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Understanding Shape from Shading in Diffuse Lighting: The Dark Means Deep Debate

This presentation by Michael Langer and Heinrich Bülthoff at the European Conference on Visual Perception explores the concept of shape from shading under diffuse lighting conditions. It questions the common assumption that "dark means deep" in visual perception. Through experiments and computational modeling, the authors demonstrate that the human visual system employs an accurate physical model based on the angle of the visible light source rather than relying solely on point source models. The findings challenge traditional views on how we interpret shading and depth in our visual field.

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Understanding Shape from Shading in Diffuse Lighting: The Dark Means Deep Debate

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  1. Michael Langer Heinrich Bülthoff NEC Research Institute MPI for Biological Cybernetics Princeton, NJ Tübingen, Germany Shape from Shading under diffuse lighting: does dark mean deep? Presentation at the European Conference on Visual Perception, Oxford, U.K, August 1998

  2. SFS on a Sunny Day  L  N(x)   I(x) = N(x) L

  3. SFS on a Sunny Day   I(x) = N(x) L

  4. SFS on a Cloudy Day  (x)

  5. SFS under Diffuse Lighting      I(x) N(x) L dL  (x)  (x) = angle of visible light source

  6. SFS under Diffuse Lighting

  7. Hill or Valley ?

  8. SFS under Diffuse Lighting Does Dark Means Deep?

  9. Does Dark Means Deep? local intensity maximum

  10. intensity anti-correlated correlated _ + depth _ + Height-Intensity Correlation

  11. Correlated Condition

  12. Anti-Correlated Condition

  13. 1. Grey Silhouette

  14. 2. Pair of Probes

  15. 3. Test: Which is higher ?

  16. 1 0.8 0.6 0.4 0.2 0 Which is higher ? N=17 percent correct _ + Correlation

  17. Which is brighter ?

  18. 1 0.8 0.6 0.4 0.2 0 Which is brighter ? height N=10 brightness percent correct _ + Correlation

  19. Computational Modeling I(x) =  (x) (Langer and Zucker ‘93)     I(x) = N(x) L d L  (x) (Stewart and Langer ‘96)

  20. + - + - + - Human - Models 1 0.8 0.6 percent correct 0.4 0.2 0 human LZ ‘93 SL ‘96

  21. Conclusion • “Dark-means-deep” cannot account for shape-from-shading perception under diffuse lighting. • Point source models are insufficient. • Our visual system uses a more accurate physical model which is based on the angle of the visible light source.

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