The Bent Lines Illusion: It’s Reality That’s Skewed

William Gadea 07.11.2012

This post will circle back to animation, but first let’s talk about lenses and bent lines.

When I went to film school, we were taught about the properties of lenses: wide-angle lenses made spaces seem larger and objects seem farther away, they had great depth of field (meaning things in front of and beyond the point of focus stayed sharper), but be careful… they also distorted things.

I am here to tell you that wide-angle lenses do not distort things. Reality is already bent. It’s our minds that distort things by straightening them out.

Imagine that you are 50 feet in front of a skyscraper. Look straight ahead at the building and the lines on each side of the skyscraper are parallel. Now look up to the top of the skyscraper – the lines on each side of the skyscraper contract, pointing to a vanishing point up in the sky. How did a pair of lines that looked like they would never meet, suddenly start converging so strongly? The answer is that the lines curved on their way up the skyscraper.

Why don’t we notice this? Part of the answer is that although our field of vision is close to 180˚ we can really only focus on an area in front of us that’s about 40˚ wide. This means that when we tilt our head up to the top of the skyscraper, we only notice a portion of it at a time. But it’s also our brains helping us. In our minds we know the lines are straight so that’s how they seem to us, even though the lines are subtly curved.

Now let’s go back to animation. Say we want to create a point-of-view shot of a character looking up to the top of a skyscraper. How would we do it? We would create a piece of art like the one below and move it from field A to field B.

Tilt Up - Bent Lines Illusion in POV

Notice how the lines are straight in the initial and final part of the movement, but curved on the way up. It looks odd, but when animated, the curve will be hard to spot, just as it is in real life.

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William Gadea

William Gadea is the Creative Director and Founder of IdeaRocket. Follow him on twitter: @willgadea.
William Gadea
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