Upcoming Deadlines Homework #11 Building a Scene in Maya Due Tuesday, May 1 st (Next week) 20 points (10 points if late) Homework #12 Cameras and Lights in Maya Due Tuesday, May 8 th (In two weeks) 20 points (10 points if late) For full schedule, visit course website: ArtPhysics123.pbworks.com Pick up a clicker, find the right channel, and enter Student ID Character Animation Winners Wicked Breakdance by Graeme PottsGreat balanced poses and good timing! Jason Spencer-Galsworthy Character Animation Winners Stop Motion Walk By Aaron Soon The Bad Day By Adrianne Thater Homework #11 For this assignment you will create a simple scene using Autodesk Maya, a popular software application used in animation. You can download a 30-day trial version of Maya from the Autodesk website. You will also use Maya in Homework #12 where you will try to recreate the camera and lighting for a simple composition. 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. Homework #11 This scene was created by Tom McKee. Homework #11 Post your rendered image on blog in an entry entitled Building a Scene in Maya. Due by 8am on Tuesday, May 1 st 20 points (if late, 10 points) Extra Credit (10 points): Create images of your scene lit using one-point, two-point, and three-point lighting. Homework #11 Extra Credit One-point Lighting Three-point Lighting Two-point Lighting Homework #11 Extra Credit Some tips on how to light your scene, if you do the extra credit. One-point Lighting: Light the scene with a single bright spot light on the left side; this is your key light. Scene by Candace Downing Created by Candace Downey 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. Homework #11 Extra Credit Survey Question How would you describe your experience using AutoDesk Maya? A)Its a lot of fun to use B)Difficult to use but worth it C)Dont like Maya all that much D)Its a living Hell E)Havent used Maya Review Question The fuzzy edge of a cast shadow is called the __________. A)Umbra B)Penumbra C)Form shadow D)Umber E)Castaway Review Question B) Penumbra Notice how the cast shadow of Ellies arm is sharp while the shadows of the leaves of the tree on their faces are fuzzy. The farther the object is from the light, the wider the penumbra. Sharp Fuzzy Review Question In three point lighting, the third light shining from behind to distinguish the foreground objects from the dark background. This is called the _______. Three Point Lighting A)Key Light B)Fill Light C)Rim Light D)High Light E) Low Light Review Question Rim C) Rim Light From Casablanca (1942) The rim light is sometimes called the back light or the kicker. Because its often used to accent a persons hair its also called the hair light or the shoulder light. Review Question The intensity of light shining on a surface from a point light or an area light depends: A)Only on the distance between the light source and the surface. B)Only on the angle between the light source and the surface. C)On both the distance and the angle. D)On neither the distance nor the angle. Review Question 7 light rays hit surface 5 light rays hit surface C) On both the distance and the angle. In both cases the light rays are spread over a larger area when the distance or the angle increases. Distance Angle Optics & Lighting Part II: Reflection Reflection and Shaders What makes wood look like wood and metal look like metal? Its not just the color of a surface that indicates the material but also how it reflects light. In computer graphics, how light reflects from a surface is determined by the shader assigned to that surface. Specular and Diffuse Reflection Reflection from most surfaces is diffuse, with incoming light scattered in all directions. Reflection from mirror surfaces is specular, with light reflecting in one direction. Mirror Diffuse reflection Specular reflection Law of Specular Reflection Angle of incidence equals angle of reflection SPECULAR REFLECTION Demo: Blackboard Optics Special blackboard has mounted light source and mirrors. Light Source Mirror Demonstrates the Law of Reflection Incident Reflected Demo: Who Do You See? A B C D E MIRROR Which person in the front row sees the guy with the hat in the mirror? A B C D E Demo: Who Do You See? Diffuse light MIRROR Person A sees the guy with the hat when looking in the mirror. The converse is also true: Person E sees Person A in the mirror. Reciprocity Laser Path of light rays is always reversible. This symmetry for light rays is called reciprocity. Mirror Viewer Water Laser Mirror Viewer Water Finding the Highlight A B C D: None of these Lamp Where does Albert see the highlight reflected off this metal block? Albert Finding the Highlight Lamp Albert C Light rays from point C reach Albert. Sunrise/Sunset on the Ocean Instead of a single highlight we see a long street of light on the ocean at sunset. We are seeing many highlights from many random points on the wavy surface where the angle is just right to reach us. Direction of the Street of Light The direction of the street of light on the ocean is always perpendicular to the horizon. Harbour with Villa Medici, Claude Gelle (1637), Uffizi Gallery The direction of the street of light in this painting is incorrect. Parallax Person A Person B B A Top View Ray tracing helps in determining parallax angles, which depend on the distance between objects and the viewer. Boat Diffuse Surface is Not a Mirror Light rays diffusely