CSC480: Computer Graphics Dr. Yaser Khamayseh Assistant Professor Computer Science Dept Jordan University of Science and Technology . Topics to Cover • Introduction to Computer Graphics: definition, history, applications, hardware, and software • A guide to OpenGL • Algorithms for drawing 2D primitives: lines, circles, ellipses, filling, clipping, generating characters • Geometrical 2D and 3D transformation • Viewing in 3D: viewing 3D objects on 2D computer monitor • Color and lighting • Advanced topics `Ìi`ÊÜÌ ÊÌ iÊ`iÊÛiÀÃÊvÊ vÝÊ*ÀÊ* Ê `ÌÀÊ /ÊÀiÛiÊÌ ÃÊÌVi]ÊÛÃÌ\Ê ÜÜÜ°Vi°VÉÕV° Ì Introduction What is Computer Graphics? Applications History Display Technologies Graphics Library What is Computer Graphics? • Computer Graphics is concerned with producing images using a computer – Modeling: Create and represent the geometry of objects in the 3D world – Rendering: Generate 2D images of the objects – Animation: Describe how objects move Modeling • Take the real and turn it into a virtual • Explain the real world or fantastic objects using mathematics • If the image does not exist in real life, a blueprint is drawn by an artist A wire frame is the simplest form of model Wireframe Model Rendering • Draw the image on 2D screen • Color • Lighting Wireframe Model • Shading • Surface texture • Shadows • Reflection and transparency • Intersection, surface- Final Render removal hiding Animation • Control the movements of objects • Laws of physics • Biomechanics, • Special effects In Comparison to Image Processing • Image Processing: analysis of scenes, or the reconstruction of 2D or 3D objects from their images – Image enhancement: Eliminate noise or enhance contrast in an image – Pattern recognition: Detect and classify patterns in an image – Computer vision: Recognize and reconstruct a 3D model of a scene from several images Computer Graphics and Image Processing • The main task in computer graphics is to create pictures and images to synthesize them on the basis of some description, or model, in a computer. • The main task in image processing, on the other hand, is – to improve or alter images that were created elsewhere, perhaps digitized from photographs or captured by a video recorder. – Processing can remove "specks" of noise from an image, enhance the contrast of the image, sharpen its edges, and fix its colors. – Software routines can be used to search for certain features in an image and highlight them to make them more noticeable or understandable. Output Image Description Image Processing Image Pattern Image Recognition, Computer Vision Input Description Computer Other Data Processing Graphics Image Enhancement Example Graphics Applications: User Interfaces Graphics Applications: Cinema, Games Pixar: Monster’s Inc. Graphics Applications: Medical Visualization MIT: Image-Guided Surgery Project The Visible Human Project Graphics Applications: Computer- Added Design ` Graphics Applications: Virtual Reality Elumens’ VisionStation CMU CUBE History (1/14) • The term “Computer Graphics” was coined in 1960 by William Fetter to describe new design method he was pursuing at Boeing – Widely reproduced images were created on a plotter exploring cockpit design using a 3D model of a human body “Perhaps the best way to define computer graphics is to find out what it is not. It is not a machine. It is not a computer, nor a group of computer programs. It is not the know-how of a graphic designer, a programmer, a writer, a motion picture specialist, or a reproduction specialist. Computer graphics is all these – a consciously managed and documented technology directed toward communicating information accurately and descriptively.” Computer Graphics , by William A. Fetter, 1966 ´ History (2/14) 1885: Cathod Ray Tube History (3/14) Whirlwind Computer (MIT, 1950): input via keypunch, output via printer/plotter, both in batch Cool facts : Whirlwind, built in the early 50’s at MIT, cost $4.5 million and could perform 40,000 additions/second. Mac 512K, list price $3,195 in 1984, could do 500,000. Today, commodity PCs perform approximately one billion operations/second Sketchpad (Sutherland, MIT, 1963): first truly interactive graphics system, using a CRT monitor, light pen, and function-key pad first CAD system (IBM, 1959) ^ History (5/14) 1966: Ralph Baer creates the 1st consumer CG product: Odyssey Pinball History (6/14) 1967 • GE introduces first full color real time flight simulator for NASA History (7/14) 1973: Michael Crichton’s “Westworld” uses 2D graphics • First time computer is used for image manipulation. • Featured scenes that showed audiences the world viewed by the eye circuitry of a synthetic human (played by a very real Yul Brenner) in a future Western theme park. This effect was achieved with 2D computer graphics tools mostly derived from image processing techniques. History (8/14) 1974: Intel developed the 8080 processor. 