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8/8/2019 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]
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SAMPLING, MORPING ANDRENDERING
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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
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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
hi
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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
il hi
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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
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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
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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
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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
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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.
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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
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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
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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.
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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
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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-
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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
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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
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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
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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.
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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
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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
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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.
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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
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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..
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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
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.Design (CAD)
In CAD, interactive graphics areused to design components andsystems of mechanical, electrical,
eloctromechanical and electronicdevices, including structures likebuildings aircraft etc
LosAngel e
s
Airport
(BillJepso
n,UC)
B o e i n g
7 7 7
A i r p l a n e
( B o e i n g
C o r p o r a t i o n )
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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,
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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
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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
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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
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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
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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.
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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
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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
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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,
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.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
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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
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Contd.
Just like in trainings, educationalliteratures can be accuratelyrepresented using graphics. Humanskeleton, liver, lungs and forumsamong others are despicable bygraphics
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10. Contd.
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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
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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
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Graphics softwareApplicationsDimensionality Type of Interaction
Role of the PictureRelationship between objects andtheir Pictures