scatter in every direction from every spot on the surface. See a light ray from the top of your head reflected from this spot. Also see light ray from the tip of your nose reflected from this spot. Look at this spot on a diffuse surface Lambert Diffuse Reflection The apparent brightness of a Lambert surface is the same regardless of the observer's angle of view. This is typical of matte surfaces, such as paper and cloth. In computer graphics, Lambertian reflection is often used as a model for diffuse reflection. Rotating the view or scaling the object doesnt change the apparent brightness of its surface. Key + Fill Key only Lamp Diffuse Reflection and Viewer Angle Looks equally bright under different viewing angles. Directional Light on Diffuse Surface All points of a Lambert diffuse surface look equally bright under directional light. No Highlight for Diffuse Surface Lamp No highlight on a Lambert diffuse surface but a gradual gradient due to angle with the lamp. This end is brighter because its closer to the lamp and because surface faces head-on. Form shadow Phong Reflection Phong reflection is a surface model combining the diffuse reflection of rough surfaces with the specular reflection of shiny surfaces. Shiny surfaces have small intense specular highlights, while dull surfaces have large highlights that fall off gradually. Other Maya Shaders Blinn - Surfaces highlights are similar to Phong but with soft-tinted highlights as on metallic surfaces. Phong E - A faster rendering version of Phong that yields somewhat softer highlights. Anisotropic Stretches highlights and rotates them based on the viewer's position; ideal for materials such as hair, feathers, brushed metal, and satin. Shading Map - Creates a "cel" look to mimic traditional, hand-drawn animation. Layered - Combine several shaders to create a more complex material. Raytracing & Flat Mirrors Tracing light rays from original, to mirror, to eye allows us to construct image. Original Mirror Raytracing & Flat Mirrors Tracing light rays from original, to mirror, to eye allows us to construct image. Original Mirror Raytracing & Flat Mirrors Tracing light rays from original, to mirror, to eye allows us to construct image. Original Mirror HAIR NOSE TIE Image Demo: Pocket Mirror See full image of your head in a plane mirror thats half the size of your head. Original Image Demo: Pocket Mirror See full image of your head in a plane mirror thats half the size of your head. Mirror Mirror Reflections in Perspective Mirror reflection of this bird is almost an upside-down duplicate. In general, the reflection is not such a duplicate due to visual perspective. Image in the Mirror Edouard Manet, A Bar at the Folies-Bergere, 1882 Alfred Stevens, La Parisienne japonaise, c.1873 Gerard ter Borch, Woman at a Mirror, c.1650 Which work of art has a correct reflection? Incorrect Correct Image in the Mirror Utamaro, Woman Powdering Her Neck Velazquez, Venus at her Mirror Helmut Newton, Bergstrom over Paris Which work of art has a correct reflection? Incorrect Correct Transparent, Reflecting Surfaces Water and glass are transparent but reflect some of the light striking their surface. Can see inside the cab through the right window. Strong reflection of the sun on the left window. Can see some of the riverbed through the water surface. Reflection Coefficient Air Water 100% 2% Air Glass 100% 4% Air Silver 100% 90% Water Glass 100% % These values are for direct incidence (zero degrees). Reflection tends to increase at larger angles of incidence. Water Air 100% 2% Note: Reflection coefficient does not depend on which side the light comes from. Looking in Windows Bright Sky & Dark Interior: Reflection is brighter than Transmission Bright Interior & Dark Street: Transmission brighter than Reflection Looking in Windows Bright Sky & Dark Interior: Reflection is brighter than Transmission Bright Interior & Dark Street: Transmission brighter than Reflection Glass Dark Interior Glass Bright Interior One Way Mirror One way mirror can be just a clear glass window. Bright Room Dark Room Discussion Room (Bright) Observation Room (Dark) GLASS Reflected light from bright room masks transmitted light from the darkened observation room Ken Lums One Way Mirror Art piece based on one way mirror. Fresnel Effect The dependence of reflection on angle is called the Fresnel effect. Looking straight down into a pool of water we see little reflection of the sky. Looking at the water at a large angle we see a strong reflection of the sky. Reflection Coefficient The percentage of light that reflects from the surface of a transparent material is the reflection coefficient. Small angle Large angle Weak Reflection Strong Reflection Reflection coefficient depends on the material but also on the angle that the light hits the surface. Fresnel Effect for Water Reflection coefficient of water rises quickly for large angles of incidence. 50% 100% Small angle Weak Reflection Large angle Strong Reflection Fresnel Effect on Water Small angle Weak Reflection Large angle Strong Reflection Fresnel Effect on Glass Fresnel in Paintings Clyde Aspevig Question to think about Can you cast a shadow on a mirror? Note: If you try this at home, make sure that your mirror is clean. Next Lecture Lighting Part III Scattering & Refraction Homework #11 (Building a Scene in Maya) Due next Tuesday Please turn off and return the clickers!