1. Upcoming Deadlines
Pick up a clicker, find the right channel, and enter Student ID
Homework #12 –Cameras and Lights in Maya Due Tuesday, May 8th (Next week) 20 points (10 points if late) Homework #13 – Creating Stereoscopic 3D Images Due Tuesday, May 15th (Last day of classes) For full schedule, visit course website: ArtPhysics123.pbworks.com

2. Homework #12
For this assignment you are given a photograph of a real object and you will try to match the camera and the lighting.
Each person will have a choice of four photos; for the assignment match any one of these photos (for extra credit, do more than one).
To find the photographs assigned to you, go to:

3. Photo

4. Homework #12 http://tinyurl.com/7zhsaf7
The Maya model for this "widget" object has been created for you and may be downloaded here:
Open the object in Maya, create a surface for it to sit on, position the camera, add some lights, and adjust everything until your rendered Maya image looks as closely as possible to the photograph.
Try to match any colors, for the object and the lights, as well as the details of the shadows (e.g., penumbra angles, ambient light, drop-off).

5. Maya Render

6. Homework #12
To finish, move the position of your camera to view the scene from another direction (suggest that you turn the camera roughly 45 degrees to either side).
Render #1
Render #2

7. Homework #12 Due by 8am on Tuesday, May 8th
Finally, upload the photo you chose to use and the two Maya rendered images into a posting entitled "Recreating Cameras and Lights in Maya."
Note that this is a new assignment this year so there are no examples from previous semesters; contact me if you have any questions.
Due by 8am on Tuesday, May 8th
20 points (10 points if late)

8. Homework #12
Non-Maya Alternative: One of the four photographs is a pair of soup cans. Recreate the camera and lighting in that photograph as accurately as possible then take your own photos of the scene.
Finish by taking a second photograph with the camera at about 45 degrees to either side of its original position.
Upload both of your photographs as well as the photograph that you're matching.
Note that it will not be easy to duplicate the lighting conditions using common house lamps; only do this alternative if you find it absolutely impossible to work with Maya.

9. 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 an example of a final exam from an earlier semester.
You may bring one page of notes double-sided (or two pages single-sided) to the exam.

10. Final Exam
Final exam is on Tuesday, May 22nd from 1215 to 1430 in this classroom.
Visit the course website for more info on your final exam (including sample).
Note that the final exam is optional.
All Assignments and Extra Credit must be turned in by 5pm on May 22nd

11. Survey Question
How would you describe your experience using AutoDesk Maya?
It’s a lot of fun to use
Difficult to use but worth it
Don’t like Maya all that much
It’s a living Hell
Haven’t used Maya

12. Review Question
Lamp
Albert
Where does Albert see the highlight reflected off this metal block? A B C
D: None of these

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

14. 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

15. Lambert Reflection D) Lambert
Lambert surface looks equally bright under different viewing angles.
D) Lambert
Lamp

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

17. 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 the water we see the bottom and little reflection of the sky.

18. Can you cast a shadow on a mirror?
Challenge Question
Can you cast a shadow on a mirror?
Yes No

19. Shadows & Mirrors No No shadow of my arm on the mirror.
Note: If mirror is dirty then shadow is seen on the dust

20. Optics & Lighting Part III: Refraction

21. Elements of Optics Reflection Scattering Eye-Brain Light Source
Refraction

22. 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

23. 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.

24. 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.”

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

26. 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

27. 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.

28. Demo: Invisibility
Pour oil on frosted glass plate; see through the glass

29. Removing scratches
Waxing a surface doesn’t remove scratches, it just matches refraction.

30. 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

31. Refraction in a Wedge Path B
The angle always bends towards the perpendicular going from air to glass. A B C
WEDGE

32. Refraction in a Wedge (2)
Which path does light ray when it reaches the opposite side?
Path A
Path B
Path C A B C
WEDGE

33. Refraction in a Wedge (2)
Path B
Notice that it bends away from the perpendicular going back out of the glass.
By reciprocity the path of the light ray is the same if we reverse the direction of the arrows. A B C
WEDGE

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

35. Demo: Lenses
Light rays converge or diverge by refraction passing through a lens.
Concave lens
Convex lens

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

37. 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.

38. Focusing and Shadows
Water is transparent yet the droplets cast shadows due to refraction.

39. Heat Shimmer and Mirages

40. Mirages
Mirages are caused by the refraction of air because hot air has lower optical density than cold air.
Cool Air
Hot Air

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

42. Image inversion
An object located past the focal point is inverted by a convex lens.

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

44. Hooke’s Micrographia
In 1665, Robert Hooke produced detailed illustrations using the newly discovered instrument: the microscope.

45. The Lens of the Eye
The eye’s lens changes shape to focus the image onto light sensitive cells of retina.
Image is formed upside-down on the retina of the eye.

46. Visual Acuity
If eye’s lens is unable to form image on the retina, an object will appear out of focus.
Myopia
Hyperopic

47. 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."

48. Astigmatism
Astigmatism due to eye’s lens being elliptical, which causes the focus in the vertical to differ from horizontal.
Vertical focus
Astigmatism may be corrected using a cylindrical lens.
In this example, the lens focuses in the horizontal only since vertical is already in focus.

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

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

51. 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

52. 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

53. 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

54. Refraction in Aquariums
Seeing around the side of log
Mirror reflection of sculpture

55. Refraction in Aquariums
Different views on front and side walls due to refraction
Total internal reflection off side wall

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

57. Demo: Laser in Water Stream
Total internal reflection causes light to reflect inside a stream of water.
Laser

58. Next Lecture Scattering
Homework #12 Recreating Cameras and Lights in Maya
Due Tuesday, May 8th (Next week)
Please turn off and return the clickers!