WELCOME TO COMPUTER GRAPHICS ☺ LECTURE 1: INTRODUCTION TO COMPUTER GRAPHICS

Dr. Abdallah Namoun

abdallah.namoun@gmail.com

Computer Graphics - CPCS 391

Plan

� Learning Outcomes

� Course outlines / Syllabus

� Assessment

� Introduction

� Applications of Computer Graphics

Learning Outcomes

� Understand the key concepts and applications of computer graphics.

� Apply mathematics, physics and computer programming to achieve computer graphics.

� Understand the techniques used in displaying two or three dimensional graphics.

� Be familiar with the graphics algorithms.

� Be familiar with the computer graphics software applications.

� Be familiar with the computer graphics hardware.

� Implement and resolve graphics problems using OpenGL.

Practically

� Problem solving skills: think about programmable problems and come up with solutions

� Design skills: create workable design solutions

� Programming skills: enhance C / C++ programming skills

� Creativity: graphics require creativity

Course Outline

1. Introduction to Computer Graphics

2. Computer Graphics Hardware

3. Geometry and Introduction to OpenGL

4. Displaying Two and Three Dimensional Graphics using OpenGL

5. Algorithms for Displaying Graphics

6. Geometric Transformations

7. Viewing in 3D

8. Color and Transparency

9. Texture

10. Illumination and Shading

11. Basics of Computer Animation

Things this course is not about !

� Paint and Imaging packages

� Adobe photoshop and similar products

� Microsoft Paint … etc

� CAD packages (AutoCAD)

� Modeling packages (3D Studio Max)

� Animation packages (Digimation)

Prerequisites for this Course

� Software Engineering Skills � Object-oriented design

� Programming / debugging / testing

� C++ (or knowledge of Java)

� Linear Algebra � Vectors and matrix arithmetic, dot and cross

products � E.g. Helps to understand Transformations

� I will focus more on CG concepts rather than maths

How Will the Course Evolve?

� Will start with the basics

� Then move to 2D graphics � 2D modelling

� Simple image transformations

� Then move to 3D graphics � Curves and surfaces

� Geometry

� Transformations: (translation, rotation, scaling, etc)

� Camera models

� Scene graph traversal

How Will the Course Evolve?

� 3D Modelling and Rendering

� Intersection of rays with solid objects

� Lights and Shadows

� Textures

� Color theory

� User Interfaces

� Animation

Course Documents

� Course plan will be put online as a guide (e.g. E-portal)

� Lecture slides and assignments will be put online on a weekly basis

� Lecture topics, assignment deadlines, and mid-term tests are subject to change

� Programming code of assignments has to be submitted to myself via email: � abdallah.namoun@gmail.com

� Your Teaching Assistant: Mr. Fahid El-Anizi

Please send me a blank email

� I need your email address to keep you updated

� abdallah.namoun@gmail.com

� Subject line: CPCS391

Administrative Stuff / Logistics

� Announcements

� Will be made during class &

� Will be posted online

� Questions � Office hours

� Monday (10-11am) and

� Wednesday (10-11am)

� Outside office hours: email me to arrange a private consultation

� Attendance: mandatory

� If you can not make it, please let me know why!

Course Timetable

Session Day Time Room

Theory Sunday 10:00 – 10:50am 305

Tuesday 10:00 – 10:50am 305

Practical Monday 1 – 3pm 206

Wednesday 1 – 3pm 204

Text Books

� Recommended but not required �

� OpenGL Manual:

https://www.opengl.org/sdk/

� Supplementary references

� John F. Hughes, Andries van Dam, Morgan McGuire, David F. Sklar, James D. Foley, Steven K. Feiner, Kurt Akeley, “Computer Graphics: Principles and Practice”, 3rd edition, Addison-Wesley, 2013

ISBN-10: 0321399528, ISBN-13: 978-0321399526

� Edward Angel; Dave Shreiner,“Interactive Computer Graphics: A Top-Down Approach with Shader-Based OpenGL”, 6th edition, Addison-Wesley, 2011

