Form Perception - Employees Csbsju

The world as we see it….

….. so far.




The Neural Picture

Rods and cones

Ganglion cells (M cells, P cells)

LGN (
magnocellular

tract,
parvocellular

tract)

PVC (striate cortex)

Simple, complex,
hypercomplex
)

The world as we see it….

….. so far.

The Visual Picture

•
Simple features

•
Low level vision





Affordances….

What information is important to glean from the
environment?

How do I learn about the objects and events in
the environment that I inhabit?

ASSIGNMENT FOR NEXT CLASS MEETING

Machine Vision

Limits of machine vision

Limits of simple features

Limits of low
-
level vision

Mid level vision

What intermediate processes intervene between
the collection of basic features and the
understanding of objects?

How do we “parse” a scene?

AI definition
–

interpreter, compiler of data in a
context of ambiguity

Top down, bottom up types

Why is the visual scene not
like a bar code?

Stimulus variation

Differences in illumination

Multiple edges, lines

Incomplete boundaries

Multiple interpretations

Observer variation

Viewpoint
–

accidental or otherwise

How do we begin to extract meaning
from the messy visual array?

How do we use and choose from the features at
hand?

On what basis do we “decide” what
interpretation to “go with”

A final comparison of machine and
man (and, of course, woman too)

Effort

Acquisition of skill

Flexibility of the rules

Pragnanz

What is available in the
stimulus?

Edges

Textures

Figure
-
ground

Parts and wholes


Edge detection

Sum up the simple features?

___ + ___ + ___ = _________

Problems

Variation in illumination

Incomplete forms

Illusory contours


Gestalt rules of
organization

A bit of history…..

Rules of organization

Good continuation

Edge detection

Gestalt rule of good continuation

Edge detection

Gestalt rule of good continuation

Gestalt rule of occlusion

Edge detection

Gestalt rule of good continuation

Gestalt rule of occlusion

Closure


Perceptual Committees

Good continuation VS Occlusion



…..
a
nd the winner is?

What is available in the
stimulus?


Edges

Textures

Figure
-
ground

Parts and wholes


Texture Segregation
(texture
segmentation)

Similarity


Texture Segregation
(texture
segmentation)

Similarity

Proximity


Texture Segregation
(texture
segmentation)

Similarity

Proximity

Parallelism and Symmetry


Texture Segregation
(texture
segmentation)

Similarity

Proximity

Parallelism and Symmetry

Common region


Texture Segregation
(texture
segmentation)

Similarity

Proximity

Parallelism and Symmetry

Common region

Connectedness



What is available in the
stimulus?


Edges


Textures

Figure
-
ground

Parts and wholes


Figure Ground

What is the stimulus?

What is the background?

Surroundedness

Size

Symmetry

Parallelism

Extremal

eges

–

shading

Relative motion

Extremal

edges