CS 559: Computer Graphics
Prof Stephen Chenney
Fall 2002
http://www.cs.wisc.edu/~cs559-1
09/03/02
© 2002 University of Wisconsin
Today
• Course overview and information
• Getting started on images
• Programming assignment 1 (off class home page)
09/03/02
© 2002 University of Wisconsin
What is Computer Graphics?
• Technically, it’s about the production, manipulation and
display of images using computers
• Practically, it’s about movies, games, art, training,
advertising, communication, design, …
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© 2002 University of Wisconsin
Is 2D Graphics Important?
Compositing in movies: images are
created in layers, and then combined
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Sprites in games: Images are
built by overlaying characters
and objects on a background
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3D is Sometimes Essential
Virtual Reality
Augmented Reality
Iowa Driving Simulator
http://www.nads-sc.uiowa.edu/
W. Eric L.Grimson at MIT
09/03/02
http://www.ai.mit.edu/projects/medicalvision/surgery/surgical_navigation.html
© 2002 University of Wisconsin
Computer Graphics?
The Wooden Mirror, by Daniel Rozin
It consists of many small wooden blocks with a
camera in the center. The camera takes an image,
it is converted to intensities, and each block is
rotated to reflect an appropriate amount of light.
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© 2002 University of Wisconsin
This Course: Building Blocks
• Images and computers
– Sampling, Color, Filters, …
• Drawing in 2D
– Drawing lines and polygons, clipping, transformations
• Drawing in 3D
– Viewing, transformations, lighting, the standard pipeline
• Modeling in 3D
– Describing volumes and surfaces, drawing them effectively
• Miscellaneous interesting stuff
– Raytracing, animation, …
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© 2002 University of Wisconsin
People
• Prof. Stephen Chenney
– Room 6387
– Office Hours Tues 2-3,
Thurs 11-12
– schenney@cs.wisc.edu
• TA: Matt Allen
– Office Hour TBD
– matthew@cs.wisc.edu
• TA: David Gekiere
– Office hours TBD
– gekiere@cs.wisc.edu
Send all class email to cs559-1@cs
It is read by both Prof Chenney and the TAs and gets the
fastest response
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© 2002 University of Wisconsin
Web and Email
• The class web site is http://www.cs.wisc.edu/~cs559-1
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It is updated very frequently
Lecture notes are put online before class, and updated after class
Additional resources and links are provided
Reading for future classes is listed
• The class mailing list is cs559-1list@cs.wisc.edu
– I assume that you check this email regularly
– All notices are sent out on the mailing list, including things not
mentioned in class
– The mail goes to your cs class account, so make sure you check
that or set up forwarding
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© 2002 University of Wisconsin
Textbooks and Reader
• Peter Shirley, “Fundamentals of Computer Graphics”, A.K.
Peters, 2002
• Woo et. al., "OpenGL Programming Guide", Third Edition,
Adison-Wesley, 1999
– The definitive guide to OpenGL, and a reasonable description of
general real-time 3D graphics
• Class reader: Available at DOIT
– A collection of papers, textbook chapters, and other documents
– Some essential material not contained in the textbook
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© 2002 University of Wisconsin
Projects
• There will be three projects for the course, spread evenly
through the semester
• Project 1: Image editing
• Project 2: Running a maze
• Project 3: Building a virtual theme park
• You must submit all three in order to pass the course
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© 2002 University of Wisconsin
Homeworks
• There will be a homework every two weeks or so
• They are intended primarily to explore topics further and to
prepare you for the exams
• They will be graded, but only the best five will count
• Some essential techniques will be presented only in
homework
– For example, an review of linear algebra
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© 2002 University of Wisconsin
Grading (approximate)
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45% Midterm and Final
45% Projects
10% Homework
Everyone must write up their own homework
For the projects, you have the option of working in pairs
09/03/02
© 2002 University of Wisconsin
Lab Facilities
• Room B240 contains machines for use in this class
• They have high performance hardware and the software to
make it work
• Students in CS 559 have priority in the lab, but it shouldn’t
be a problem
• Don’t underestimate the benefits of working in a lab with
your classmates
– For instance, the blackboards frequently display useful hints
• But they also sometimes have incorrect information!!
