10 1 introduction (1)

8/8/2019 10 1 Introduction (1)

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Computer Graphics:

Course Intro.,

History, ContextAngel, Chapter 1

CSCI 6360/4360


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Computer Graphics, Fall 2010

Angel, page 1:

Perhaps the dominant characteristic

of this new millennium is howcomputer and communication

technologies have become

dominant forces in our lives.

Not a bad place to be sometimes we forget


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Computer Graphics, Fall 2010

Angel, page 1:

Perhaps the dominant characteristic of this new

millennium is how computer and communication

technologies have become dominant forces in our

lives.

Computer graphics is concerned with all aspects of

producing pictures or images using a computer.

allaspects

Hardware

Software

Applications


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Applications: Movies


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Applications: Games


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Applications: Visualization


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Apps: Computer Aided Design


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App: Virtual and Augmented Reality


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Apps: New Information Spaces


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Applications: Art


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Elements of

ComputerGraphics

UTPA:Computer Graphics

Visualization

Interactive Systems

Human Computer Interaction

Programming systems

-windows

-graphics

Hardware and

graphics engines

3-D

ViewingTransformation

Representation of

curves and surfaces

Models,

(Foley et al. term)

Drawing

Algorithms

Lights

Rendering

User, i.e., Human

Interaction Perception Information

An illusion:

analog world

represented

digitally

Programming is a craft

Open

System

DisplayClosedSystem


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Computer Graphics

Angel, p. 1 Computer graphics is concerned with all aspects of producing

pictures or images using a computer.

Allaspects

Hardware Software

Applications

Foley et al., creation, storage and manipulation ofmodels and images

Models come from a diverse and expanding set of fieldsincluding physical, mathematical, artistic, biological, andconceptual (abstract) structures.

Historically, there was a hard line, not so much anymore


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Origins

William Fetter coined term computer graphics New design methods pursuing at Boeing, early 1960s, graphic designer

Created a series of widely reproduced images on a plotter exploring cockpitdesign using a 3D model of a human body

Boeing man


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Origins

William Fetter coined term computer graphics New design methods pursuing at Boeing, early 1960s, graphic designer

Created a series of widely reproduced images on a plotter exploring cockpitdesign using a 3D model of a human body

Boeing man

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 ofcomputer programs. It is not theknow-how of a graphic designer, aprogrammer, a writer, a motionpicture specialist, or areproduction specialist.

Computer graphics is all these --a consciously managed anddocumented technology directedtoward communicating informationaccurately and descriptively.

Computer Graphics, William A.

Fetter, 1966


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Even More Fundamentally

Computing is about insight, notnumbers

and a lot of people got it, rightaway

Hamming, R.W., Numerical Methods

for Scientists and Engineers, 1962

Goals of insight:

Discovery

Decision making

Explanation

And, heck, computer graphics arefun

1962, PDP-1, Spacewar


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Computer Graphics, Angel Ex.

Where did this imagecome from?

What hardware/softwareto produce it?

Application: The object is an artists

rendition of the sun for ananimation to be shown in adomed environment

(planetarium)

Software: Maya for modeling and

rendering but Maya is built ontop ofOpenGL

Hardware: PC with graphics card for

modeling and rendering


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Interactive Computer Graphics

Interactive computer graphics Where computation, human, and machine come together

User controls contents, structure, and appearance of objects and their displayedimages via rapid visual feedback

Graphics is/are pervasive:

Text (character) mode vs. graphics mode (ever heard of something called DOS, or Unix command line?)

Dominant display and interaction paradigm for interaction

Direct manipulation interfaces require graphics

The two contrasts of a) text with graphics and b) batch with

interactive describe the context of interactive computer graphics Sutherlands landmark work described the ideas


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Interactive Computer Graphics

Input devices

Output devices

Image formed in FB

Basic components of an interactive graphics system: Input (e.g., mouse, tablet and stylus, force feedback device, scanner...)

Processing (and storage)

Frame buffer (raster) more next time

Display/output (e.g., screen, paperbased printer, video recorder...)


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Raster Architecture (next time)

Early systems Used part of system memory (system

address space) for frame buffer

Single CPU set frame buffer and performedgraphics system commands

Current systems Separate processor gets cmds from CPU

Graphics Processing Unit (GPU) In hardware (firmware):

Scan conversion

Texturing

Dedicated texture memory Lighting calculations

3D transformation calculations

GPU more power than CPU Interesting implications!


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Cg Software Architecture, APIs

Graphics APIOpenGl (no win sys func)DirectX

Window system APIMS windowsX tools

CPUGPU

Graphics Processing Unit


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Software Arch., Window System

Application ProgsE.g., student programsMS Excel, etc.