ISBN-10: 0132545233, ISBN-13: 978-0132545235

Assessment and Grading Policy

Coursework 50%

• Classwork / Exercises 10%

• Programming Assignments 30%

• Mid-Semester Test 10%

Final Examination 50%

Programming Assignments

� Four Main Programming Assignments

� To start on week 3

� Labs are on a weekly basis

� Once out, solutions must be submitted a week later � Example: if assignment is announced on week 3,

solution programs are due on week 4

� Assignments may change as the course progresses to accommodate needs and skills

� Advice: Always start EARLY

Programming Assignments

� Collaboration policy

� Only applicable to programing assignments

� High level design of programs (Allowed)

� To enhance understanding

� Detailed discussion of programs (Not allowed)

� Copying of code: Not allowed

� This may be different to other courses in the department

Late Submission Policy

� Submission on deadline day, but after submission hour: 5% penalty

� Your mark – 5%

� Submission after deadline day:

� For each day after the submission day, a 10% penalty is applied

� Your mark – (days late * 10%)

Part Two

What Is Computer Graphics?

� Simple terms: the technology for presenting information in the form of pictures (i.e. how it looks like)

� Creation, manipulation, and storage of geometric objects (modelling), and their images (rendering) � Modelling: how can we represent objects?

� Rendering: How can we view and display objects?

� Display those images on � Screens

� Hardcopy devices

� Image processing

Key Steps of Image Generation

1. Modelling

3. Viewing 2. Rendering

Image Generation

Modelling

� Modelling is concerned with specifying and representing real environments in terms of: � Geometry: curves, surfaces, volumes

� And how to build these representations

� Generate primitives from points such as � Lines, � Triangles, � Quads, � Patches � Cylinder, � Sphere

Modelling using Polygons

� Polygons are 2 dimensional shapes, defined by a set of closed straight lines. � Polygons = “many angles”

� The segments of the polygon are called edges or sides

� The points where two edges meet are called vertices (single: vertex)

� Polygons have at least 3 sides (i.e. 3 sides or more)

� Polygons can be colored, shaded and textured

� Position of Polygons in space is defined by coordinates of vertices

Examples of Polygons

Example of Complex Modelling

Rendering

� What is an image? � Distribution of light energy on 2D film

� Rendering refers to generation of images from a 3D scene � Input: 3D description of scene + camera � Project 3D objects onto projection plane � Output: create image from camera’s viewpoint (clipping and

orientation)

� Rendering involves adding: light, texture, and color

� How do we represent and store images? � Sampled array of pixels: p[x, y]

Rendering

Basics of Images

� There are two types of graphics / images:

1) Raster (Pixel) Graphics: images are created using pixels in a grid

� Pixels are dots; they are samples of color in an image

� Poor quality when stretched (thus Not Scalable)

� Common format: BMP, GIF, JPEG, PNG, TIFF, PSD (Photoshop)

2) Vector Graphics: images are created using vectors, i.e. scalable objects defined by math equations

� No loss of quality when stretched (thus Scalable)

� Common format: AI (Adobe Illustrator), CDR (CoreIDRAW), SVG

Raster: Single pixels (dots) are used to create

objects

Vector: Primitives created using mathematical formulas which produce very smooth

lines and curves

What type is this image? Raster or Vector?

What Are the Applications of Computer Graphics?

� Many areas including � Video Games � Simulation � CAD – CAM Design � Architecture � Special Effects - Movies � Virtual Reality � Visualisation � Medical Imaging / Visualisation � Education � Geographic Information Systems

Scientific: Data Visualisation

� Charts and Graphs

� For example: in Microsoft Excel

� Bar charts, Pie charts, line graphs

� Used to summarise financial, mathematical data etc

Scientific: Data Visualisation

� CG makes vast amount of data accessible and readable

� New data representations to facilitate interpretation of data visually

� Creation of models from acquired data

Entertainment: Game Industry

� Have to think about the scenes

� Illumination / lights

� Coloring

� Movement through the scenes

� Collision of objects

Entertainment: Animation and Movies

� Animate objects

� Visual Effects (liquids, gases, destruction, fracture, explosions, imaginary creatures, motion capture,)

