Giáo trình đồ họa - Lesson 1

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Giáo trình đồ họa - Lesson 1

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Tài liệu tham khảo Giáo trình đồ họa - Lesson 1 Kỹ thuật đồ họa và hiện thực ảo

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  1. T ng quan v k thu t ho Lesson 1: K thu t h a và Hi n th c o Computer Graphics And Virtual Reality Các khái ni m t ng quan c a k thu t ho máy tính Các k thu t ho K Thu t h ac s Phân lo i các l nh v c c a k thu t ho h a tiên ti n K Thu t H h at ng tác (interactive) Hi n th c o - VRML Ph n c n g ho (Graphics Hardware) Le Tan Hung (c) SE/FIT/HUT 2002 (c) SE/FIT/HUT 2003 2 A Brief History of Computer A Brief History of Computer Graphics Graphics 1926 – J.L. Baird invents the 1885 - CRT (Cathode Ray Tube) television. 1887 - Edison patents motion picture camera 1888 - Edison and Dickson 30 line vertical, record motion picture photos black and red scan. on a wax cylinder (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 3 4 A Brief History of Computer A Brief History of Computer Graphics Graphics 1963 1966 IBM creates the 360 models Ralph Baer creates the 1st comsumer CG product: One of the First General Odyssey Pinball Purpose Mainframes SRI develops the mouse. (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 5 6
  2. A Brief History of Computer A Brief History of Computer Graphics Graphics 1968 1967 John Whitney: Permutations GE introduces first full colour real time flight In "Permutations," (1968) he simulator for NASA delineates a marvellous and exciting new world. One senses a choreographer. The movements are reminiscent of traditional ballet. The shapes follow the dictates of formal geometry more than those of abstract painting. Movement is three- dimensional and the ambition for a more polished three-dimensional shaded space is apparent. (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 7 8 A Brief History of Computer A Brief History of Computer Graphics Graphics 1973 1974 Michael Crichton’s Intel develop the 8080 processor. “Westworld” uses 2D graphics First time computer is used for image manipulation. 1975 Featured scenes that showed audiences the world viewed by the Mandelbrot plots fractals 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. Bill Gates starts Microsoft (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 9 10 A Brief History of Computer A Brief History of Computer Graphics Graphics 1976 1977 Steve Jobs and Steve Wozniak start Star Wars wins oscar for Apple. special effects. 1977 1978 Academy of Motion Pictures Art and Sciences introduces Visual •Superman wins oscar for Effects category for Oscars. special effects. (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 11 12
  3. A Brief History of Computer A Brief History of Computer Graphics Graphics 1980 1979 Disney’s TRON is the first Alien wins oscar for visual live action film with over effects. 20 mins of computer animations. 1980 Seagate Technology releases the HDD for PCs •The Empire Strikes Back wins oscar for visual effects. (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 13 14 A Brief History of Computer A Brief History of Computer Graphics Graphics 1982 1981 IBM introduces the first IBM PC (16 bit The Genesis Effect (ILM) 8088 chip) for Startrek II is the first all computer animated visual effects shot for • Raiders of the film. Lost Ark wins an oscar for visual effects. (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 15 16 A Brief History of Computer A Brief History of Computer Graphics Graphics 1984 PIXAR Opens 1983 1985 First Coke Polar Bears The Last Starfighter is the Commercial first live action feature film with realistic computer animation of highly detailed models. (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 17 18
  4. A Brief History of Computer A Brief History of Computer Graphics Graphics 1989 1990 The Abyss is the first Windows 3.0 ships movie to include 1993 convincing 3D character animation. Myst 1994 Playstation and N64 released (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 19 20 A Brief History of Computer A Brief History of Computer Graphics Graphics 1995 1996 Quake Released by Independence Day Id Software wins oscar for visual effects. Toy Story becomes the first fully 3D computer animation feature film. (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 21 22 A Brief History of Computer A Brief History of Computer Graphics Graphics 1997 1998 Titanic wins oscar Armageddon for visual effects. Mouse Hunt Bugs Life PIXAR wins oscar 1999 for best short film: Geri’s Game. The Matrix Star Wars: The Phantom Menace Disney’s Tarzan (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 23 24
