Expanded by Jozef Goetz Donald Hearn and M. Pauline Baker Computer Graphics with OpenGL Third Edition. Prentice Hall 2003 ISBN:

Expanded by Jozef Goetz Glossary CG – Computer Graphics Rasterization: The process of determining values for the pixels in a rendered image. Translating an image into pixels. Also called scan conversion. Texture refers to the surface quality (color). Texture mapping is a method of adding realism to a computer-generated graphic. –When a picture is mapped onto an object, the correspondence between the picture's pixels and points on the object's surface is calculated. Specular: reflective, especially light from materials with glossy surfaces

Expanded by Jozef Goetz Glossary Bump mapping: The process of creating and displaying a texture where the values of the texture are used to simulate the bumpiness of an object's surface. –Bump mapping is used to add detail to an image without increasing the number of polygons. –Bump maps do not move the geometry of an object, but they do affect the shading of a surface, giving the illusion of a pattern being embossed on the surface –Bumps are applied by matching up a series of grayscale pixels with colored pixels on the rendered, colored object. Lighter grayscale pixels create a sense of maximum relief or maximum

Expanded by Jozef Goetz Academic Integrity You may discuss general ideas with classmates. You must do each programming assignment entirely by yourself. You may discuss or but not share programs with other students. LV regulations require the professor to report suspected violations of academic integrity.

Expanded by Jozef Goetz Class Web Page Syllabus –Overview of the course. –Schedule of topics and readings. Programming assignments. Guidelines Professor’s lecture notes. Links to resources

Expanded by Jozef Goetz Facilities, Languages, Libraries Facilities: – Computer Lab (Windows XP). –– Your own PC (Windows XP). Languages: – Visual Studio 6.0 with C++ Libraries: – OpenGL: Library developed by Silicon Graphics. – GLUT: Library combining OpenGL with window systems.

Expanded by Jozef Goetz Chapter 1 A Survey of Computer Graphics

Expanded by Jozef Goetz What is Computer Graphics CG? is the field of visual computing, where one utilizes computers both to generate visual images synthetically and to integrate or alter visual and spatial information sampled from the real world computers –Generation of (possibly realistic) images of virtual scenes using computer hardware. In this context it refers to the algorithms, conceptual constructions and mathematical background needed to render virtual scenes either 2D or 3D Really a sub-field of the more general “Virtual Reality” (VR) field, –though VR is usually considered a sub-field of graphics! Distinct from “Image Processing” and CG in which images are scanned into the computer.

Expanded by Jozef Goetz

Computer Graphics = Drawing Pictures with a Computer Rendering is the process of producing the pixels of an image from a higher-level description (object coordinates) of its components. pixels 2D Rendering – Issues: 2D geometry (curves, 2D objects,..), drawing algorithms 3D Rendering – Generating realistic images of non-existent 3D objects/scenes – Issues: geometry (surfaces, 3D objects, …); lighting; view transformations; rendering algorithms;… © 2005 Burkhard Wuensche & Richard Lobb

Expanded by Jozef Goetz Modeling 3D artists make 3D models (“virtual worlds”) –Highly skilled job –Slow work (= expensive!) © by Ken Brilliant, © 2005 Burkhard Wuensche & Richard Lobb

Expanded by Jozef Goetz Computer Graphics used science art engineering business industry medicine government entertainment advertising education training home applications etc.

Expanded by Jozef Goetz Computer Graphics Methods Applied in the design of most products training simulators production of music videos tv commercials motion pictures data analysis scientific studies etc.

Expanded by Jozef Goetz Current trend To produce a realistic view of a natural scene, a graphics program must simulate the effects of –actual reflections and refractions (bending of a ray) from physical objects So the current trend is to incorporate physics principles into graphics algorithms –to better simulate the complex interactions between objects and a lighting environment

Expanded by Jozef Goetz 1-1 Graphs and Charts p.2-3, fig. 1-2 for printed reports slides transparencies animated video used to summarize financial statistical mathematical scientific engineering economic data for –research paper –managerial summaries –consumer info bulletins etc.

Expanded by Jozef Goetz 1-2 Computer-Aided Design CAD for engineering and architectural systems used in the design of –buildings –automobiles –aircraft –watercraft –spacecraft –computers –textiles –home appliances etc.

