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

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

10. Geons (Biederman '87)

11. Cavanagh's model

12. two-tone images

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

17. 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 Cavanagh's claim

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

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

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

23. shadows and lighting

26. transparen cy

27. humans don't do ray tracing

30. line drawings are universal

31. recognition with few cues

32. 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 take-home lessons?

33. Marr's model (circa 1980) Cavanagh's model (circa 1990) Two models of Human visual processing stimulu s 2D shape memor y 3D shape 2½D sketch Objec t 3D model feedback basic recognition with 2D primitives reconstruction of shape from image features object recognition by matching 3D models primal sketch