Perceptual%20biases%20in%20the%20interpretation%20of%203D%20shape%20from%20shading

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• Perceptual biases in the interpretation of 3D
  shape from shading
• Written by Baoxia Liu, James T. Todd
• Presented by Nick van der Poel

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Contents

• Introduction
• Experiment 1
• Results 1
• Experiment 2
• Results 2
• Discussion Conclusion

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Introduction
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Introduction

• How are the sign and magnitude influenced by
• Cast shadows
• Specular highlights
• Indirect illumination
• Occlusion contours
• What is the strength of the overhead illumination
• and global convexity bias?

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Experiment 1

• 7 subjects participated
• 96 conditions

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Results 1

• How do we determine the direction of illumination
• and the sign of curvature?
• Specular highlights
• Cast shadows
• Correct sign of curvature judgements was 56

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Results 1
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Results 1
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Results 1
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Experiment 2

• Occlusion contours

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Results 2
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Conclusion Discussion

• Cast shadows and specular highlights provide
  useful information
• Perceptual biases influence the sign of curvature
• Big differences between testsubjects
• Overhead illumination is a weak bias
• Large asymmetry in perceived depths