Category Archives: illusions and aesthetics

The Oxford Compendium of Visual Illusions

I’ve copied this beautiful demo (with small changes) from one by Stuart Anstis, who is one of the world’s leading and most prolific researchers into illusions.  His website includes a page of great movies, including this one.  Whilst the yellow circles are visible, we tend to focus locally on the pairs of spheres, each pair orbiting a central point.  But without the circles, loosely fixate the central blob, and though the movement of the spheres remains just the same, they appear to re-group into a more global view, of two pulsating, intersecting circles of spheres.

I came across Stuart’s movie amongst the many web pages of figures and demonstrations that accompany a once-in-a-generation, landmark publication, the Oxford Compendium of Visual Illusions.  (It’s not cheap – check the price before ordering!).  But that’s because it’s HUGE, with some 800 pages.  Almost all the leading researchers in the field worldwide have contributed, with essays on the history of visual illusions, up-to-the-minute, detailed discussions of a comprehensive range of illusions and effects, and philosophical essays on whether the word illusion is really the right term to describe them.

 

Trompe (or Trump?) l’oeil

In the era of Trump it’s got harder to tell reality from illusion, but here’s a ceiling from about 300 hundred years ago that shows a real magician in the illusion line at work.  The inside of the dome  – everything inside the gold circle – looks as if it extends upwards, but it is just painting on a flat canvas.  It’s an example of so-called trompe l’oeil, French for deceive the eye.  I don’t know why we use a French term – it was never a French speciality.

Some time back I posted about the brilliant trompe-l’oeil by Andrea Pozzo on the ceiling of a church in Vienna, painted a little over three hundred years ago. The photos here show a ceiling in the UK painted thirty years later, by an artist following where Pozzo led the way.  It’s in the main entrance hall of a mansion called Moor Park, in the West London suburb of Ruislip, painted in the 1730s. The mansion is now a posh golf club, so it’s not usually open to non-members, but it’s visitable by arrangement, http://www.moorparkgc.co.uk/

The painting of the hallway was done by a trio of Italian specialists in architectural decoration – Giacomo Amiconi, Gaetano Brunetti and Francesco Sleter.   I’m not sure whether Brunetti or Sleter painted the illusory dome.  They’re not well known.  Painting this kind of thing was quite lucrative, but didn’t make you a star in the art world of the time.

Like the dome painted by Pozzo, the illusion in Moor Park is amazingly successful – but only from one viewpoint.  As you can see in the lower photo, from everywhere else the dome looks wonky.

Digital Kaleidoscopes – post no. 1

Everyone loves a kaleidoscope, particularly the ones with a lens at the end, so that as you look through them whilst sweeping the kaleidoscope around, the view becomes a dazzling starburst pattern.  (I find Nova Magic Marble kaleidoscopes are inexpensive ones for kids that work pretty well).   However, real-world kaleidoscopes can only tile the visual field with a limited repertoire of geometric shapes – typically triangles. Digitally we can tile with any shape that will tessellate – that is, fill the plane by repetition without gaps or overlaps. As with real-world kaleidoscopes with a lens at the end, each tile can enclose a streaming segment of a visual scene, if you are handy with graphics and 2D animation packages.  If that all sounds a bit puzzling, I think the movie will make it clearer.

But then there’s a surprise!  Illusions of movement may appear, dependent on figure/ground effects.

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Mamluk Interlace

MamlukPair

I’m fascinated by the way that spectacular aesthetic effects often seem to involve bamboozling our everyday strategies for making visual sense of the world.  This is a beautiful example, a detail of interlace decoration on a 14th century (Western dates) Mamluk Period door in the Louvre from the Al-Maridani mosque in Cairo.  (I’ve shown other examples of a role for bamboozled perception in aesthetics in an earlier post, and in the Illusions and Aesthetics category to the right).

As you can begin to see in the image, where I’ve combined the interlace pattern on the door with a schematic analysis of its reflection, the interlace we see in the door is a segment of a rosette pattern that repeats across a wider field.  But that’s not obvious at all when you just see the door.  The artist has not emphasised the lines of the design, but rather the infills – stars and other little geometric tiles.  We’re distracted from grasping the overall geometry by all the assertive, enclosed shapes, with their heavy outlines.  And the overall shapes that do jump out for me are the beautiful curves that run from top to bottom of the image, which also distract attention from the hexagonal geometry of the pattern.  For more analysis of the pattern and the fabrication of the doors, see below, but first, here’s the whole door.

Mamluk Door

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AHA!

Rex Whistler heads from AHA!

Some of the best of all illusions in the tradition of rotating heads were designed for advertising in the 1930’s by British artist Rex Whistler – you really have to take a second look to convince yourself the lower faces are just rotations of the upper ones. He was sadly killed in action in World War Two, but the heads were collected in a book of 1979, AHA.  He got the idea from some seventeenth century engravings, (reproduced below), which had first appeared in 1671 in a book by polemicist Pierre Berault. The Western, Christian world at that time was riven with hatred between Catholics and Protestants, and these images are an anti catholic salvo, showing a Pope (left pair of roundels below) and a cardinal (right pair of roundels below) transforming into devils with rotation.

