Upcoming Deadlines

1. Pick up a clicker, find the right channel, and enter Student ID Upcoming Deadlines Homework #12 – Lighting a Scene in Maya Due Thursday, December 1st (This week) 20 points (10 points if late) Homework #13 – Creating Stereoscopic 3D Images Due Thursday, December 8th (Next week) 20 points (10 points if late) For full schedule, visit course website: ArtPhysics123.pbworks.com

2. Homework #12 Light the scene created in your previous homework assignment using one, two, and three-point lighting. One-point Lighting: Light the scene with a single bright spot light on the left side; this is your key light. Created by Candace Downey

3. Homework #12 Two-point Lighting: Add a dim fill light on the right side to soften the shadows created by the key light. Three-point Lighting: Add a bright rim light behind the letters to accentuate their edges from the dark background. Created by Candace Downey

4. Homework #12 Render the three scenes, save each image, and upload them to your blog. Due by 8am on Thurs., December 1st 20 points (if late, 10) All Assignments and Extra Credit must be turned in by 5pm on Thursday, December 8th (last day of classes) Created by Candace Downey

5. Final Exam Final Exam will have of 10 short essay questions on material covered in lecture. Final exam counts for 50 points. See course website for copy of last semester’s final exam. You may bring one page of notes double-sided (or two pages single-sided) to the exam.

6. Survey Question How much time did last week’s homework (Building a Scene in Maya) take you to complete? • Less than an hour • Between one and two hours • Between 2 and 4 hours • Over four hours • Didn’t finish that assignment

7. Finding the Highlight Lamp Albert Where does Albert see the highlight reflected off this metal block? A C B D: None of these

8. Finding the Highlight Lamp Albert C Light rays from point C reach Albert.

9. Review Question • Matte surfaces, such as paper and cloth, are typically rendered in computer graphics using which shading model? • Phong • Blinn • Thong • Lambert • Mambo Key only Key + Fill

10. Review Question D) Lambert Johann Heinrich Lambert (1728–1777) A Lambert surface scatters light diffusely so under directional light it looks equally bright from all angles.

11. Review Question What is the shape of the mirrors in these photos? A) Concave Mirror B) Convex Mirror

12. Review Question A) Concave Mirror Original Mirror Image

13. Review Question The dependence of reflection on angle is called the ______ effect. Looking at the water at a large angle we see a strong reflection of the sky. Looking straight down into a pool of water we see little reflection of the sky.

14. Review Question The dependence of reflection on angle is called the ______ effect. • Reflex B) Reflux C) Rephase • D) Fresnel E) What-The-Flux Large angle Small angle Strong Reflection Weak Reflection

15. Fresnel Effect The dependence of reflection on angle is called the Fresnel effect. Looking at the water at a large angle we see a strong reflection of the sky. Looking straight down into a pool of water we see little reflection of the sky.

16. Optics & LightingPart III: Bending & Scattering

17. Global Illumination Advanced computer graphics uses global illumination algorithms to compute a more physically realistic rendering of a scene. Without GI With GI Notice focusing of light through glass sphere

18. Refraction Light rays bend (refract) passing from water to air, making objects appear to be shallower and closer to the observer. Observer sees image Image Image Actual Actual

19. Reciprocity Light bends the same way whether it’s entering the water or coming out of the water. Laser This symmetry for light rays is called “reciprocity.”

20. Law of Refraction Light passing from one material to another is refracted by an angle that depends on the optical density of each material. Angle is smaller in the denser material.

21. Demo: Refraction thru a Block Light is refracted entering the block and refracted back on leaving the block.

22. Optical Density Optical density is given by the index of refraction, n. The larger the difference between the indices at an interface, the larger the angle of refraction for light rays crossing the interface. Air n = 1.0 n = 1.3 Water Air n = 1.0 n = 1.5 Glass Air n = 1.0 n = 2.4 Diamond

23. Demo: Invisibility Mineral oil and glass have nearly the same index of refraction A glass rod is nearly invisible in a beaker of mineral oil. A diamond, however, is easily seen.

24. Refraction in a Wedge Which path does light ray take after entering the glass wedge? • Path A • Path B • Path C A B C WEDGE

25. Refraction in a Wedge Path B The angle always bends towards the perpendicular going from air to glass. Notice that it bends away from the perpendicular going back out of the glass. A B C WEDGE

26. Lenses Curvature of a lens surface produces a continuous, variable angular refraction. Concave lens shrinks its image Convex lens magnifies its image

27. Demo: Concave Lenses Curved surface of a concave lens causes light rays to diverge, dispersing the light and shrinking any images.

28. Demo: Convex Lenses Curved surface of a convex lens causes light rays to converge, focusing the light and possibly magnifying images.

29. Camera Lens Using a lens allows for light to be focused on a screen or camera film. No image (Diffuse) Camera with lens

30. Demo: Real Image of Convex Lens Image formed by convex lens can be observed on a screen.

31. Bokeh Effect (Lens Blur) Point lights expand into balls of light when the light source is out of focus (outside the depth of field). The term is from the Japanese word boke (暈け or ボケ), which means "blur" or "haze."

32. Focusing and Shadows When refraction focuses light to create bright areas, it also removes light and creates shadowed areas. Dark Bright

33. Caustics Refraction caustics Caustics are the bright concentrations of light caused by the focusing of that light by refraction or by reflection. Reflection caustics Caustics also create shadow patterns, which visually accent the caustic’s brightness.

34. Total Internal Reflection When refraction angle exceeds 90º the light does not cross the surface. Refracted Reflected Reflected

35. Demo: Total Internal Reflection Past the critical angle all the light is internally reflected. Just below critical angle

36. Demo: Total Internal Reflection Prism demonstrates total internal reflection if the angle of incidence is large enough. No light escapes to this side No light escapes to this side No light escapes to this side

37. Looking up Underwater Try this when you’re in the pool or the ocean next summer. Looking straight up you see the sky but outside the 96° cone surface is like a mirror

38. Natural Lighting Underwater Due to total internal refraction sunlight never enters the water at more than about a 45 degree angle. Image seen underwater Sun

39. Fiber Optics Total internal reflection causes light to reflect inside a solid glass tube.

40. Separating Colors Blue wavelength of light refracts slightly more than the red, creating rainbows. Water Droplet Glass Prism

41. Rainbows Rainbows are formed by refraction from many, many raindrops. The red part is always above the blue part.

42. Double Rainbow Primary Secondary

43. Atmospheric Perspective Objects in the distance have a bluish, unsaturated color due to atmospheric scattering of blue light (same as blue sky).

44. Atmospheric Perspective Example

45. Mt. Hadley

46. View From EVA 3

47. Dave Scott on the Slopes of Mt. Hadley Delta Pan

48. Mt. Hadley (14,000 ft) Apollo 15 Landing Site 20 km Photographer Mt. Hadley Delta (11,000 ft)

49. Mauna Loa (~height as Mt. Hadley) from ~20 km away