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

2. Contents Introduction Experiment 1 Results 1 Experiment 2 Results 2 Discussion & Conclusion

3. Introduction

4. 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?

5. Experiment 1 7 subjects participated 96 conditions

6. 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 %

7. Results 1

10. Experiment 2 Occlusion contours

11. Results 2

12. 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