CSC 315-LECTURE1

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CSC 315: COMPUTERGRAPHICS

(4CU)By: Mr. Dan Dandas Abudu AbwangDepartment of Computer Science,Faculty of Science-Gulu University

Tel: +256-773-027702, +256-703-606601Email: [email protected]

[email protected]



SAMPLING, MORPING ANDRENDERING



Course Objectives

To provide general knowledgeto the theory and practice of

computer graphics To show that the consistentdesign of user interfaces based

on existing standards areimportant



You should know...Basic linear algebra, Vectors, matrices,

simple coordinate systemsBasic calculus

Limits, derivatives, integrals, notation

C/C++; Either is ok, but we provide moreutility code for C++

Please write standards-compliant code

Your code should compile with a C89/C++98 compiler

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How to Pass thiscourse...

Attend the lectures. Yes, attendance ismandatory. You can not skip lecturesunless have special conditions

(communicated to the dept).Understand the concepts

Do the assignments

Try to get the bonus credits especially inprojects

Do the exams

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How to Fail thiscourse...Skip the lectures Ignore the concepts and onlymemorize formulae

Slack on the assignments Miss the exams

Violate the Your Honor Code



AssessmentsExams (60%); In class (End of Semester-around Nov-December, 2010)

Programming Assignments (20%);

Tests(20%); Two Compulsory testsProjects both individual or group isencouraged and presented on monthlybasis



TopicsIntroduction, Sampling, Morphing, Rendering

Ray Casting, Illumination, Model Transformation

Scan Conversion and Shading, Visibility

Sub-division Surfaces, Parametric curves &

surfacesAnimation Dynamics and Kinematics

Image Based Modeling and Rendering



ReferencesFundamentals of Computer Graphics, 3rd ed. Shirley

and MarschnerComputer Graphics : Principles & Practices, AddisonWesley Longman, 2nd edition in C, James D. Foley,Andries van Dam, Steven K. Feiner, John F. Hughes

Computer Graphics with OpenGL, Third Edition, DonaldHearn and M. Pauline Baker, Prentice Hall, 2004

http://www.bookpool.com/ and the Library. Most of above books & more are found in this website

http://www.bookpool.com/

http://www.bookpool.com/



Topic 1: INTRODUCTIONComputer graphics refers to the study of digital synthesis and manipulation of visualcontent and interaction with it

This involves creation, storage and

manipulation of models and imagesSuch models come from diverse and expanding setof fields including physical, mathematical, artistic,biological, and even conceptual (abstract) structures.



Graphics

Modeling:

Defining objects in terms of primitives,coordinates and characteristics

Storage:

Storing scenes and images in memoryand on disk

Manipulation:

Changing the shape, position andcharacteristics of objects



Contd.

Rendering:

• Applying physically based procedures togenerate (photorealistic) images from

scenes (using lighting and shading)Viewing:

• Displaying images from various view

points on various devices



Graphics

William Fetter coined term“computer graphics” in 1960 todescribe the new design methodshe was pursuing at Boeing

He Created a series of widely

reproduced images on pen plotterexploring cockpit design, using 3Dmodel of human body.



Contd.“Perhaps the best way to define

computer graphics is to find outwhat it is not. It is not a machine. Itis not a computer, nor a group of computer programs. It is not theknow-how of a graphic designer, a

programmer, a writer, a motionpicture specialist, or a reproductionspecialist.

Computer graphics is all these – aconsciously managed anddocumented technology directedtoward communicating informationaccurately and descriptively.”

Computer Graphics, by William A.

I t ti C t



Interactive ComputerGraphics

Here User controls contents,structure, and appearance of

objects and their displayedimages via rapid visualfeedback

Basic components of aninteractive graphics system

input (e.g., mouse, tablet and-



Contd.display/output (e.g., screen,paper-based printer, videorecorder…)

First truly interactive graphicssystem, Sketchpad, pioneered

at MIT by Ivan Sutherland for his1963 Ph.D. thesis

Used TX-2 transistorized“mainframe” at Lincoln Lab

M it f C t



Merits of ComputerGraphicsIts a natural means of communication with thecomputer

Used in design, implementation and construction

Flexible in picture manipulation. We can makeboth concrete and synthetic pictures

Allows changing form of images not confiningimages to static forms only

It is applied in update dynamics



advantages

1. Image Reproducibility:

In a technical journal printed in black andwhite, fully shaded three-dimensionalgeometry may not print well. Forexample, photographic images do not

copy or fax as well as line art images.2. Medical Visualization: Researchers are focusing on providingartistic algorithms, which can be

manipulated interactively, for real timevisualizations of volume data. A goodexample is the



Contd.

visualization of electric fields inside the human body.

3. Communication of Abstract Ideas: The human visual system expects realistically

rendered characters to behave realistically.

Therefore, nonphotorealistic animation can be usedto express ideas beyond the physical and logicalnorm, in a way that is acceptable to a generalaudience. An example of this is force diagramsused in physics textbooks.



Contd.4. Evoking the Imagination:

Simple line drawings can communicate abstractideas in ways that a photograph cannot. In aphotorealistic image, everything in the scene isrendered in fine detail, leaving little to theimagination. In comparison, by not depictingevery detail, a nonphotorealistic image allowsthe viewer to share in the interpretive process.5. Animation: When creating an animation it is necessary tofocus the attention of the audience on the



Contd.relevant actions and elements in the scene. A

viewer inspecting the fine details of aphotorealistic scene can miss the big picture.Most nonphotorealistic techniques employ aneconomy of line, limiting the detail in a scene,which makes directing the attention of the

viewers easier for an animator.

