Computer Graphics  
Lecture 01 Introduction  
Edirlei Soares de Lima  
What is Computer Graphics?  
The term computer graphics describes  
any use of computers to create and  
manipulate images [Marschner, S., et  
al., 2015].  
Computer graphics is the science and  
art of communicating visually via a  
computer’s display and its interaction  
devices [Hughes, J. F., et al., 2013].  
What is Computer Graphics?  
Computer graphics is a cross-disciplinary field:  
Physics (e.g.: model light behavior);  
Mathematics (e.g.: describe shapes);  
Human Perception (e.g.: only render things that will be  
Human-Computer Interaction (e.g.: interaction devices);  
Engineering (e.g.: optimize allocation of memory, and  
processor time);  
Graphic Design and Art (e.g.: make the computer-to-  
human communication more effective);  
What is Computer Graphics?  
Geometric Modeling  
Rendering and  
Computer Vision  
Image Processing  
Computer Graphics Areas  
Modeling: Deals with the mathematical specification of shape  
and appearance.  
Definition of surface, interpolation rules, reflection models.  
Computer Graphics Areas  
Rendering: Term inherited from art create shaded images  
from 3D computer models.  
Many techniques and styles of rendering.  
Computer Graphics Areas  
Animation: technique to create an illusion of motion through  
sequences of images.  
Time is a key issue, not usually dealt with in basic modeling and  
Computer Graphics Areas  
Image processing: deals with the manipulation of 2D images  
and is used in both the fields of graphics and vision.  
Computer Graphics Areas  
Virtual reality: attempts to immerse the user into a 3D virtual  
Typically requires at least stereo graphics and response to head  
Computer Graphics Areas  
3D scanning: uses range-finding technology to create  
measured 3D models.  
Computer Graphics Areas  
Computational photography: explores the use of computer  
graphics, computer vision, and image processing methods to  
enable new ways of photographically capturing objects,  
scenes, and environments.  
Applications Video Games  
Video games increasingly use sophisticated 3D models and  
rendering algorithms.  
Applications Cartoons  
Cartoons are often rendered directly from 3D models.  
Many traditional 2D cartoons use backgrounds rendered from 3D  
Applications Visual Effects  
Visual effects use almost all types of computer graphics  
Superimpose backgrounds with separately filmed foregrounds.  
Synthetic environments, objects, and even characters.  
Applications Animated Films  
Animated films use many of the same techniques that are  
used for visual effects, but without necessarily aiming for  
images that look real.  
Applications CAD/CAM  
Computer-Aided Design and Computer-Aided Manufacturing  
use computer technology to design parts and products on the  
computer to guide the manufacturing process.  
Applications Simulation  
Simulation can be thought of as accurate video gaming.  
Applications Medical Imaging  
Medical imaging creates meaningful images of scanned  
patient data.  
Applications Information Visualization  
Information visualization creates images of data that do not  
necessarily have a “natural” visual representation.  
Graphics Hardware  
Computer hardware and software (graphics card and device  
driver) that generates computer graphics and allows them to  
be shown on a display.  
The processors on GPUs are highly parallel and support  
thousands of concurrent threads.  
The hardware is designed to process larger numbers of pixels and  
vertices in short amounts of time.  
Graphics APIs  
A graphics API (Application Program Interface) is a set of  
functions that perform basic operations such as drawing  
images and 3D surfaces into windows on the screen.  
Graphics APIs vs User-Interface APIs.  
Dominant Graphics APIs: Direct3D and OpenGL.  
Graphics Pipeline  
The Graphics Pipeline is a special software/hardware  
subsystem that efficiently draws 3D primitives on screen.  
Is optimized for processing 3D triangles with shared vertices.  
The basic operations in the pipeline map the 3D vertex  
locations to 2D screen positions and shade the triangles so  
that they both look realistic and appear in proper back-to-  
front order.  
Geometric manipulation using matrices and vectors.  
The speed at which images can be generated depends  
strongly on the number of triangles being drawn.  
Raster Images  
Most computer graphics images are  
presented to the user on some kind of raster  
Raster displays show images as rectangular arrays  
of pixels.  
Different colors are achieved by mixing varying  
intensities of red, green, and blue light.  
A raster image is simply a 2D array that stores  
the pixel value for each pixelusually a color  
stored as three numbers, for red, green, and  
blue (RGB model).  
Graphics Coding  
Class Design: vector2, vector3, vector4, matrix4x4, transform, ...  
Float vs. Double: tradeoff between performance and precision.  
Optimizations are important, but unnecessary "optimizations"  
make the code harder to read without speeding things up.  
Debugging Graphics Programs:  
Images as coded debugging output;  
Traditional debugger;  
Data visualization for debugging;  
Further Reading  
Hughes, J. F., et al. (2013). Computer Graphics: Principles and Practice  
3rd ed.). Upper Saddle River, NJ: Addison-Wesley Professional. ISBN: 978-  
Chapter 1: Introduction  
Marschner, S., et al. (2015). Fundamentals of Computer Graphics (4th  
ed.). A K Peters/CRC Press. ISBN: 978-1482229394.  
Chapter 1: Introduction  
Chapter 3: Raster Images