  5. A Brief History of Computer h a vi tính. K thu t Graphics Definition (ISO) 2000 2002 Microsoft’s XBOX Computer Graphics (K thu t ho máy tính) Sony Playstation II Walking with Dinosaurs Computer graphics deals with all aspects of Disney’s Shrek creating images with a computer model – Interactive Computer Graphics: (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 25 26 K thu t ho i m Pascal / C Bitmap (Sample based-Graphics) program SRGP library Các mô hình, hình nh c a các i t ng c hi n th thông qua t ng pixel (t ng m u r i r c) graphics algorithms positions lines,areas,... colour c i m: Ph ng pháp t o ra các pixel X Window System Graphics hardware Image image formats, compression, transfer (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 27 K thu t ho vector Ví d v hình nh ho Vector Vector = geometrical Graphical Rendering model + rendering Model Parameters Rendering Output Device (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 29 30
  6. Raster and Vector Graphics Raster Hình nh và mô hình c a các v t th c bi u di n b i t p h p các i m c a grid Wireframe Model Skeletal Model Muscle Model Thay i thu c tính c a các pixel => thay i t ng ph n và t ng vùng c a hình nh. Copy c các pixel t m t hình nh này sang hình nh khác. Vector Không thay i thu c tính c a t ng i m tr c ti p X lý v i t ng thành ph n hình h c c s c a nó và th c hi n quá trình tô trát và hi n th l i. Quan sát hình nh và mô hình c a hình nh và s v t nhi u góc khác nhau b ng cách thay i i m nhìn và góc nhìn. © Walt Disney and TSL Hair Render and Touch up Skin (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 31 32 Phân lo i các l nh v c c a Phân lo i theo h to Computer Graphics Kü thuËt ®å ho¹ 2 chiÒu CAD/CAM System KiÕn t¹o ®å Kü thuËt ®å ho¹ ho¹ §å ho¹ minh ho¹ §å ho¹ ho¹t h×nh vμ Kü thuËt ®å ho¹ ba chiÒu Kü thuËt ®å nghÖ thuËt ho¹ Xö lý ¶nh Xö lý ®å Kü thuËt nhËn d¹ng ho¹ Kü thuËt ph©n tÝch vμ t¹o ¶nh (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 33 34 Các ng d ng tiêu bi u c a k thu t ha Phân lo i theo ch c n ng Xây d ng giao di n ng i dùng (User Interface) K thu t x lý nh (COMPUTER IMAGING) T o các bi u trong th ng m i, khoa h c, k thu t K thu t nh n d ng (Computer Vision techniques T ng hoá v n phòng và ch b n i n t attempt to provide meaning to computer) images. Thi t k v i s tr giúp c a máy tính (CAD_CAM) L nh v c gi i trí, ngh thu t và mô ph ng K thu t t ng h p nh (Computer Graphics) i u khi n các quá trình s n xu t (Process Control) Geometry modelling L nh v c b n (Cartography) (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 35 36
  7. (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 37 38 CAD-CAM application H h at ng tác Mô hình h ho t ng tác Các thành ph n c a h ho t ng tác B x lý t ng tác v i ng i s d ng Các chu n c a h ho (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 39 40 Thànhph n trong ch c n ng c a Các thành ph n c a h thà ho t ng tác ho k thu t ho GUI MODELING RENDERING DISPLAYING ( to describe) (to capture) (to show) to the computer the description the image Application Application Graphics what is create 2D image generate Data Program System a table, a car, from 2D / 3D image on Structure models screen Geometric Engine Rendering Engine Raster & Display Engine concerned with: concerned with : concerned with: - modeling - viewing & projection - drawing & clipping - hardware - modeling transf. primitives - how to display Computer - color models - local illumination & Graphics Devices shading (rasterization) - material property - texture mapping - global rendering - lighting property (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 41 42
  8. 3D Graphics Over World Wide Web Model of RGP Animation VRML output pipeline Drawing Pascal / C 3D Graphics WWW packages program output primitives projections transformation output attributes lighting,shading SRGP of objects library Canvascontrol Application Application SRGP model program copyPixel graphics algorithms positions lines,areas,... colour Input device control Display Hardware Input device measures X Window System Graphics hardware input pipeline Image WWW Video (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 43 image formats, compression, transfer B x lý t ng tác v i ng is d ng Thành ph n th vi n ho Các th c th c s H th ng ho thông th ng ph i ch a m t t p h p các th t c i m (pixel) (ch ng trình con) x lý v i các thi t b vào ra (I/O System). ng th ng (line) ng tròn (circle) h th ng ho sinh ra các thi t b ngo i vi lôgic t ng tác a giác (polygon) ..v..v. gi a ng i s d ng và thi t b ngo i vi này. Các thu c tính M t chu trình i n hình c a các ch ng trình ng d ng qu n lý Màu s c (color) Ki u ng v (line style) các thi t b ngo i vi c g i là vòng l p s ki n t thi t b Ki u v n b n (text style) (event-driven loop ) M u tô (pattern). (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 45 46 H th n g ho Giao di n h th ng ha (Graphics System) Interface of Graphics System Interface between application software and graphics hardware system Core, Consists of input subroutines and output subroutines accepting input data or GKS, GKS-3D commands from a user and converting internal representations into external Application program CGI (device interface) pictures on screen, respectively CGM (metafile) Ph n m m ho h th ng: PHIGS (3D and realtime) Graphics system Là t p h p các l nh ho c a h th ng (graphics output commands), X-window Th c hi n công vi c hi n th cái gì (what object) và chúng s c hi n th nh PHIGS+ (PEX) th nào (how). IGES Operating system Ph n m m ho h th ng là ph n m m xây d ng trên c s m t th lo i ph n OpenGL c ng nh t nh và ph thu c vào ph n c ng. DirectX Input and Graphics ho : Ph n c ng Metafiles output devices hardware Là t p h p các thi t b i n t (CPU, b nh màn hình) giúp cho vi c th c hi n các ph n m m ho . (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 47 48