Tools: UI Program.MFC, Swing,Qt (widget toolkit and more)



CPUGPU



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Software Arch., Graphics



GLUTOpenGL Utility Toolkit


CPUGPU


Tools: Vis. Program.VTKs3s


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Software Architecture, All


Tools: GraphicMaya3ds





CPUGPU




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Software Architecture (save)


Tools: GraphicMaya3ds





CPUGPU




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Context of Computer Graphics

Graphics is key enabling technology in evolution of computingenvironments: Graphical user interfaces

Visual computing,

e.g., desktop publishing, scientific visualization, information visualization

Hardware revolution drives everything ~ every 18 months, computer power improves by factor of 2 in price/performance

Moore's Law

and exponential growth generally things are different

Graphics memory and network speeds are on even faster

exponentials graphics chips in particular have major improvements every six to nine months

e.g. Sony Playstation 2, Nintendo GameCube, Xbox, nVidia GeForce 3


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On Exponential Growth

Some technology is exponential in advancement

Other things are not

E.g., software and


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Taking Advantage ofExp. Growth


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Taking Advantage ofExp. Growth?


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Moores Law Dead?

?


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Parallelism and Moores Law

Moores law is alive and well for graphics

Because lends itself to parallelization

Pipeline architecture works well with current approach to cg

~ Now, gpu processing power > cpu processing power in

commodity pcs!

How to use parallel, here, gpu, architectures is not a new question

Cf. Nvidia gpu programming language


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CSCI 4360 and 6360, Fall 2010

Syllabus, . about the course Student background

Impacts programming assignments, pace, presentations,


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Course - Schedule of Topics

Graphics systems and models Thinking and speaking optically and computer-graphically

Graphics programming today, OpenGL programming first! Input and interaction, and other things throughout

Geometric objects and transformations Nuts, bolts and coordinate systems or numbers, pixels, and math

Viewing Pixels and looking at things

Lighting and shading Illumination models good (and fast) enough

From vertices to fragments Getting lines and points on the screen and just the right ones

Discrete techniques Buffers, bits, and textures

Project demonstrations


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Computer Graphics History

Computer graphics all aspects

Hardware, software, applications

Hardware

Graphics processing

SAS and processor, separate processing in workstation, separate processor in commodity, GPU > CPU

Display Paper & oscilloscope, vector based, raster based, lcd/led commodity 3d

Software

Graphics package, graphics api Custom, 80s and 90s starts, standardization ofOpenGL

Applications

Use of graphics in application, e.g., Autocad

Use for graphics creation, e.g., Maya


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Origins: Sutherlands Sketchpad, 1/2

First truly interactivegraphics system, Sketchpad A fairly sophisticated paint (or

drawing) program

MIT, Ivan Sutherlands 1963

Ph.D. thesis Sketchpad, A Man-Machine

Graphical CommunicationSystem

Available:

www.cl.cam.ac.uk/techreports/UCAM-CL-TR-574.pdf

Video:

www.youtube.com/watch?v=mOZqRJzE8xg

Among most importantworks in computer science

Ivan Sutherland using Sketchpadin 1963CRT monitor, light pen and function-key panel


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Origins: Sutherlands Sketchpad, 2/2

Almost all the keyelements of an interactivegraphics system areexpressed in the first

paragraph of Sutherland'sthesis!: The Sketchpad system uses drawing

as a novel communication medium fora computer. The system contains input,output, and computation programswhich enable it to interpret informationdrawn directly on a computer display.Sketchpad has shown the mostusefulness as an aid to theunderstanding of processes, such asthe motion of linkages, which can bedescribed with pictures. Sketchpadalso makes it easy to draw highlyrepetitive or highly accurate drawingsand to change drawings previously

drawn with it... (Sutherland, 1963)


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Computer Graphics: 1950-1960

Character Displays (1960s - now) Display: text plus alphamosaic pseudo graphics

Object and command specification: command line typing

Control over appearance:

coding for text formatting, e.g., .p =paragraph, .i 5 =indent 5

Application control: single task

Vector Displays (1963 - 1980s) Display: line drawings and stroke text; 2D and 3D transformation hardware

Object and command specification: command line typing, function keys, menus

Control over appearance: pseudo WYSIWYG

Application control: single or multitasked, host satellite distributed computing


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Wireframe graphics Draw only lines

