1. Upcoming Deadlines Homework #11 – Building a Scene in Maya Due Wednesday, April 28 th (This week) 20 points (10 points if late) Homework #12 – Lighting a Scene in Maya Due Wednesday, May 5 th (Next week) 20 points (10 points if late) There are no more furlough days for this class this semester. For full schedule, visit course website: ArtPhysics123.pbworks.com Pick up a clicker, find the right channel, and enter Student ID

2. Guest Lecture Prof. Raquel Coelho will give a special lecture on lighting in computer generated images. In class, Wed., April 28 th Coelho has worked for studios such as Blue Sky and PDI/Dreamworks, Wildbrain Inc and Tippett Studio, as animator in films such as "Charlotte's Web", "Hellboy", "The Spiderwick Chronicles" and "Happy Feet".

3. Homework #11 For this assignment you will create a simple scene; the assignment that follows will be to light the scene in a variety of ways. In both of these assignments you will be using Autodesk Maya, a popular software application used in animation. You can download a 30-day trial version of Maya from the Autodesk website.

4. Homework #11 The scene that you create in this assignment consists of a floor, a single wall in the background, and some objects in the foreground. Those objects need to be arranged so that they create the shape of the initials of your name. Position the two letters so that they rest on the floor or on each other; do not have them touching the vertical wall.

5. Homework #11 This simple scene was created by Candice Downey.

6. Homework #11 Alternative non-Maya Assignment: If you are unable to use Maya then create a scene like the one described above using real objects (blocks, books, etc.) and photograph the scene. In next week's assignment you will light this scene in a variety of ways so be sure that you can recreate it for that assignment. This assignment is due by 8am on Wednesday, April 28 th 20 points (if late, 10 points)

7. Activating your Clicker * Turn on your clicker. * Enter the channel number or letter for joining this class. Hit Enter/Send key. * Clicker should read AP123S258 * Type in your student ID; hit Enter/Send. Clicker is now ready to use; leave it on. Hit any key to wake the clicker from sleep mode.

8. Survey Question Have you downloaded and installed a copy of AutoDesk Maya? A)Yes and already used it B)Yes but not tried it yet C)No, I’ll use a lab with Maya D)No but plan to do so later E)No, I’ll use photography instead

9. Review Question Electrocution (death by electric shock) is usually due to ohmic heating of the internal organs of the body. True or False

10. Review Question False It is due to the disruption of the nervous system, especially that which controls the heart beat. Electrical system of the human heart

11. Review Question Iron can be magnetized by putting it into a strong magnetic field, for example, in contact with a strong magnet. If the iron remains in contact, the atomic structure aligns itself, turning the iron into a permanent magnet. If iron has been magnetized by aligning it’s atomic structure it is impossible to remove this magnetization. True or False?

12. Review Question False. There are a variety of ways of disrupting the alignment of the iron’s atomic structure, the simplest being to heat the iron.

13. Review Question Wile E. Coyote is surprised when a big metal can of TNT comes flying in, pulled in by his magnet. In reality, the force of the can on the magnet is just as strong as the pull of the magnet is on the can of TNT. True or False ?

14. Review Question True. Another example of action/reaction principle (Newton’s Third Law). Action force is magnet pulling TNT can. Reaction force is TNT can pulling magnet. From “Zipping Along”

15. Effects Animation: Electricity & Magnetism Part 2 (cont.)

16. Demo: Electromagnetic Oscillations Connect to alternating current (AC) Oscillating Magnetic Field Electro- Magnet Put alternating current into an electromagnet and you create an oscillating magnetic field. This oscillating magnetic field induces electrical currents by inducing electrical field oscillations. This is, effectively, a very low frequency electromagnetic antenna. Coil with bulb Put a copper ring in the magnetic field and it gets hot from the induced current (Ohmic heating)

17. EMP (ElectroMagnetic Pulse) A strong, rapidly fluctuating magnetic pulse can induce high voltage, causing strong currents. In 1962, a nuclear test in the Pacific produced an EMP that knocked out 300 streetlights and telephone service in the Hawaiian islands, about 900 miles from the explosion site. Starfish Prime, as seen from Honolulu

18. Call of Duty: Modern Warfare 2 (2009) In the “Second Sun” campaign mission a nuclear missile creates a high-altitude EMP. Streetlights explode, helicopters fall out of the sky, and electronic equipment on weapons is “fried.”

19. Optics & Lighting Part I: Ray Tracing

20. Lighting Lighting is important in all the visual arts, from painting to cinematography. The Orrery, Joseph Wright (1766) Humphrey Bogart in The Maltese Falcon (1941)

21. Up (2009) Let’s look at how lighting in used in a a scene from Pixar’s Up.

22. Key Lighting (One-Point) Simplest type of lighting is with a single dominant light source, called the key. Traditionally, this light source is located on the left side of the scene.

