Lecture on Depth Perception

Introduction

• Depth perception enables us to determine direction (forward or backward) and see the world in 3D.
• Our eyes and brain make instantaneous calculations to understand depth and distance.
• Depth perception is divided into two types: monocular cues and binocular cues.

Monocular Cues

• Definition: These cues require only one eye to judge depth and distance.

Types of Monocular Cues

1. Linear Perspective

   • Parallel lines appear to converge in the distance; known as the vanishing point.
   • Example: Train tracks, sidewalks, and streets.

2. Relative Size

   • Objects casting a smaller image on the retina are perceived as farther away.
   • Consistent object size helps judge distance.

3. Texture Gradient

   • Close objects have distinct textures and details that fade with distance.
   • Example: Brick details up close vs. smooth appearance at a distance.

4. Light and Shadow

   • Shadows indicate light source direction and object dimensions.
   • Example: Basketball's shadow indicating movement and distance from the ground.

5. Interposition (Overlap)

   • Objects blocking others are perceived as closer.
   • Example: A tree blocking a car suggests the tree is nearer.

6. Aerial Perspective

   • Distant objects appear blurrier and lighter in color.
   • Example: Cliffs fading into the sky.

7. Motion Parallax

   • Objects at varying distances appear to move at different speeds when in motion.
   • Example: Median strip appears fast vs. distant trees appear slow.

Binocular Cues

• Definition: These cues involve both eyes to judge depth and distance.

Types of Binocular Cues

1. Convergence

   • Eyes converge closer together as an object approaches, signaling proximity.
   • Eyes diverge as an object moves away.

2. Retinal Disparity

   • Each eye sees a slightly different image; brain combines them for a clear picture.
   • Example: Different views from left and right eyes create a complete image.

Conclusion

• Both monocular and binocular cues are crucial for depth perception.
• They allow us to see and interpret the world in three dimensions.