The Moon Terminator Illusion

TL;DR

Foreshortening and perspective illusions play tricks on our visual perception, affecting the way objects appear in our field of view.

Transcript

Hey, Vsauce. Michael here. This is called the dolly zoom effect and the optics that make it possible are also responsible for what's called the moon terminator illusion. A terminator is the line between an illuminated and dark side. Light arrives perpendicular to the terminator but it doesn't always appear to. Maybe you've noticed this before. When... Read More

Key Insights

• 🫵 Foreshortening is a visual phenomenon caused by the distance between an object and the viewer, making objects appear smaller or distorted.
• 👻 Our brains adjust for foreshortening and maintain subjective constancy, allowing us to perceive objects accurately despite their distorted appearance.
• 🏑 Perspective illusions, such as the star field or hallway illusion, can trick our brains into perceiving movement or speed differently based on the position of objects in our field of view.
• 🪛 The Renaissance shift towards realistic perspective was driven by cultural interests and the desire for objective representation, rather than a sudden advancement in artistic abilities.

Questions & Answers

Q: Why does the line between the Sun and the Moon appear curved when it's actually straight?

The curved appearance is caused by foreshortening, where our brains assume equidistance in the absence of perspective clues from the sky.

Q: Why do objects that are far away appear smaller?

Objects that are further away have a smaller visual angle, making them appear smaller in our field of view due to foreshortening.

Q: How does parallax help us perceive depth?

Parallax is the change in visual angle as we move towards or away from an object. It allows us to understand depth by observing how objects appear to move relative to each other.

Q: Why did it take so long for artists to incorporate realistic perspective in their paintings?

The shift to mathematically formal perspective was influenced by cultural interests and the desire to imitate reality objectively, rather than a sudden increase in artistic intelligence.

Summary & Key Takeaways

• The dolly zoom effect and the moon terminator illusion are both caused by the same optics that create foreshortening.

• Our brains use previous experience and perspective clues to adjust for foreshortening and maintain subjective constancy.

• Foreshortening affects how objects appear in our field of view, and our brains sometimes incorrectly perceive changes in slope or size due to this distortion.