1975: Bill Gates started Microsoft 1976: Steve Jobs and Steve Wozniak started Apple. History (9/14) 1977: Academy of Motion Pictures Art and Sciences introduced VISUAL EFFECT category for Oscars. Winner: Star Wars History (10/14) 1981 • IBM introduces the first IBM PC (16 bit 8088 chip) History (11/14) 1983: First Coke Polar Bears Commercial History (12/14) 1985: The Last Starfighter is the first live action feature film with realistic computer animation of highly detailed models. 1989: The Abyss is the first movie to include convincing 3D character animation. History (13/14) 1990: Windows 3.0 ships 1994: PlayStation and N64 released 2000: PlayStation 2 2002: MS XBox History (14/14) 2002 • Academy of Motion Pictures introduced a category for BEST ANIMATED FEATURE. • Winner: Shrek Uses of Computer Graphics We can conclude that the uses of Computer Graphics in general are Display of Information, Design, Simulation (scientific visualization, entertainment, education/training), User Interface (Windows OS, Mac, X, Next etc.). Computer Graphics is used in specific areas : Business/Office automation (Desktop publishing., E-mail., Hypermedia. ), Graphs (Business., Math., Modeling.), Image Processing (Satellite, Medical., Weather, Police.), CAD/CAM (Industry, Electrical Circuit Design, Landscape, Buildings, Materials.), Art and Design (Graphic Design., Presentation, Television, Advertising.), Animation (Games, Virtual Reality, Cartoons, Nuclear/Chemical Reactions.), Cartography (Geology, Oceanography , GIS etc.) Scientific Analysis and Visualization. Output Technologies Raster Display Vector Display 1963 1972 1980’s timeline Xerox PARC Vector Display (1/2) Vector Display (2/4) • Refresh buffer stores the computer-produced display list or display program; it contains: – point- and line-plotting commands – character-plotting commands • The beam from CRT is deflected from endpoint to endpoint. Vector Displys (3/4) video displays called "vector," "random-scan," or "calligraphic" displays that produce line drawings. These devices specially designed to sweep an electronic beam from point to point across the face of a cathode-ray tube, leaving a glowing trail. Since each line segment to be displayed ( two endpoints and perhaps a color), vector displays can draw a vector picture very rapidly (hundreds of thousands of vectors per second). ` Disadvantages of Vector Displays: • Vector displays, cannot show smoothly-shaded regions or scanned images. Region filling is usually simulated by cross-hatching with different line patterns, • Today raster displays have largely replaced vector displays, except in very specialized applications. Raster Display (1/20) 2 - Raster Displays The most familiar raster displays are the video monitor connected to personal computers and workstations, and the flat-panel display common to portable personal computers. Other common displays produce hard copy of an image: the laser printer, dot matrix printer, ink-jet plotter, and film recorder. ´ Raster Display (2/20) • Raster is a matrix of pixels representing the entire screen area. At each pixel, the beam’s intensity reflects the pixel’s intensity • The screen is scanned sequentially from left to right, top to bottom. Scan line Horizontal Vertical retrace retrace Vector vs. Raster ^ Pros. and Cons. of Raster • Advantage: – Lower cost CRT technologies – The ability to display areas filled with solid colors or patterns, which is essential for realistic images of 3D objects • Disadvantage: – Aliasing: the image is not smooth – Computationally demanding for drawing primitives, thus not good for wireframes Raster Image • Pixels : A "pixel" (picture element) is a relative unit and has no absolute size. If you divide a picture into any number of square samples of any size, you could call these samples as pixels. It doesn't matter what size, only that they are all the same size. A raster image is stored in a computer as an array of numerical values. The array is thought of as being rectangular, with a certain number of rows and a certain num•ber of columns. Each numerical value represents the value of the pixel stored there. The array as a whole is often called a "pixel map." The term "bitmap" is also used • Raster images also frequently contain images of straight lines. A line is created in an image by setting the proper pixels to the line's color. • But quite a bit of computation may be required to determine the sequence of pixels that "best fit" the ideal line between two given endpoints. Pixel depth: • Two bits per pixel produce 4 gray levels • four bits per pixel produce 16 gray levels • eight bits per pixel produce 256 gray levels Raster Displays All raster