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cavanagh's pseudorealism

cavanagh's pseudorealism. Jan 23 - David Thompson. (Outline). 1. Marr's Model 2. Cavanagh's Model 3. What more can artists tell us about vision? . the Marr vision model. the Marr vision model. input image. the Marr vision model. primal sketch. the Marr vision model. 2.5-D sketch.

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cavanagh's pseudorealism

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  1. cavanagh's pseudorealism Jan 23 - David Thompson

  2. (Outline) 1. Marr's Model 2. Cavanagh's Model 3. What more can artists tell us about vision?

  3. the Marr vision model

  4. the Marr vision model input image

  5. the Marr vision model primal sketch

  6. the Marr vision model 2.5-D sketch

  7. the Marr vision model 3D model

  8. the Marr vision model Object object-centric coordinates 3D model 2½D sketch viewer-centric coordinates primal sketch stimulus

  9. the Marr vision model recognition with object-centric 3D models Object object-centric coordinates 3D model 2½D sketch viewer-centric coordinates primal sketch bottom-up reconstruction of shape from image features stimulus

  10. Geons (Biederman '87)

  11. Cavanagh's model

  12. two-tone images

  13. “attached shadow” contour hair (not shadow!) “cast shadow” contour inferred external contours

  14. Cavanagh's claim A. Finding 3D structure in two-tone images requires distinguishing cast shadows, attached shadows, and areas of low reflectivity B. The images do not contain this information a priori D. Therefore, our recognition process must involve matching viewpoint-specific 2D templates

  15. What else can art tell us about object recognition? Cavanagh's model

  16. What else can art tell us about object recognition? Cavanagh's model neurobiological evidence! (Logothetis '95)

  17. What else can art tell us about object recognition? Cavanagh's model memory basic recognition with 2D primitives 3D shape 2D shape top-down feedback stimulus

  18. shadows and lighting

  19. transparency

  20. humans don't do ray tracing

  21. line drawings are universal

  22. recognition with few cues

  23. take-home lessons? Human object recognition uses shortcuts, not complete physical models - local lighting - simplified reflections At least some of our processing happens through “simple vision” - viewer-centric 2D template matching - simple 3D memory provides top-down feedback

  24. Two models of Human visual processing Marr's model (circa 1980) Cavanagh's model (circa 1990) object recognition by matching 3D models Object basic recognition with 2D primitives memory 3D model 3D shape 2½D sketch 2D shape feedback primal sketch reconstruction of shape from image features stimulus stimulus

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