Let’s magnify

the critical

bit.

Edges are important

Inferring edges

Subjective contours

Read me…...

C O WC O W

C O WC O W

Shadow letters are Shadow letters are surprisingly easy to read.surprisingly easy to read.

http://www.techfak.uni-bielefeld.de/ags/ni/projects/cognitivrobot/eyetrack/eye_concept.html

Minimal shadow can give you faces

http://www.techfak.uni-bielefeld.de/ags/ni/projects/cognitivrobot/eyetrack/eye_concept.html

If you obey the rules

inversion

http://www.techfak.uni-bielefeld.de/ags/ni/projects/cognitivrobot/eyetrack/eye_concept.html

What is the problem here?

http://www.techfak.uni-bielefeld.de/ags/ni/projects/cognitivrobot/eyetrack/eye_concept.html

Weird color is no problem

But shadow must be darker

W h ic h g r a y l in e i s a l i k e l y

c o n t i n u a t i o n o f t h e b la c k

l i n e ?

g o o d b e t

n o t b a d

m a y b e

n o t l i k e l y

g o o d b e t

n o t b a d

W h ic h g r a y l in e is a l i k e ly

c o n t in u a t io n o f t h e b la c k

l in e ?

g o o d b e t

n o t b a d

m a y b e

n o t l i k e l y

WHAT IS THIS?

Does this seem likely?

This seems more likely

“Good continuation”

Depth Cues

From 2D-3D

Occlusion

Is this likely?

Size

Texture

Relative position (height in field)

Here is why it works

You don’t need to recognize the objects

Areal Perspective (haze)

The misty mountains far away

Linear Perspective

Vanishing point

Linear Perspective?

Where is the vanishing point?

Linear Perspective?

These local bits don’t add up

Linear Perspective?

These add up…ambiguously

ShadowsShadows

But where is the sun?

And let’s not forget

Stereopsis,Vergence,

andMotion parallax