1. INTRODUCTION Graphics 2

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1 1. INTRODUCTION Graphics Level 3 10 credits in Semester 2 Professor Aleš Leonardis Slides by Professor Ela Claridge What is computer graphics? The art of 3D graphics is the art of fooling the brain into thinking that it sees a 3D scene painted on a flat screen. Computer graphics is concerned with the creation and manipulation of graphics images by computer 1

2 Creation (modelling) Manipulation x2 + y 2 + z2 = r2 Manipulation of abstract representations of objects and their parts Implicit Polygonal 3D Modelling x = sin 4θ y = cos 2θ Parametric Individual objects are created and then assembled into final image Volumetric 3-dimensional graphics objects created in an abstract object space Manipulation Manipulation Manipulation of graphics objects Through interactive devices (user) TRINITY Application program (hard-wired) Application program (AI techniques) Animation Individual object geometries are first modelled. These are then linked using positional / orientational relationships (via transforms) 2

3 Graphics images Graphics images: Viewing and Projection Projections of 3-dimensional graphics objects from an abstract object space to a computer screen Similar to taking a photograph locate the object compose a view record the image on a 2D surface (render) camera setup viewport 3d models Graphics images: Camera Positioning Projection - a simulation of a simple pinhole camera Different views of a 3D model 3

4 Graphics images: Projection Graphics images: Rendering Display of images on the screen Advanced rendering techniques surfaces colours shading textures Vermeer Representing three dimensions on two dimensional media Graphics images: Rendering: Surfaces Furnish a 3D wireframe model with a surface Graphics images: Rendering: Colours Light and shadow: colour of different parts of an object suggests its three -dimensional nature 4

5 Graphics images: Rendering: Depth Cues Graphics images: Rendering: Texture mapping Shadows as depth cues Perspective and Depth of Field Highlight/Shadow Graphics images: Rendering: Rasterisation Computer Hardware and software components specifically designed for graphics GPU Interactive devices Displays and hard-copy devices Although the images are flattened to 2D, depth knowledge is required to order them correctly 5

6 3D graphics pipeline Computer graphics Modelling coordinates: - world coordinate system, - object coordinate system WORLD/SCENE/OBJECT/CONCEPT 3D MODELLING VIEWING 3D CLIPPING Creation and manipulation of graphics images by computer Other areas of computing dealing with images image processing computer vision Camera coordinates PROJECTION Screen/Window coordinates RASTERIZATION Device coordinates 2D PIXELMAP DISPLAY 3D Graphics Applications Games Games Entertainment Computer Assisted Drafting (CAD) Medicine Security Commerce Most recognizable 3D application Requires a number of types of skills Graphics Physics Sound Artificial Intelligence (AI) User Interface (UI) 6

7 Entertainment Virtualized human actions Animated movies are a popular form of 3D entertainment Combines movement with 3D graphics Movement can be achieved through motion capture or avars Motion capture actual person or object performs movements with markers tracked by a video camera Avar- Animation Variable - a variable that controls object movement 32 Virtualized human actions Virtual views

8 Computer Assisted Drafting / Design - CAD Medicine Tools used by engineers and designers to assist in design and documentation of new products Nuclear Medicine Viewer Medical applications Medical applications

9 Medical applications Visualisation 3D graphic security tool that can help computer system administrators identify weaknesses in network security Commerce Property Property Business Intelligence E-retail Maintenance, Training, Documentation 3D graphics can be used by a a user to view a specific location in 3D. Note that the tool displayed here permits the user to navigate through a city in 3D but also has a 2D map displayed as a reference. 9

10 Business Intelligence E-Retail Business Intelligence is the collection of data, processed into information that managers can use to make business decisions. Displaying data in 3D helps decision makers gain insight into complex relationships. Modeling environments Virtual(ized) environments

11 Laser scanning Laser scanned models Digital Michelangelo Project Optical triangulation Project a single stripe of laser light Scan it across the surface of the object This is a very precise version of structured light scanning The Digital Michelangelo Project, Levoy et al. Source: S. Seitz Source: S. Seitz Laser scanned models Laser scanned models The Digital Michelangelo Project, Levoy et al. The Digital Michelangelo Project, Levoy et al. Source: S. Seitz Source: S. Seitz 11

12 Laser scanned models Laser scanned models The Digital Michelangelo Project, Levoy et al. The Digital Michelangelo Project, Levoy et al. Source: S. Seitz Source: S. Seitz Maintenance, Training, Documentation 3D Graphics Benefits 3D graphical application applied to a practical application of airplane maintenance, training and documentation Adds realism 3D images can help simplify complexity when displaying graphical relations User can manipulate object views for a full 360 degree perspective Adding a third dimension to data can improve pattern recognition and increase business decision speeds om 12

13 History History First use of computer graphics? 1950 A CRT tube connected to a computer at MIT to investigate aircraft stability and control. early 1950s SAGE air-defence system could display crude radar images. A light pen used for the first time. History Demo: Sketchpad William Fetter coined term computer graphics in 1960 to describe new design methods he was pursuing at Boeing Created a series of widely reproduced images on pen plotter exploring cockpit design, using 3D model of human body. First truly interactive graphics system, Sketchpad, pioneered at MIT by Ivan Sutherland for his 1963 Ph.D. thesis Slide credit: Andries van Dam 13

14 Enabling Modern Computer Graphics Enabling Modern Computer Graphics Hardware revolution Moore s Law: every months, computer power improves by factor of 2 in price / performance as feature size shrinks Significant advances in commodity graphics chips every 6 months vs. several years for general purpose CPUs NVIDIA GTX gigaflops Newest processors are 64-bit, 2, 4, 6, 8, or 10 core Intel Core i7 consumer, up to 6 cores hyperthreaded to provide 12 threads Intel Sandy Bridge EP industrial, 8 cores HT, 16 threads nvidia GeForce TM chip Slide credit: Andries van Dam Graphic subsystems Offloads graphics processing from CPU to chip designed for doing graphics operations quickly nvidia GeForce, ATI Radeon GPUs used for special purpose computation, also bunched together to make supercomputers GPU has led to development of other dedicated subsystems Physics: nvidia PhysX PPU (Physics Processing Unit), standard on many NVIDIA GPUs Artificial Intelligence: IBM Watson Hardware show and tell: Dept s new NVIDIA GeForce GTX 460s 1.35 GHz clock, 1GB memory, 37.8 billion pixels/second fill rate Old cards: GeForce 7300 GT: 350 MHz clock, 256 MB memory, 2.8 billion fill rate Slide credit: Andries van Dam Enabling Modern Computer Graphics Enabling Modern Computer Graphics Input Devices Mouse, tablet & stylus, multi-touch, force feedback, and other game controllers (e.g., Wii), scanner, digital camera (images, computer vision), etc. Whole body as interaction device: Software Improvements Algorithms and data structures Modeling of materials Rendering of natural phenomena Acceleration data structures for ray tracing Parallelization Most operations are embarrassingly parallel: changing value of one pixel is often independent of other pixels Distributed and Cloud computing Send operations into cloud, get back results, don t care how Rendering even available as internet service! Slide credit: Andries van Dam Slide credit: Andries van Dam 14

15 Credits These slides contain material from the following sources: isg.cs.tcd.ie/dingliaj/notes/mm112_7_modelling.ppt mcli.maricopa.edu/files/dvl/3d%20graphics_v2009.ppt 15