� If you can imagine it, it can be done with computer graphics

Educational: Medical Imaging

� Tools for teaching / education

� Models of physical objects

(.e. human organs)

� Tools for diagnosis

Drug Design

Virtual Reality / Simulation

� Immersive interfaces / environments

� You would need to wear a device (e.g. head mounted)

� Can also have educational / training purposes

� Understanding of complex systems

� E.g. flight simulation

� Military training

Computer Aided Design (CAD)

� Mechanical, electronic and architectural designs

� Better conceptualisation, better interaction

� Transfer of ideas

� Reduced design cycles

Image Processing and Graphical User Interfaces

� Start with a picture

� Process picture information, i.e. manipulate 2D images by applying operations to pixel grid

� Processing involves:

� Color correction

� Scaling

� Blurring

� Sharpening

Image Synthesis

� Image synthesis (also known as image generation)

� Construction of images from scratch, rather than processing of existing images

� Synthesis of a 2D image from a 3D scene description

�� also known as rendering

� Two types or rendering

� Photoreal rendering

� Non-photoreal rendering

Photoreal Rendering

� Photoreal Rendering refers to rendering of a 3D scene in a realistic way.

� This requires the generation of a correct image using a given input data set

� The photoreal rendering algorithms are based on:

� Ray tracing algorithm: traces the path of individual light rays starting from the eye and working backwards to the light sources

Non-Photoreal Rendering

� Non-Photoreal Rendering refers to rendering images in other ways (non-realistic)

� It is done to achieve

� Aesthetic goals such as artificial water colors

� Maximise the communication of visual information, e.g. medical visualisation

Computer Vision

� A separate discipline from Computer Graphics

� However, it shares many things in common with Computer Vision

� It aims to

� Take a set of 2D images (e.g. from videos) and infer a 3D description of what is being viewed

� Understand the contents of the images

� This is different from rendering

� It relies on Artificial Intelligence

OpenGL

� OpenGL is an interactive rendering specification designed for ease of use and portability across a wide range of systems

� OpenGL is an API that enables us to send commands to the graphics card to draw:

� 2D scenes

� 3D scenes

OpenGL

How to Draw using OpenGL

� We inform OpenGL

� The geometry of the object to be drawn

� Vertex positions / coordinates

� Vertex normals

� 3 Vertices make a triangle

� Camera parameters � Field of view

� Aspect ratio

� More information � Color

� Transparency

� Texture … etc

OpenGL Example

…

glBegin(GL_TRIANGLES);

glColor3f(1.0, 0.0, 0.0); // red

glVertex3f(-6.0, -3.0, 0.0);

glColor3f(0.0, 1.0, 0.0); // green

glVertex3f(5.0, -3.0, 0.0);

glColor3f(0.0, 0.0, 1.0); // blue

glVertex3f(0.0, 4.0, 0.0);

glEnd();

…

OpenGL Pseudo Code Sample main() {

// Initialization code:

// - Open window

// - Load & define texture maps, etc.

while(not finished) {

// Frame set up code:

// - Clear screen

// - Specify camera position & properties

// - Specify lighting information

for(each object) {

// Object set up code

// - Specify object position & orientation (matr ix)

for(each material) {

// Specify material properties

// - Lighting properties

// - Texture properties

for(each primitive) {

// Render primitive (glBegin, glVertex3f…)

}

}

}

// Frame completion code (glSwapbuffers()…)

} // Shutdown code

}

Glossary – Key Terms

� Computer Graphics: ت ا����وب� ر�و

� 2D (dimensions): د ا�� 2

� 3D (dimensions): 3 د� أ�

� Modelling: م��� � Rendering: د�م�� � Geometry: ا���د����م

� Concept: وم�� � Application: ط��ق� � Transformations: ت� ��و

Summary

� Course outline / topics

� Assessment policy

� Definition of Computer Graphics

� Presentation of Key Concepts in Computer Graphics

� Applications of Computer Graphics

� Next week: Computer Graphics Hardware