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Graphics 2

06-02408

Level 3 10 credits in Semester 2

Professor Aleš Leonardis

Slides by Professor Ela Claridge

1. INTRODUCTION

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.

What is computer graphics?

  Computer graphics is concerned

  with the creation and manipulation

  of graphics images by computer

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Creation (modelling)

3D Modelling

Parametric

Polygonal

Implicit

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Volumetric

3-dimensional graphics objects created in an abstract “object space”

Manipulation

•  Manipulation of abstract representations of objects and their parts

Individual objects are created and then assembled into final image

TRIN

ITY

Manipulation

Individual object geometries are first modelled. These are then linked using positional / orientational relationships (via transforms)

Manipulation

•  Manipulation of graphics objects –  Through interactive devices (user)

–  Application program (hard-wired)

–  Application program (AI techniques)

•  Animation

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Graphics images

•  “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)

Graphics images: Viewing and Projection

viewport

3d models camera setup

Graphics images: Camera Positioning

Different views of a 3D model

Projection - a simulation of a simple “pinhole” camera

http://photo.net/learn/pinhole/frisius.htm

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Graphics images: Projection

Representing three dimensions on two dimensional media

Vermeer

Graphics images: Rendering

•  Display of images on the screen

•  Advanced rendering techniques –  surfaces –  colours –  shading –  textures

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

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Graphics images: Rendering: Depth Cues

Perspective and Depth of Field

Shadows as depth cues

Highlight/Shadow

Graphics images: Rendering: Texture mapping

http://radoff.com/images/MMOAnatomy3.gif

Graphics images: Rendering: Rasterisation

Although the images are flattened to 2D, depth knowledge is required to order them correctly

Computer

•  Hardware and software components specifically designed for graphics

–  GPU

–  Interactive devices

–  Displays and hard-copy devices

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3D graphics pipeline

WORLD/SCENE/OBJECT/CONCEPT

3D MODELLING

3D CLIPPING

PROJECTION

RASTERIZATION

2D PIXELMAP DISPLAY

Modelling coordinates: - world coordinate system, - object coordinate system

Camera coordinates Screen/Window coordinates Device coordinates

VIEWING

Computer graphics

•  Creation and manipulation of graphics images by computer

•  Other areas of computing dealing with images –  image processing –  computer vision

3D Graphics Applications

•  Games •  Entertainment •  Computer Assisted Drafting (CAD) •  Medicine •  Security •  Commerce

Games

•  Most recognizable 3D application •  Requires a number of types of skills

–  Graphics –  Physics –  Sound –  Artificial Intelligence (AI) –  User Interface (UI)

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Entertainment

•  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

Virtualized human actions

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Virtualized human actions

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Virtual views

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Computer Assisted Drafting / Design - CAD

Tools used by engineers and designers to assist in design and documentation of new products

Medicine

Nuclear Medicine

Viewer

Medical applications

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Medical applications

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Medical applications

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Visualisation

http://blog.tenablesecurity.com/2006/07/3d_tool_screens.html

3D graphic security tool that can help computer system administrators identify weaknesses in network security.

Commerce

•  Property •  Business Intelligence •  E-retail •  Maintenance, Training, Documentation

Property

http://www.geosimcities.com/sol_RealEstate.htm

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.

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Business Intelligence

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.

E-Retail

http://www.virtualshowrooms.co.za http://www.technicon.com/products_demos.html#cf

Modeling environments

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Virtual(ized) environments

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Laser scanning

•  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

Digital Michelangelo Project http://graphics.stanford.edu/projects/mich/

Source: S. Seitz

Laser scanned models

The Digital Michelangelo Project, Levoy et al.

Source: S. Seitz

Laser scanned models

The Digital Michelangelo Project, Levoy et al.

Source: S. Seitz

Laser scanned models

The Digital Michelangelo Project, Levoy et al.

Source: S. Seitz

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Laser scanned models

The Digital Michelangelo Project, Levoy et al.

Source: S. Seitz

Laser scanned models

The Digital Michelangelo Project, Levoy et al.

Source: S. Seitz

Maintenance, Training, Documentation

http://www.parallelgraphics.com

3D graphical application applied to a practical application of airplane maintenance, training and documentation

3D Graphics Benefits

•  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

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History

•  First use of computer graphics?

History

•  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

•  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

Demo: Sketchpad

http://youtu.be/J6UAYZxFwLc

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•  Hardware revolution –  Moore’s Law: every 12-18 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 680… 3090.4 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

Enabling Modern Computer Graphics

nVidia GeForceTM 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

Enabling Modern Computer Graphics

Slide credit: Andries van Dam

•  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: •  http://www.xbox.com/kinect

Enabling Modern Computer Graphics

Slide credit: Andries van Dam

•  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!

Enabling Modern Computer Graphics

Slide credit: Andries van Dam

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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 –  http://hof.povray.org/