Expanded by Jozef Goetz 1-2 Computer-Aided Design CAD or Computer-Aided Drafting and Design CADD the shapes used in a design represent the different network or circuit components standard shapes and links between them for mechanical, electrical, electronic, and logic circuit are supplied by the design package –designer can create personalized symbols

Expanded by Jozef Goetz Computer Aided Design (CAD)

Expanded by Jozef Goetz 1-2 Computer-Aided Design CAD Real time, computer animation is used to test a vehicle performance –wire-frame displays (p.7, fig 1-11) allow the designer to see into the interior of the vehicles and to watch the behavior of inner components during motion When object designs are complete, –realistic lighting conditions and surface rendering are applied to produce displays of the final product or ad of the product

Expanded by Jozef Goetz 1-2 Computer-Aided Design CAD p.5-10 If the fabrication of a product can be automated is referred to as CAM Computer- Aided Manufacturing p.8 Architects use interactive computer graphics (CG) methods in CAD packages to lay out rooms, doors, windows, stairs etc. in a building design in a way to optimize space utilization or arrange electrical elements on the circuit board –CAD packages provide facilities for experimenting with 3D interior layouts and lighting

Expanded by Jozef Goetz 1-3 Virtual-Reality Environment p.10 Users can interact with objects in a 3D scene –to examine options by taking a simulated “walk” to find better effect/option of a particular design The new cultural Centre as restoring the old Savona Hospital San Paolo

Expanded by Jozef Goetz 1-3 Virtual-Reality Environment p.10 Computer Graphics are a popular means for evaluating the design of large public complexes, therefore virtual reality is quite a new approach in this area that allows the user to freely navigate and interact By connecting these environments with simulation models, it becomes possible to perform a quantitative analysis of system efficiency. –By evaluating the facilities of a public cultural center or the viability of a town, it is easy to measure the crossing and waiting times and to obtain references for comparing different potential solutions and for optimizing the design

Expanded by Jozef Goetz 1-4 Data Visualizations p are produced as graphical representations for –scientific –engineering –medical etc data sets, referred to as scientific visualization or –commerce –industry –Nonscientific data sets referred to as business visualization

Expanded by Jozef Goetz 1-4 Data Visualizations p used to: scan the large data sets to determine trends and relationships amount data values data sets (a collection of data) can contain scalar values, vectors, higher-order tensors, or any combination of these by converting to a color-coded display (modeling data or color coded visualization) aid in the understanding and analysis of complex processes and mathematical functions fig p.12 simulate of effects (of the 1991 Kuwaiti oil fires fig p.17)

Expanded by Jozef Goetz Scientific Visualization

Expanded by Jozef Goetz Scientific Visualization

Expanded by Jozef Goetz 1-5 Education and Training p used models of physical processes, physiological functions, population trends, or equipment to help trainees to understand the operation of a system. Examples of such specialized system are simulators for –training of ship captain –aircraft pilots –heavy equipment operator –air traffic personnel Most simulators provide screens for visual displays of the external environment

Expanded by Jozef Goetz 1-5 Education and Training p Monitoring flight conditions and Set airplane and environment parameters

Expanded by Jozef Goetz 1-6 Computer Art p used computer-graphics methods and tools for fine and commercial (ex. a logo fig. 1-62, p.27) arts Tools include –commercial software packages (such as Lumena) –symbolic mathematics programs (such as Mathematica) –CAD packages –desktop publishing software –animation software –paintbrush program etc.

Expanded by Jozef Goetz 1-6 Computer Art p Computer-generated animations are used in producing TV commercials. How can we do it? –ad spots are generated frame by frame each frame is rendered (made) and saved as a separate image file –in each successive frame, object positions are displayed slightly to simulate the motions involved in the animation –when all frames in the animation sequence have been rendered, the frames is transferred to film (or stored in a video for playback. Film animations require 24 frames for each sec in the animation sequence (or 30 frames to play back on a video monitor)

Expanded by Jozef Goetz 1-6 Computer Art p

Expanded by Jozef Goetz 1-7 Entertainment p used computer-graphics methods such as computer modeling, computer-rendering and animation for –TV productions –motion pictures –music videos to get special effects, animations, characters, and scenes. For example combine computer-generated figures of people, animals, or cartoon characters with the live actors in a scene p.29, fig or transform an actor’s face into another shape or object p.30 –morphing = one object is transformed (metamorphosed) into another or generate buildings, terrain features, or other background scenes p.29, fig. 1-65

Expanded by Jozef Goetz 1-7 Entertainment p

Expanded by Jozef Goetz Games

Expanded by Jozef Goetz 1-8 Image Processing p used to modify (improve picture quality), analyze and interpret (recognize visual pattern) existing pictures, such as photographs, and TV scans –CG is used to create pictures Typically, a photo/picture is digitized into an image file before image-processing methods are applied

Expanded by Jozef Goetz 1-8 Image Processing p image-processing methods are used to –enhance the quality of the picture p.31 fig –rearrange picture parts –enhance color separations –improve the quality of shading or –retouching Example: medical applications: –tomography is a technique of X-ray photography that allows cross-sectional views of physiological systems –ultrasonics high-frequency sound waves to generate digital data –nuclear medicine scanners collect digital data from radiation that is emitted by ingested radionuclides, and the data is then plotted as color-coded images –computer-aided surgery simulate actual surgical procedure and try out different surgical cuts

Expanded by Jozef Goetz Medical Visualization The Visible Human Project

Expanded by Jozef Goetz 1-9 Graphical User Interface GUI used for applications and operating system software e.g. –Internet Browsers –Innovative Interfaces –Desktop Interfaces a major component is a window manager that allows a user to display multiple rectangular screen areas, called windows GUI includes: –menus selection of options, color values, and graphics parameters –tool bars –icons –popup menus

Expanded by Jozef Goetz 1-9 Graphical User Interface GUI

Expanded by Jozef Goetz Properties of Light We perceive electromagnetic energy having wavelengths in the range nm as visible light. –The perceived color is as much psychological as it is physical.