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© 2002 University of Wisconsin
Software Infrastructure
• FLTK will be the user interface toolkit
– Provides windows, buttons, menus, etc
– C++ class library, completely portable
– We are currently at version 1.1.0rc6, available for free: www.fltk.org
• OpenGL will be the 3D rendering toolkit
– Provides an API for drawing objects specified in 3D
– Included as part of Windows, available for Linux either as Mesa (software)
or hardware drivers
• Visual C++ 6.0 will be the programming environment for grading
• To be graded, your projects must compile under Visual C++ on the
machines in room B240
09/03/02
© 2002 University of Wisconsin
C++
• This is probably the first, and only, class in which you must complete
large software projects in C++ without step by step instructions
• There is a great deal of freedom in the projects, which requires that you
do your own software design
• If you are not comfortable in C++, you will have to take action
• There are tutorials intended to teach you C++ assuming you know Java:
– http://www.cs.wisc.edu/~hasti/cs368/CppTutorial/index.html
– These are intended for the course CS 368, but just do the tutorials
• The transition to C++ was one of the biggest issues for past CS559
students
09/03/02
© 2002 University of Wisconsin
Adding the Class
• To go on the waiting list, email schenney@cs.wisc.edu with
your name, ID and major
• Do it again even if you have already send me email
• People who add in this manner will have to wait a couple of
days for accounts
09/03/02
© 2002 University of Wisconsin
Programming Assignment 1
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Do the Visual C++ and FLTK demo off the class web page
Will get you started with C++ and FLTK
Do it NOW, don’t wait until the project comes up
There will be another assignment in a week or so continuing
your preparation for the first project
• Not graded. Questions during office hours or on the class
mailing list
09/03/02
© 2002 University of Wisconsin
Images
• Information presented in a flat (2D) format to be examined
visually
• We are familiar with many forms of image:
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Photographs
Paintings
Sketches
Television
Computer screens
• Each form has its own way of obtaining and storing the
information content
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© 2002 University of Wisconsin
Digital Images
• Images can be stored on a computer in one of many forms
• There are some conflicting goals:
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The storage cost should be minimized
The amount of information stored should be maximized
It should be easy to perform editing operations
Tracking copyrights may be important
• There are two abstract types of digital images: Raster
images and Vector images
09/03/02
© 2002 University of Wisconsin
Raster Images
• A raster is a regular grid of pixels (picture elements)
• Raster image formats store the intensity (brightness) and
color information at each pixel
– Simplest is to use a 2D array of pixel values
– Some formats store the pixel information in very different ways
• A 6x3 image
• Aspect ratio is width/height, 2
09/03/02
© 2002 University of Wisconsin
Vector Images
• Store images as collections of geometric primitives
– E.g. Lines, polygons, circles, …
• Called vector images for historical reasons
• Postscript (PDF) is the most famous vector image format
• It is possible to go from a
vector image to a raster image
• It is very hard to go the other
way
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© 2002 University of Wisconsin
Obtaining Digital Images
• What are some methods for obtaining a digital image?
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© 2002 University of Wisconsin
Obtaining Digital Images
• What are some methods for obtaining a digital image?
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Digital camera
Scanning another image
Medical scanning
Editing existing digital images
Paint or drawing programs
Created from abstract data (e.g. math function plot)
Rendered from a scene description
…
© 2002 University of Wisconsin
Displaying Images
• Display is not the same as storage
– A monitor displays an image, but does not store it
– The same image may look different on different monitors
• Typically, the display is taken into account when creating
images, but not always
• Different display techniques have very different properties
• What are some common display techniques?
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© 2002 University of Wisconsin
Displaying Images
• What are some common display techniques?
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Cathode Ray Tube (CRT): Computer monitor / Television
Liquid Crystal Display (LCDs)
Printing: many variations
Vector displays
Holographic displays
Plasma displays
…
© 2002 University of Wisconsin
Trade-Offs
• Which is preferred: Raster or Vector?
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For display on an LCD?
For display on a plotter (a printer that draws lines with pens)?
For images from digital cameras?
For CAD (Computer Aided Design)?
For high-quality text?
• Which is easier to:
– Resize?
– Rotate?
– Crop?
09/03/02
© 2002 University of Wisconsin
Trade-Offs
• Which is preferred: Raster or Vector?
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For display on an LCD? Raster
For display on a plotter (a printer that draws lines with pens)? Vector
For images from digital cameras? Raster
For CAD (Computer Aided Design)? Vector
For high-quality text? Vector
• Which is easier to:
– Resize? Vector
– Rotate? Vector
– Crop? Raster
09/03/02
© 2002 University of Wisconsin
Next Time
• We focus on raster images
• Some human perception stuff (always fun)
09/03/02
© 2002 University of Wisconsin