本文介绍法国裔美国发明家奥利维尔·雷东创作的五种视错觉，包括内克尔立方体和罐头错觉，解释其视觉原理和制作方法。
A magician reveals his visual tricks
Earlier today I posted five optical illusions by Olivier Redon, a French-American inventor. Here they are again – with demonstrations of how he created the effects.
Three of the images are inspired by the Necker cube, a two-dimensional drawing of a cube that can be understood in two ways: either with the bottom left face at the front, or the top right face at the front. Once your eyes settle on one interpretation, it is hard to see the other.
Here’s an image of a can. But what are you actually looking at?
The illusion convinces you that you are looking at the outside of a complete can, when in fact you are looking an inverted internal segment of can with the top stuck on upside down. The eyes see the shape as curved outwards, when in fact it is curved inwards.
The image at the top of this article shows the two pieces you need to create the illusion: the top disc, and the side section, which are then fitted together.
This is not a red box! What is Redon actually holding in his hand?
Amazingly, the cube is two pieces of cardboard…
As with the Necker cube, once you see the faces as sticking out (or in), it is very difficult to see tham as sticking in (or out).
The still images don’t do this illusion justice. The video is quite remarkable. It is hard to believe your eyes.
This iPhone image is of two dinosaurs that are the same size. How did Redon take the image?
This illusion plays with lines of perspective. All you need to do is take pictures of the dinos at both a horizontal and a vertical angle.
This is a portrait of Redon and his daughter. How was it taken?
This looks like a cube with transparent sides. But what is it?
This one is the Necker cube again. The three squares with writing on are not the outward faces. They are the inward faces!
I hope you enjoyed these illusions. I’ll be back in two weeks.