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Lecture Series for Those Who Stay Home

World of 3D Optical Illusion

Many people are fighting against the new coronavirus, but I cannot do anything except for just staying home. So I decided to start this series of lectures of 3D optical illusion with the hope that they could entertain those who stay home. It is my pleasure if you could enjoy them. (Related links are here.)

One general remark is that seeing videos is quite different from seeing 3D objects directly. When we see objects directly, we can use two eyes and hence can understand the depth relatively easily. On the other hanc, seeing videos is essentially equivalent to seeing objects by one eys, because a video camera has only one lens center. Some of the illusions presented here donot occur when we see the objects directly. Anyway you may enjoy all of the illusions as long as you are watching the videos.

Lecture 1. Right-Facing Arrow
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Gallery of Facing-Right Objects

Lecture 2. Anti-Gravity Slopes

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Gallery of Anti-Gravity Slopes

Lecture 3. Height-Reversing Staircase

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Gallery of Height-Reversing Staircases

Lecture 4. Penrose Triangle

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Gallery of Anomalous Objects

Lecture 5. Circular Rectangle

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Gallery of Ambiguous Objects Made by Circular Rectangles

Lecture 6. Multiple Silhouette Objects

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Gallery of Multiple Silhouette Objects

Lecture 7. Height-Reversing Objects

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Gallery of Height-Reversing Objects

Lecture 8. Invisible Chicken

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Gallery of Partly Invisible Objects

Lecture 9. Ambiguous Cylinders

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Gallery of Ambiguous Cylinders

Lecture 10. Topology-Disturbing Objects

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Gallery of Topology-Disturbing Objects

Lecture 11. Card Marks Floating on a Mirror

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Gallery of Reflexively-Fused Objects

Lecture 12. Paper-Made Ambiguous Cylinders

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Gallery of Paper-Made Ambiguous Cylinders

Lecture 13. Ambiguous Tiling

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Gallery of Ambiguous Tiling

Lecture 14. Triply Ambiguous Objects

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Gallery of Triply Ambiguous Objects