6. Compression:

By not depicting all the detail required for

photorealistic images, nonphotorealistically



Contd.rendered computer graphics images

typically take less time to create, can berendered to the screen faster, and use lessstorage space. For example, half-toneimages yield the same shape from shading

cues as traditionally rendered computergraphics images when viewed from adistance. However, the half-tone imagesrequire between one tenth and one one-

hundredth of the storage space.



Contd.7. Communication of Design or Process

Completeness:

Photorealistic rendering implies an exactnessand perfection that may overstate thefidelity of the simulated scene to aphotograph. Artistic computer graphics canaid a viewer in understanding that the imagethey see is only an approximate depiction of a scene. An excellent example of this

phenomena is architectural rendering.Architects have found that on-site buildingconditions and variations in regional



Contd.building codes can lead to last minute changes

in building plans. If clients are shown realisticimages of the proposed building these lastminute changes can come as a shock, leadingto angry, disappointed clients. However, if theclients are shown nonphotorealistic images of the proposed building clients tend to acceptthe design process as incomplete and theplans as changeable. Therefore, the clientsusually accept on-site changes..



GraphicsComputer Aided Design (CAD)User InterfacesOffice Automation and Electronic PublishingEntertainmentSimulation and Animation for ScientificvisualizationPlotting in Business, science and technologyArt and CommerceProcess ControlCartography Trainings and Education



.Design (CAD)

In CAD, interactive graphics areused to design components andsystems of mechanical, electrical,

eloctromechanical and electronicdevices, including structures likebuildings aircraft etc

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2. User Interfaces (UIs)

Most applications that run on PCs,workstations and even in terminals

attached to network servers haveUIs that rely on point and clickfacilities to allow users do what

they want (select menu items,icons, and objects on the screen)for fast processing and feedback.

An example is in ATM terminals,



3. Office Automation andElectronic Publishing This allows for creation anddissemination of information.

Office tools like word processors,presentation and spreadsheet makeit easier for integration of graphics in

order to come up with easily seenand presentable documents andreports

Display of charts, graphs and other



4. Entertainment

Television commercials featuringflying logos and more exotictrickery have become common,

just as special effects in movies arebeing seen. Computer graphicsprovide mechanisms to model

objects and represent light andshadows

A i ti f S i tifi



Animation for ScientificVisualization

Scientists, engineers, medicalpersonnel, business analysts etc

often need to analyze largeamounts of information or to studythe behavior of certain processes.

Medicine uses this technique tomodel and study physical functionsin order to design artificial limbs

and to plan and practice surgery



Contd.

Graphics is used in this field toprovide an accurate representation

of parts and systems in the areasapplied. The coloration, and waveforms portrayed are brought out by

the graphical design

6 Pl tti i B i



6. Plotting in Business,Science and Technology This is used to present conciselyand meaningfully, the trends and

patterns gleaned from data so as tofacilitate informed decision making

Creating 2D and 3D graphs of

mathematical, physical andeconomic functions like histograms,task scheduling charts, inventory

and production chart.



7. Art and Commerce

Here computer graphics is used incomputing environment to producepictures that express a message

and attract attention.Personal computers teletext andvideotext terminals in public places

offer much simpler but informativepictures that make users orientthemselves and make choices



8. Process Control

In real scenarios like refineries,computer graphics is used inscreens/displays to show data from

sensors attached to the criticalsystem component so thatoperators can respond to

problematic conditionsFor instance in military,commanders use graphics to obtain

scenarios from the battle fields on



9. Cartography

In cartography, this is used toproduce both accurate and

schematic representations of geographical and other naturalphenomena from measurement

data.Examples include geographicalmaps, relief maps, exploration

maps for drilling and mining,



.Education

Computer generated models of physical, financial and economic

systems are often used aseducation aids. Models of physical systems, physiological

systems, population trends orequipment can help traineesunderstand the operations of a

system. For some training



Contd.Examples of such specializedsystems are simulators for practicesessions or trainings of ship

captains, aircraft pilots, heavyequipment operators and air trafficequipment traffic control

personnel.Some simulators may not havevideo screens eg. Flight simulator

with only control panel for



Contd.

Just like in trainings, educationalliteratures can be accuratelyrepresented using graphics. Humanskeleton, liver, lungs and forumsamong others are despicable bygraphics



10. Contd.



ApplicationsPaint Programs. This help in creation of roughfreehand drawings and always stored in bitmaps. Itinclude MS Paint, Paint shopPro

Illustration/Design (Draw) Programs. Supportsmore Advanced features than paint especially in

drawing curves. Its images are usually stored invector-based formats.eg. Photoshop, illustrator etc

Animation Software. Enables Chaining and



sequencing of series of images to simulatemovement. Used mostly in movie industry. Eg.

Morpheus Photo Animation Suite, ProjectDogwaffle, MapScenes Systems etc

Desktop Publishing Software. Helps increation of newsletters, advertisements, books

etc with full set of word processing and otheroffice features and fine control of graphics

Presentation Graphics software. Allows youto create charts & other types of images forslide shows and reports

Graphics software



Graphics softwareApplicationsDimensionality Type of Interaction

Role of the PictureRelationship between objects andtheir Pictures

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