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assoverwroughtAI and Robotics

Nov 6, 2013 (3 years and 7 months ago)

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INTRODUCTION

Applied Perception for Visual Computing

Jehee

Lee

A lot of slides stolen from
Aditi

Majumder

Instructors


Carol O’Sullivan


Professor, Trinity College Dublin


Sabbatical visit at SNU starting from Oct 2012


Computer graphics, Computer animation, Human
perception, Eye movements


Office/Phone will be available soon



Jehee

Lee


Professor, Seoul National University


Computer graphics, Computer animation, Human
movements, Biomechanics, Robotics


Office: 302
-
325


Phone: 1845

Course Introduction


Understanding and applying principles of human
perception



We are particularly interested in visual computing


Computer graphics, computer vision, virtual reality, image
processing, visualization, experimental psychology, neuroscience



Access and enhance computer
-
generated scenes,
animations, and virtual environments.



The course will be delivered via a combination of lectures,
guest speakers, and student presentations

Recommended references


Visual Perception from a Computer Graphics
Perspective, W. B. Thompson, R. W. Fleming,
S. H.
Creem
-
Regehr
, J. K.
Stefanucci
, CRC
Press.





Vision and Art: The Biology of Seeing,
Margaret Livingstone, Abrams.

Grading Policy


Course participation, presentation: 50%



Term project or term paper: 50%

What is Perception?


Sensory experience of the world around us



Involves


Recognition of environmental stimuli


Actions in response to these stimuli



Five senses: touch, sight, smell, taste, hear



Proprioception


A set of senses involving the ability to detect changes in body
positions and movements

You are easily fooled

Perceptual Process


Cycles of Environment, Perception, and Action



Continual


You do not spend much time thinking about the actual process



Unconscious, Automatic


Eg
) Transforming

light on your retinas into visual image

Perceptual Process

Perception

Recognition

Action

Environment Stimulus

Attended Stimulus

Stimulus on Receptors

Transduction

Processing

Knowledge

Perceptual Process

Perception

Recognition

Action

Environment Stimulus

Attended Stimulus

Stimulus on Receptors

Transduction

Processing

Knowledge

Environmental Stimulus


Anything in our environment that we can perceive



Can be anything we can sense


see, hear, touch, smell, taste, or


the sense of proprioception

Perceptual Process

Perception

Recognition

Action

Environment Stimulus

Attended Stimulus

Stimulus on Receptors

Transduction

Processing

Knowledge

Attended Stimulus


A part of the environmental stimulus



Focuses attention on this stimulus

Perceptual Process

Perception

Recognition

Action

Environment Stimulus

Attended Stimulus

Stimulus on Receptors

Transduction

Processing

Knowledge

Stimulus on receptors



The attended stimuli excites the receptors



For example


Visual stimulus formed as an image on the retina


Sound changes pressure to affect the ear drum



Note


We do not perceive the image on the retina


It is just one of the initial steps of the process

Perceptual Process

Perception

Recognition

Action

Environment Stimulus

Attended Stimulus

Stimulus on Receptors

Transduction

Processing

Knowledge

Transduction



Transformation of one form of energy to other



Environmental energy transformed to electrical energy



The image on the retina generates electrical signals in the
tens and thousands receptors of the eye

Photoreceptor cells

Perceptual Process

Perception

Recognition

Action

Environment Stimulus

Attended Stimulus

Stimulus on Receptors

Transduction

Processing

Knowledge

Neural processing



Neurons are elements of nervous system



Interconnected together



Processing of the electrical energy by the neurons while
they travel through them


This changes the electrical energy in various ways

Perceptual Process

Perception

Recognition

Action

Environment Stimulus

Attended Stimulus

Stimulus on Receptors

Transduction

Processing

Knowledge

Perception


Conscious sensory experience



Electric energy transforms in brain to some experience



Is this the end of perception?


Recognition and action are important outcomes of the perceptual
process

Perceptual Process

Perception

Recognition

Action

Environment Stimulus

Attended Stimulus

Stimulus on Receptors

Transduction

Processing

Knowledge

Recognition


Identifying the experience as something


Known


Similar to some experience before



Placing objects in meaningful categories



Recognition and Perception are two separate process



The Man who Mistook his Wife for a Hat


By Oliver Sacks


The case study of a man with visual
agnosia

Perceptual Process

Perception

Recognition

Action

Environment Stimulus

Attended Stimulus

Stimulus on Receptors

Transduction

Processing

Knowledge

Action


Goal of perception is to create action


Evolutionary reason for development of perception



Motor activities


It can be a major action, like running toward the subject


It can be as subtle as blinking eyes



Response to perception and recognition



Leads to


New attended stimulus


Whole cycle repeats

Perceptual Process

Perception

Recognition

Action

Environment Stimulus

Attended Stimulus

Stimulus on Receptors

Transduction

Processing

Knowledge

Knowledge


Affects


Processing, Perception
, Recognition



Identification from memory


Old knowledge


Recent knowledge

Cognitive Influences on Perception

Cognitive Influences on Perception

Cognitive Influences on Perception

Cognitive Influences on Perception

Gestalt Psychology


Gestalt (German)


Essence or shape of an entity’s complete form


A theory of mind and brain



Gestalt psychologists stipulate that perception is the
product of complex interactions among various stimuli


The whole is different than the sum of its parts


Contrary to the behaviorist approach to understanding the elements
of cognitive processes



There are principles (or heuristics) often referred to as the
“laws of perceptual organizations”

Images taken from http
://psychology.about.com/

Images taken from http
://psychology.about.com/

Images taken from http
://psychology.about.com/