  9. Non-official industry standards Các chu n giao di n c a h ho Các chu n c a h ho GKS (Graphics Kernel System): OPENGL SGI’s OpenGL 1993 GKS Functional Description, ANSI X3.124 - 1985. DIRECTX Direct X/Direct3D 1997 GKS - 3D Functional Description, ISO Doc #8805:1988. CGI (Computer Graphics Interface System): CGM (Computer Graphics Metafile): VRML (Virtual Reality Modeling Language): PHIGS (Programmers Hierarchical Interactive PHIGS Functional Description, ANSI X3.144 - 1985. PHIGS+ Functional Description, 1988, 1992. IGES (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 49 50 OpenGL DirectX Direct control of graphics hardware Software interface to graphics Commands interpreted Direct control of input/output devices, and sound hardware using client-server model Client-server model Client (Application) issues Application program Application program commands 250 distinct commands Server (OpenGL) interprets Object specification + image Direct sound and processes commands Direct X generation Direct input Frame buffer configuration Windows API Direct draw Windows API Simple primitives: points, lines, done by the window system Direct 3D polygons (pixels, images, bitmaps) …….. 3D rendering Windows system Windows system (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 51 52 Ph n c ng ho (Graphics Các thi t b vào ra d li u Hardware) Máy in Các thành ph n ph n c ng c a h ho t ng Dot size: ng kính c a m t i m in bé nh t mà máy tác in có th in c Addressability: kh n ng a ch hoá các i m in có th có trên m t n v dài (dot per inch) S l ng màu có th v trên m t i m Dot size Point per inch InkJet 8 - 20/ 100 inch 200 600 Laser 5/1000 inch 1500 Máy v 6 15/1000 inch 1000 2000 (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 53 54
  10. Màn hình CRT Màn hình CRT Standard Dot-trio SONY Trinitron CRT Hitachi EDP NEC Hybrid Mask (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 55 56 Graphics Devices Các thi t b hi n th d ng vector MOVE 10,15 LINE 400,300 … Interface to … (Display commands) LINE 600,800 MOVE host computer 10 Refesh Buffer (interaction data) 15 Display LINE 100 processor 25 CHAR B DrawLine(A, B): LU CRT CY Turn beam off, LINE move to A. … Stylus Turn beam on, … A move to B. JMP Refresh buffer memory Alphanumeric keyboard Data tablet (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 57 58 Typical raster graphics display showing a house and a star Các thi t b hi n th d ng i m Interface to host computer (Display commands) (interaction data) Keyboard Display processor Data input 00000000000000000000000001000000 00000000000000000000000001000000 00000000000000000000000111110000 00000000011000000001111111111111 CRT 00000000111100000000000111110000 00000011111111000000000001000000 00001111111111110000000001000000 00111111111111111100000000000000 00011111111111111000000000000000 00011111111111111000000000000000 00011111111111111000000000000000 00000000000000000000000000000000 Bitmap refresh buffer (the 1’s are accentuated for contrast) (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 59 60
  11. LCD-Liquid Crystal Display CRT Displays A transmissive technology Advantages Disadvantages Works by letting varying Fast repsonse (high Large and heavy (typ. 70x70 amounts of a fixed-intensity resolution possible) cm, 15 kg) white backlight through an Full color (large modulation High power consumption (typ. active filter depth of E-beam) 140W) Organnic crystals that lign Saturated and natural colors Harmful DC and AC electric themselves together and magnetic fields Inexpensive, matured When external force is applied technology Flickering at 50-80 Hz (no they realign themselves memory effect) Wide angle, high contrast This is used to change and brightness Geometrical errors at edges polarisation and filter light (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 61 62 Future Research Areas H ng nghiên c u LCD Displays Advantages Rendering Disadvantages Graphics accelerators Small footprint (approx 1/6 of CRT) High price (presently 3x CRT) photo-realism parallel processing Light weight (typ. 1/5 of CRT) Poor viewing angle (typ. +/- 50 Geometric modeling real-time Low power consumption (typ. 1/4 of degrees) physically-based CRT) image-based rendering Low contrast and luminance (typ. modeling Completely flat screen - no 1:100) non-photorealistic geometrical errors level of detail Low luminance (typ. 200 cd/m2) Crisp pictures - digital and uniform rendering Motion control / colors synthesis Scientific visualization No electromagnetic emission kinematics / dynamics Geometric algorithms Fully digital signal processing motion capture/ User interface possible modification Large screens (>20 inch) on desktops (c) SE/FIT/HUT 2003 (c) SE/FIT/HUT 2003 63 64



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