Expanded by Jozef Goetz The Eye The retina is largely composed of rods and cones. We concentrate on the cones as they determine color perception.

Expanded by Jozef Goetz Color Space

Expanded by Jozef Goetz CIE Color Spaces Norm Color System In 1931 the CIE ( Commission Internationale de l'Eclairage) developed the XYZ color system, also called the "norm color system."CIE This system is often represented as a 2D graphic which more or less corresponds to the shape of a sail. The red components of a color are tallied along the x (horizontal) axis of the coordinate plane and the green components along the y (vertical) axis. In this way every color can be assigned a particular point on the coordinate plane. Colors on the left tend toward gray, which means that their spectral purity is decreased.

Expanded by Jozef Goetz CIE Color Spaces Color spaces can be drawn for different devices (eyes, printer, screen) for comparisons.

Expanded by Jozef Goetz RGB RGB Color cube (what we use in computer graphics) Other color spaces include HSV, YUV, YCrCb, and YIQ Hue, Saturation, Luminance or Hue, Saturation, Value or Hue, Saturation, Brightness) Go to: All Programs->Accessories->Paint->Color->Define Custom Colors

Expanded by Jozef Goetz Graphics Pipelines Graphics processes generally execute sequentially typical ‘pipeline’ model There are two ‘graphics’ pipelines –The Geometry or 3D pipeline –The Imaging or 2D pipeline

Expanded by Jozef Goetz Geometry Pipeline Application – generate geometrical representation from application data Modelling: shapes Shading: reflection and lighting Transformation: viewing Hidden Surface Elimination Imaging Pipeline

Expanded by Jozef Goetz Imaging Pipeline Rasterization and SamplingTexture Mapping Image Composition Intensity and Colour Quantization Geometry Framebuffer/Display Pipeline Rasterization: The process of determining values for the pixels in a rendered image. Translating an image into pixels. Also called scan conversion. Texture refers to the surface quality. When a picture is mapped onto an object, the correspondence between the picture's pixels and points on the object's surface is calculated. Texture mapping is a method of adding realism to a computer-generated graphic.

Expanded by Jozef Goetz An example through the pipeline… The scene we are trying to represent: Images courtesy of Picture Inc.

Expanded by Jozef Goetz Wireframe model – Orthographic views three different views

Expanded by Jozef Goetz Perspective View

Expanded by Jozef Goetz Depth Cue A typical such depth cue is interposition, that is, the occlusion (obstruction) of an object by another...

Expanded by Jozef Goetz Hidden Line Removal – add colour

Expanded by Jozef Goetz Constant Shading – Ambient (surrounding)

Expanded by Jozef Goetz Faceted Shading - Flat i.e. each individual surface is clearly visible

Expanded by Jozef Goetz Gouraud shading, no specular highlights In 3D graphics, a technique developed by Henri Gouraud in the early 1970s that computes a shaded surface based on the color and illumination at the corners of every triangle. Gouraud shading is the simplest rendering method and is computed faster than Phong shading. It does not produce shadows or reflections. The surface normals at the triangle's points are used to create RGB values, which are averaged across the triangle's surface

Expanded by Jozef Goetz Specular highlights added Specular: reflective, especially light from materials with glossy surfaces

Expanded by Jozef Goetz Phong shading Phong shading is a sophisticated smooth shading method, originated by Phong Bui-tuong. Phong shading requires much more computation for the hardware than Gouraud shading. Without it, objects may look faceted, ie each individual surface is clearly visible.

Expanded by Jozef Goetz Texture mapping Texture refers to the surface quality (color). Texture mapping is a method of adding realism to a computer-generated graphic. –When a picture is mapped onto an object, the correspondence between the picture's pixels and points on the object's surface is calculated.

Expanded by Jozef Goetz Texture mapping

Expanded by Jozef Goetz Reflections, shadows & Bump mapping Bump mapping: The process of creating and displaying a texture where the values of the texture are used to simulate the bumpiness of an object's surface. Bump mapping is used to add detail to an image without increasing the number of polygons. Bump maps do not move the geometry of an object, but they do affect the shading of a surface, giving the illusion of a pattern being embossed on the surface.