1. INTRODUCTION
Graphics 2
06-02408
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
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
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)
3d models
camera setup
viewport
Graphics images: Camera Positioning
Projection - a simulation of a simple
pinhole camera
Different views of a 3D model
http://photo.net/learn/pinhole/frisius.htm
3
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
Graphics images: Rendering: Depth Cues
Graphics images: Rendering: Texture mapping
Shadows as
depth cues
Perspective and
Depth of Field
Highlight/Shadow
http://radoff.com/images/MMOAnatomy3.gif
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
3D graphics pipeline
WORLD/SCENE/OBJECT/CONCEPT
Modelling coordinates:
- world coordinate system,
- object coordinate system
Screen/Window coordinates
Device coordinates
•  Creation and manipulation of graphics images by
computer
3D MODELLING
VIEWING
3D CLIPPING
Camera coordinates
Computer graphics
•  Other areas of computing dealing with images
–  image processing
–  computer vision
PROJECTION
RASTERIZATION
2D PIXELMAP DISPLAY
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)
6
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
33
34
7
Medicine
Computer Assisted Drafting / Design - CAD
Tools used by engineers
and designers to assist in
design and documentation
of new products
Medical applications
Nuclear
Medicine
Viewer
Medical applications
37
38
8
Medical applications
Visualisation
3D graphic security
tool that can help
computer system
administrators
identify weaknesses
in network security.
http://blog.tenablesecurity.com/2006/07/3d_tool_screens.html
39
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.
http://www.geosimcities.com/sol_RealEstate.htm
9
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.
http://www.virtualshowrooms.co.za
Modeling environments
http://www.technicon.com/products_demos.html#cf
Virtual(ized) environments
46
47
10
Laser scanning
Laser scanned models
Digital Michelangelo Project
http://graphics.stanford.edu/projects/mich/
•  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
Laser scanned models
Source: S. Seitz
Laser scanned models
The Digital Michelangelo Project, Levoy et al.
The Digital Michelangelo Project, Levoy et al.
Source: S. Seitz
Source: S. Seitz
11
Laser scanned models
Laser scanned models
The Digital Michelangelo Project, Levoy et al.
The Digital Michelangelo Project, Levoy et al.
Source: S. Seitz
Maintenance, Training, Documentation
3D graphical application
applied to a practical
application of airplane
maintenance, training
and documentation
Source: S. Seitz
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
http://
www.parallelgraphics.c
om
12
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.
http://youtu.be/J6UAYZxFwLc
•  First truly interactive graphics system,
Sketchpad, pioneered at MIT by Ivan
Sutherland for his 1963 Ph.D. thesis
Slide credit: Andries van Dam
13
Enabling Modern Computer Graphics
•  Hardware revolution
Enabling Modern Computer Graphics
•  Graphic subsystems
–  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
nVidia GeForceTM chip
•  Intel Core i7 – consumer, up to 6 cores hyperthreaded to
provide 12 threads
•  Intel Sandy Bridge EP– industrial, 8 cores HT, 16 threads
–  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
•  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
Slide credit: Andries van Dam
Slide credit: Andries van Dam
Enabling Modern Computer Graphics
•  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
14
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/
15