the example below it would something like:

"Beyond the door lies an undecorated and austere looking 100ft square room with no exits.  Against each wall stands a large statue which appears to be pointing with it's right hand outstretched at a series of large urns which stand in front of the northernmost statue.  Each urn appears to be sealed shut with wax and is large enough for a man to climb inside.  On the front of each urn is pasted a label adorned with strange eldritch symbols".

Room with solution (in red)
The solution (if you spotted my deliberate misdirection) is that the statues are not pointing at the urns at all.  They are in fact pointing to a floor tile (red square) which if smashed will reveal a secret under ground tunnel.

You could of course allow the party members to make copious spot hidden checks to determine the true target of the pointing statues.  If they cross the red square whilst traversing the room to reach the urns, their footsteps will cause an echo in the tunnel below.

Or you could just fill the urns with unspeakable horrors and watch the party dash across the room to their doom.  Your game your choice.

As a Handout - One of the simplest types of anamorphic uses layers which need to be positioned above one another to produce the effect.  Consider the three images below, trace these out onto some semi transparent paper (such as grease proof paper) or print them on OHP paper.  Tell your PC's that they have been written on the finest almost translucent animal skin or that they are etched onto sheets of glass.

Handout AHandout BHandout C

Message is revealed when
the images are combined
Individually they don't really much, but when combined together they read "This is a Hidden Message".

It's best to keep the handouts square, as you should let them spend some time puzzling over each one before they get them in the right orientation.

This is a massively oversimplified example for a fantasy game.  In a modern or future game glass and other transparent materials are common place and the handouts should seem matter of fact.

I've been toying with the idea of presenting my players with some DNA Chromatographs where the little blobs spell out a message when overlayed.  Luckily the extent of our knowledge of biology or medicine is limited to CSI Miami, so the science of chromatography shouldn't get in the way of a good reveal.

On a Serious Note... Dwarves and other little people

Whilst writing this I discovered a real world application of an associated technology to produce a similar effect.  Lenticulars have been atound for years, you see them on stickers, movie posters, postcards, anything where you want to show movement, animation or to reveal a hidden image.

The Spanish organisation, Anar Foundation, has recently produced a poster campaign which uses lenticular printing to reveal a hidden message including the telephone number of an anti-child abuse help-line.  The lenticular is arranged so that the message is only visible to children (or people of children's height) and not any adults (or potential abusers) who may be accompanying them.  A great idea and I'm sure you'll agree a worthy campaign.

This technique is of course something you could use in a delve of an old dwarven (or other half person) stronghold.  The original builders may have left messages to their kin in the walls which are only visible to persons of dwarvish height.  These could be anything from simple sign posts, elaborate trompe l'oeil vistas or warnings about the trap a bit further up the corridor.


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