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확률 변수 및 확률과정의 기초

2005 05 16

Natural-scene geometry predicts the perception of angles and line

orientation

Catherine Q.Howe and Dale Purves

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확률 변수 및 확률과정의 기초

INTRODUCTION

Fig. 1. The misperception of angles and line orientation

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확률 변수 및 확률과정의 기초

One possible explanation: Fundamental ambiguity of geometrical stimuli

- visual system copes with this biological quandary by generating percepts according to the probability distribution of the physical sources of the retinal images.

To test this idea laser range scanning to obtain

a database of natural scenes

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확률 변수 및 확률과정의 기초

Materials and METHODSThe Range-Image

LMS-Z210 3D laser scanner

103 wide-field images: 25 fully natural scene, 78 scenes that included human constructions

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확률 변수 및 확률과정의 기초

~1000000 different 2D image projections

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확률 변수 및 확률과정의 기초

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확률 변수 및 확률과정의 기초

Determination of the Physical Sources of Angles

The stright lines extracted from the database are sets of points that form straight lines by geometrical criteria, not luminance contrast(edge) criteria.

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확률 변수 및 확률과정의 기초

Sampling with Geometrical Templates

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확률 변수 및 확률과정의 기초

(c1R1 + c2R2 + c3R3 + c4R4)/(c1 + c2 + c3 + c4)

- The total number of valid sample: ~4.4*10^6

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확률 변수 및 확률과정의 기초

RESULTSThe probabilistic approach to rationalizing angle perc

eption Hypothesis: visual perceptions of angles and line orientations ar

e generated according to the probability distribution of possible physical sources

The subtense of a particular angle should be predicted by the rank of that angle in the accumulated past experience with angles

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확률 변수 및 확률과정의 기초

Probability distributions of the physical sources of angles

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확률 변수 및 확률과정의 기초

Predicting the Perception of Acute and Obtuse Angles

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확률 변수 및 확률과정의 기초

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확률 변수 및 확률과정의 기초

Explanation of the Tilt, Zoellner, and Hering illusionsFig.1

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확률 변수 및 확률과정의 기초

Discussion To generate percepts that accord with the

probability distribution of possible physical sources provides a way of maximizing the chance of successful visually guided behavior

Neural mechanisms – the empirical associations between intersecting line projections and their sources

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확률 변수 및 확률과정의 기초

Conclusion The advantage of the probabilistic strategy is

that the relationships among objects in the physical world are preserved in perceptual space, ensuring that the perceptions of the observer provide the most beneficial guide to action in the face of the inevitably uncertain meaning of retinal images.