I found these details in two editorials about rotating heads for the journal Perception, by perceptual scientist and artist Nick Wade and colleagues.  Check them out for lots more info and images. One is from 2003, the other from 2005, and they are the most authoritative source of information on rotating heads generally.

17th Century and Roman rotating heads

In the 2003 paper Nick Wade also shows one of the oldest rotating heads we know, a second century AD Roman beaker, shown to the right above. It was spotted by Christine Wade in the Hungarian National  Museum in Budapest.  (Photo © Christine Wade)

There are earlier posts on this site about rotating heads, one with Father Christmas turning into playwright Henrik Ibsen, another about a tale of nightmare in a hotel. And if your appetite for this stuff is insatiable, look at the more recent post on cartoonist Gustave Verbeek.

Cockatoo coming through

One of my favourite René Magritte paintings is Carte Blanche. (There seem to be problems linking to an image of that – I guess copyright related – but just put that title into an image search).  I’ve two earlier posts that play on the same effects – an image for Halloween and a classical scene.   I’ve always wondered if the effect would be even stronger and stranger in an animation.  So here it is.

Usually an area of the visual field within an outline, or more or less bounded by an outline, is either an object or an aperture.  (One of my earliest posts on the site is also about that).  We are so good at not getting those mixed up in everyday vision that when they get mixed up in a picture, like the Magritte painting or my examples, the effect is strangely disconcerting.

Thanks to Edweard Muybridge for the loan of the Cockatoo.

Stern, Smiling and Radiant Buddha

In this wonderful image of the Buddha from Bagan, Myanmar, facial expression changes from stern through smiling to radiant as the figure is viewed from increasing distance.  According to my friend Eddy Keon, the highest status members of the temple audience, along with temple officials, would have stood closest to the Buddha and therefore have experienced him at his sternest, whilst his radiance increased with the poverty of the viewer, banished to the back of the crowd.

The figure is the Kassapa Buddha, one of four Buddhas in the Ananda Temple, Bagan, Myanmar.  The city was the capital of the ancient Pagan kingdom, built, along with the temple and this figure of the Buddha, eight hundred years ago.

 The left hand and centre photos are from the brilliant travel blog of Forrestwalker.  The right hand image was taken by Eddy Keon.  His photo is so beautiful, here’s the whole thing.  Eddy hopes to use his pictures to support a hill village school in Myanmar.

 

Gustave Verbeek

Gustave Verbeek cartoon

About a hundred years ago one of the most popular newspaper comic-strip artists in America was Gustave Verbeek.  He contrived whole pages of pictures telling cartoon stories, which showed one sequence of scenes when viewed one way up, and the following set when turned upside down.  His best known adventures were those of Lady Lovekins and Old Man Muffaroo, each of them, as in the scenes above, always the inverse of the other.  His stories are so crazy and his drawings so imaginative that it can take a moment to realise one scene really is the exact inverse of the other.   His imagery is surrealist – long before surrealism emerged with artists like Salvador Dali in the establishment art world.

His cartoons have recently been reprinted (not cheap!)

Verbeek was developing an earlier tradition of rotating heads illusions, in which a head has one identity one way up, and another upside down.  See my first earlier post of that, with an animation, and another example with Santa turning into playwrite Henrick Ibsen

Native Canadian Ambiguous Art

Depending how you see it, this panel either shows two killer whales looking at one another in profile, or a bear looking at you head on – the killer whales’ fins top centre become the bears’ ears.  And then the killer whales’ tails centre bottom become the mouth of a third creature, probably a frog, but the carving was never finished, so only its eyes are carved.

The panel is probably about a hundred years old, and is about five foot wide (1.6 meters or so).  It’s not known why it was never finished, but in the tradition of north west coast Canadian carving, the decoration on the killer whales would have been carved into deeper relief, not just sketched out on the surface.  Nor is it known from just which ethnic group in North West Coast Canada it comes.

However in the mythology of all the groups of that area, such as the Haida and the Kwakuitl, transformations of one creature into another are part of the scheme of things.  That includes transformations by hunting and eating, which were traditionally understood as sacred activities.  So what we see here is not just a visual game, but has spiritual meanings.

For more on that see our earlier post on ambiguous patterns, and other posts in the Illusions and Aesthetics category.

The panel is in the reserve collection of the Manchester Museum.

Cheating with tessellations

Tessellations are patterns whose repeat motifs fit together like jig-saw pieces, with no gaps and no repeats.  For an introduction, see our earlier animation. They can be abstract patterns, but the most intriguing are the ones devised by tessellation maestro M.C.Escher in the middle of the last century, which show representational motifs, such as animals, as tessellating patterns.

Designing abstract patterns that tessellate successfully is just a matter of getting the hang of some rules.  Discovering representational motifs that tessellate is much, much harder.  There are no procedures, or none that I know anyway.  It’s all trial and error, mostly error for me, and really hard!  Escher was brilliant at it.  My efforts are pretty feeble.

But fortunately, you can at least include representational motifs within your tessellations with a little trickery.  The pattern above, based on Leonardo’s famous Vitruvian Man, is an example.  The secret is to use segments of the outline of the representational motif for part of the outline of the tessellating pattern cell.

You do need to be up to speed with making abstract tessellations, and also pretty expert with Photoshop or an equivalent graphics package.  But if you’ve reached that point, or are just curious, here are stages in the development of the pattern shown above….

 

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