01/20/04© University of Wisconsin CS 559: Computer Graphics Prof Stephen Chenney Spring

01/20/04© University of Wisconsin Today Course overview and information Getting started on images

01/20/04© 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, …

01/20/04© University of Wisconsin Is 2D Graphics Important? Compositing in movies: images are created in layers, and then combined Sprites in games: Images are built by overlaying characters and objects on a background

01/20/04© University of Wisconsin Virtual Reality Iowa Driving Simulator Augmented Reality W. Eric L.Grimson at MIT vision/surgery/surgical_navigation.html 3D is Sometimes Essential

01/20/04© 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.

01/20/04© University of Wisconsin This Course: Building Blocks Images and computers –Sampling, Color, Filters, … Drawing in 2D –Drawing lines and triangles, 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, …

01/20/04© University of Wisconsin People Prof. Stephen Chenney –Room 6387 –Office Hours: TBD TA: Matt Anderson –Office Hour TBD TA: Eric McDaniel –Office hours TBD Send all class to It is read by both Prof Chenney and the TAs and gets the fastest response

01/20/04© University of Wisconsin Web and The class web site is –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 –I assume that you check this 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 –If you don’t have a CS class account, go to the CSL on the 2 nd floor of the CS building

01/20/04© University of Wisconsin Textbooks and Reader Peter Shirley, “Fundamentals of Computer Graphics”, A.K. Peters, 2002 Woo et. al., "OpenGL Programming Guide", Third or Fourth Edition, Adison-Wesley, 1999 or 2003 –The definitive guide to OpenGL, and a reasonable description of general real-time 3D graphics –It doesn’t really matter which edition – the differences are not pertinent to this class Class reader: Available at DOIT sometime real soon now –A collection of papers, textbook chapters, and other documents –Some essential material not contained in the textbook

01/20/04© 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

01/20/04© 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

01/20/04© University of Wisconsin Grading (approximate) 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

01/20/04© University of Wisconsin Lab Facilities Room B240 contains machines for use in this class They have reasonably 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 that someone else scrawled up But they also sometimes have incorrect information!!

01/20/04© 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: OpenGL will be the 3D rendering toolkit –Provides an API for drawing objects specified in 3D –Included as part of Windows and in most Linux distributions Although getting hardware acceleration may take some doing Visual Studio.NET (Visual C++ 7.1) will be the programming environment for grading To be graded, your projects must compile under Visual C++ on the machines in room B240

01/20/04© 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: – –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 –Visual Studio also throws up some hiccups – we will provide a transition tutorial

01/20/04© University of Wisconsin Adding the Class To go on the waiting list, with your name, ID and Do it again even if you have already send me People who add in this manner will have to wait a couple of days for accounts

01/20/04© University of Wisconsin Images Information presented in a flat (2D) format to be examined visually We are familiar with many forms of image: –Photographs –Paintings –Sketches –Television –Computer screens Each form has its own way of obtaining and storing the information content

01/20/04© University of Wisconsin Digital Images Many formats (100s) exist for storing images on a computer –JPEG, GIF and PNG to name just a few There are some conflicting goals: –The storage cost should be minimized –The amount of information stored should be maximized The size of something and the amount of information is contains are not the same thing –Tracking ownership may be important Most formats you are familiar with are raster images

01/20/04© University of Wisconsin Raster Images A raster is a regular grid of pixels (picture elements) Raster image formats store the color at each pixel, and maybe some other information –Easiest is to use a simple array of pixel values –Some formats store the pixel information in very different ways –Eg a 5x3, floating point, grayscale image

01/20/04© University of Wisconsin Vector Images Vector formats offer an alternative way to store images The most common use of vector formats are in fonts – images of characters (Postscript, TrueType) Store images as collections of geometric primitives –E.g. Lines, polygons, circles, curves, … It is possible to go from a vector image to a raster image –We’ll learn how It is very hard to go the other way

01/20/04© University of Wisconsin Trade-Offs Which format, raster or vector, is easier to: –Resize (scale bigger or smaller)? –Rotate? –Crop (cut bits off at the edges)?

01/20/04© University of Wisconsin Obtaining Digital Images What are some methods for obtaining a digital image?

01/20/04© 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 Who cares? –We will go into this in some detail 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?

01/20/04© University of Wisconsin Key Concepts #1 Raster images store a regular grid of pixel colors Vector images store primitives that combine to form the image Display and storage are not the same thing

01/20/04© University of Wisconsin Next Time We focus on raster images Some human perception stuff (always fun)