chapter 3 _ object recognition

Korea University Dept.of Industrial System & Information Engineering User Interface Lab

Chapter 3 _ Object Recognition + 이선정

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Gestaltist appoach

Law of Pragnanz

“of several geometrically possible organisation that one will actually occur which possess the best, simplest and most stable shape “ (Koffka, 1935)

Perceptual Organization Perceptual Organization


e

Gestaltist appoach

- a. the law of proximity - b. the law of similarity

- c. the law of continuation

- d. the law of closure

- e. the law of common fate

a b

c d



Gestaltist approach

- figure- ground segregation

- a) Homogeneous display b) Heterogeneous display - grouping of perceptual elements occurs early in visual processing



Gestaltist approach – Contray evidence


a

b

c

Upright Upside down


Primal sketch : this provide a 2-dimensional description of the main light – intensity change in the visual input, including

2 ½ - D Sketch : this incorporate a description of the depth and orientation of visible surface, making use of information provided by hading texture, motion, binocular disparity, and so on

3 - D Model representation : 3 – dimensionally the way that is independent of objects and their relative positions in a way that is independent of the observer’s view point

Theories of Objection Recognition Theories of Objection Recognition

Marr’s computational theory



Biederman’s recognition by components theory

- consisting of basic shape or components known as “geon” (36 개 )



Five invariant properties of edges

- culvature – point on a curve

- parallel – sets of points in parallel

- cotermination – edges terminating at a common point

- symmety - versus asymmetry

- collinearity – points sharing a common line


Objection Recognition Objection Recognition

Viewpoint _ dependent & viewpoint _ invariant theories

- viewpoint invariant theory ease of object recognition is not affect by observer’s view point

- viewpoint dependent theory change in viewpoint reduce the speed and of accuracy of object recognition


Brain System in Object RecognitionBrain System in Object Recognition

Visual agnosia

- Apperceptive agnosia object recognition is impaired because of deficits in perceptual processing - Associative agnosia Perceptual processes are essentially intact object recogntion is impaired partly or mainly


Face RecognitionFace Recognition

Bruce and Young’s model

-Structural encoding

-Expression anaysis

-Facial speech analysis

-Directed visual processing

-Face recognition unit

-Person identify nodes

-Name generation

-Cognitive system



Interactive activation and competition model

WRUs = word recognition Units

FRUs = face recognition Units

NRUs = name recognition Unit s

PRUs = Person recognition nodes WRUs = semantic information Unit



Are faces special ? Yes! - something special about face recognition

1) Holistic analysis 2) Analysis by parts

Are faces special ? No! - why face appear special ?


Visual imageryVisual imagery

“Seeing with the mind eye”

-Mental imagery has been that it is very similar to perception

-Why do we not confuse images and perception? Mental scanning - mental rotation


Thank You

chapter 3 _ object recognition

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