Tabula scalata facts for kids

Illustration from Nicéron's 1638 La perspective curieuse

Tabula scalata illustration in Le dve regole della prospettiva pratica (1583)

Imagine a special kind of picture that changes right before your eyes! That's what a Tabula scalata is. These are artworks made on a wavy or ribbed surface. They hide two different images. You can only see one image clearly at a time.

Each image appears correctly when you look at it from a certain angle. Most tabula scalata have images in vertical strips. This makes the picture seem to change as you walk past it. Some versions have horizontal strips. You would need a mirror above the picture to see the top image.

Sometimes, the two pictures in a tabula scalata are very similar. They might even match in shape and size. When you change your viewing angle, it can look like one image smoothly transforms into the other. This is a simple type of morphing effect.

There's also a version called a "triscenorama" or "tabula stritta." This one has three images! Two images are on the sides of slats. These slats stand in front of a third picture. The main idea behind these changing pictures is similar to old theater backdrops. It's also like modern Trivision billboards that show different ads.

What Does the Name Mean?

The name "Tabula scalata" comes from Latin. It was first used in 1646 by a scholar named Athanasius Kircher. The term can be roughly translated as "ladder picture." This name makes sense because of the ribbed or "ladder-like" surface.

In English, people have used many different words for these changing pictures. Some common terms are "perspective picture" or "anamorphic picture." However, these terms can be confusing. They are also used for other types of pictures. Some experts suggest that "anamorphic" should only describe flat pictures with a distorted view. "Turning pictures" is a more accurate name, but it is not used as often. Sometimes, people call them "double portraits." But this name only fits if both pictures show people. It doesn't cover all tabula scalata.

Where Can You See Them?

You might even have a tabula scalata in your pocket! The UK Pound Coin was updated in 2017. It has a small raised image that changes. It looks like a "£" symbol from one angle. From another angle, it changes to a "1." The Royal Mint, which makes the coins, said it was "like a hologram." But it is actually a clever tabula scalata!