23. Cast Shadows & Form Shadows Form Shadow Cast Shadow

24. Cast Shadows Size and sharpness of a cast shadow depends on: Size of the light source Distance from light to object Distance from light to wall

25. Cast Shadow for Directional Light UMBRA Object Wall A directional light has parallel light rays so the cast shadow is simple to trace on the wall. Dark shadow called the umbra. Shadow is sharp (not fuzzy).

26. Creating Directional Light Light sources, such as bulbs, send light in all directions; directional lighting is created with mirrors or lenses to form the light into a beam. “Barn doors”

27. Cast Shadow for Point Light Source UMBRA Light source (Point) Object Wall Shadow is sharp (not fuzzy). Size of shadow depends on: * Distance from the light to object * Distance from object to wall Light rays spread out from a point light source, such as a bright light bulb or a candle.

28. Film Noir Shadows Shadow Of A Doubt (1943) M (1931) Film noir makes extensive use of cast shadows, manipulating their size for dramatic effect. I Confess (1953)

29. Cast Shadow for Area Lights UMBRA Penumbra Light source Object Wall Rays from a large light source to wall to map out location of deep shadow (umbra) and fuzzy shadow (penumbra). The larger the light source, the smaller the umbra.

30. Umbra and Penumbra An ant on the ground standing in the penumbra could see part of the sun. Standing in the umbra part of the shadow, the ant wouldn’t see the sun at all. No Shadow Penumbra Umbra

31. Solar Shadows UMBRA Penumbra Sun Object The width of the penumbra for a shadow cast by the Sun equals about 1% of the distance from the object to its shadow. Floor Angle = ½ degree ( ) Distance Diagram is not to scale LIGHT Example: If an object is 9 feet (108 inches) from the ground, the penumbra is a little more than 1 inch wide.

32. Penumbra Size Notice how the size of the shadows’ penumbra increases as the shadow gets farther from the base of the tree. Very far from the base the penumbras on each side meet and there’s no more umbra.

33. Light Intensity & Distance The intensity of light decreases as we get farther from the light source. For a point light the intensity decreases quadratically, that is, at twice the distance you have a four times less intensity. The light gets weaker because it is spread over a larger area.

34. Demo: Perspective Cards Hold large card at arm’s length. Close one eye then hold small card at a distance such that it is same size as large card. That distance will be half way between your eye and large card. 1 12 34 Arm’s length Half

35. Area & Distance These four figures are equally spaced in distance and, in perspective, you are standing that distance from the first. At twice the distance, the face is ¼ the size. At four times the distanc e face is 16 th the size.

36. Light Intensity & Angle As angle between the light and a surface increases, the intensity of the light on the surface decreases because it is spread over a larger area. 7 light rays hit surface 5 light rays hit surface

37. Seasons of the Year Northern Hemisphere is warm in July because Earth is tilted towards the Sun. Southern Hemisphere is cold in July since it’s tilted way from the Sun. The seasons are reversed in January. Equator

38. Lighting and Dimension Intensity of light striking a surface varies with angle so the gradient created by a key light is a strong visual cue of an object’s curvature and shape.

39. Form Shadow for Point Light Source Light source (Point) Object The form shadow is completely dark if point source is the only light source (i.e., no ambient or reflected light). Object is brightest where the rays hit head-on and dims going up to the terminator. Terminator

40. Form Shadow for Area Light Source Light source (Area) A B C View from AView from BView from C Terminator widens into a penumbra for an area light.

41. Ambient Light Direct Ambient Most lighting is indirect, coming not from a light source but from reflections off of other surfaces.

42. Fill Lighting Key Fill Key+ Fill With two-point lighting the fill light softens the contrast by adding ambient light.

43. Rim Lighting Key+ Fill Rim Key+ Fill+ Rim Adding a rim light shining from behind distinguishes the foreground objects from the dark background.

44. Three-point Lighting Rim Key+ Fill+ Rim Three-point lighting (Key, Fill, and Rim) is a formula that Hollywood has used for years. From Casablanca (1942) Three-point lighting usually looks good but sometimes too good, that is, it seems fake.

45. Inconsistent Shadows The Birth of the Virgin Fra Carnevale, 1467 The perspective in this painting is pretty good but what’s wrong with the shadows?

46. Inconsistent Shadows The Birth of the Virgin Fra Carnevale, 1467 Long shadows from left to right No shadows? Rising shadows? Downward shadow? Variety of errors yet not immediately noticeable.

47. Next Lecture Guest Lecture: Lighting in CG Animation Homework #11 (Building a Scene in Maya) Due this Wednesday Please turn off and return the clickers!