You are introduced to various pointing devices, such as the mouse, trackball, touchpad, pointing stick, joystick, touchscreen, and pen input. Scanners and reading devices, including optical scanners, optical readers, magnetic ink character recognition readers, and data collection devices are explained,. | Computer Graphics Lecture 24 Fasih ur Rehman Last Class Polygon Clipping Algorithms Today’s Agenda Shading Light, Surface and Imaging Illumination has strong impact on appearance of the surface Surfaces Shading Specular Surfaces Specular surfaces appear shiny because most of the light that is reflected or scattered is in a narrow range of angles close to the angle of reflection. Mirrors are perfectly specular surfaces Diffusive Surfaces Diffuse surfaces are characterized by reflected light being scattered in all directions. Walls painted with matte or flat paint are diffuse reflectors. Perfectly diffuse surfaces scatter light equally in all directions, Flat perfectly diffuse surface appears the same to all viewers. Translucent Surfaces Translucent surfaces allow some light to penetrate the surface and to emerge from another location on the object. This process of refraction characterizes glass and water. Some incident light may also be reflected at the surface. Shadows Shadows created | Computer Graphics Lecture 24 Fasih ur Rehman Last Class Polygon Clipping Algorithms Today’s Agenda Shading Light, Surface and Imaging Illumination has strong impact on appearance of the surface Surfaces Shading Specular Surfaces Specular surfaces appear shiny because most of the light that is reflected or scattered is in a narrow range of angles close to the angle of reflection. Mirrors are perfectly specular surfaces Diffusive Surfaces Diffuse surfaces are characterized by reflected light being scattered in all directions. Walls painted with matte or flat paint are diffuse reflectors. Perfectly diffuse surfaces scatter light equally in all directions, Flat perfectly diffuse surface appears the same to all viewers. Translucent Surfaces Translucent surfaces allow some light to penetrate the surface and to emerge from another location on the object. This process of refraction characterizes glass and water. Some incident light may also be reflected at the surface. Shadows Shadows created by finite-size light source. Umbra – full shadow Penumbra – partial shadow Light Sources Color Sources Ambient Light (uniform lighting) Point Source (emits light equally in all directions) Spot Lights (Restrict light from ideal point source) What Shading can do? Let us suppose we draw a circle Phong Reflection Model A simple model supports three models of light – matter interactions Diffuse Specular Ambient and uses four vectors normal to source to viewer perfect reflector Summary Shading References Fundamentals of Computer Graphics Third Edition by Peter Shirley and Steve Marschner Interactive Computer Graphics, A Top-down Approach with OpenGL (Sixth Edition) by Edward .