Sketchpad

Display Processors

Storage tube

DE

C PDP-1, below Early CRT displays based on

oscilloscopes

Primitive (custom) software

But, beginning of advances in cg

algorithms

Interactive cg possible at high end


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FYI - Display Processor

Really old school technology, but some terminology remains, e.g.,display list

Rather than have the host computer try to refresh display, use a

special purpose computer called a display processor(DPU)

Graphics stored in display list (display file) on display processor

Host compiles display list and sends to DPU


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Direct View Storage Tube

First real cg capable display Created by Tektronix

Did not require constant refresh

Standard interface to computers Allowed for standard software

Plot3D in Fortran

Relatively inexpensive

Opened door to use of computergraphics for CAD community


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Raster graphics todays display paradigm Map pixel to memory location (vs. vector display list)

bitmap really bytemap or wordmap or

Memory cost allowed

Back then, 64k words total, not uncommon

Beginning of graphics standards IFIPS

GKS: European effort

Becomes ISO 2D standard

Core: North American effort

3D but fails to become ISO standard

It was a real mess at least compared to now

(Scientific) Workstations and PCs Strong, clear distinctions, that have at least blurred now


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Raster Graphics, 1970-1980

Image produced as an array (the raster) of picture elements (pixels)in the frame buffer Map pixel to memory location (vs. vector display list)

Can now go from lines and wire frame images to filled polygons

Many fundamental algorithms developed E.g., Phong shading


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PCs and Workstations

Although we no longer make a (clear) distinction betweenworkstations and PCs, historically they evolved from different roots

Early workstations characterized by Networked connection: client-server model

High-level of interactivity

Early PCs included frame buffer as part of user memory

Easy to change contents and create images

And, for speed, often programmed directly into frame buffer fromapplication

Vs. using a software layer, such asOGL


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2D bitmap raster displays for PCs and workstations (1972 XeroxPARC - now) Display: windows, icons, legible text and ``flat earth'' graphics.

late 60's saw first use of raster graphics, especially for flight simulators.

Object and command specification: minimal typing via WIMP (Windows, Icons, Menus, Pointer)

GUI (Graphical User Interface): point and click selection of menu items and objects, widgets and direct manipulation

(e.g., drag and drop), the messy desktop metaphor

Control over appearance: WYSIWYG (which is really WYSIAYG, What You See Is All You Get)

Application control: multitasking, networked clientserver computation and window management

(even X terminals)


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Photorealism feasible E.g., ray tracing and other computationally expensive techniques

smooth shading environment mapping bump mapping


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Ray Tracing

Consider how light from a source might be modeled Follow every ray from the source, to the objects, and see what goes to viewer

Somewhat more computationally feasible (though still expensive) is

to run things backward from cop to objects to illumination source


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Computing and Graphics - Now

Digital Convergence: Merging of digital television and distributed computing, consumer electronics:

settop computers (e.g., for Interactive TV, VideoOnDemand)

The Internet and Internet appliances Radio, movies,

Embedded computing Information appliances, Personal Digital Assistants aka telephones

Ubiquitous/pervasive/invisible computing, active badges, 100's ofdevices/person

Social computing

Chips are key in graphics: powerful, inexpensive processing Again, advances driven by Moore's Law


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Application Distinctions

Two basic paradigms for computer graphics:

1. Sampled-based graphics: Discrete samples are used to describe visual information

Pixels can be created by digitizing images, using a samplebased paintingprogram, etc.

Often some aspect of the physical world is sampled for visualization, e.g.,temperature across the US

Example programs: MS Paint, Adobe Photoshop

2. Geometry-based graphics: A geometrical modelis created, along with various attributes, and is then

sampled for visualization (this process is called rendering) Often some aspect of the physical world is visually simulated, or ``synthesized''

Example 2D programs: Adobe Illustrator, Macromedia Freehand, Corel CorelDRAW!, Microsoft PhotoDraw

Example 3D programs: Alias/Wavefront Studio and Maya, Avid's SoftImage 3D, Autodesk's AutoCAD and 3D

StudioMax, Autodesys FormZ


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Sampled-based Graphics, 1

Images are made up of a grid of discrete pixels for 2D ``pictureelements''

Pixels are point locations with associated sample values usually of light intensities/ colors, transparency, and other control information


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Example of Sampling

In a continuous/analog, e.g., photographic image Color value is measured at every grid point and used to color a corresponding

grid square

E.g. at right: 0 = white, 5 = gray, 10 = black

Here, poor (low resolution) sampling and image reconstruction

method creates a blocky image


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Advantages Disadvantages of Sampling

Advantages:1.Once image is defined in terms of colors at (x, y) locations on grid, can changeimage easily by altering location or color values

e.g., if we reverse our mapping above and make 10 = white and 0 = black

2. Pixel information from one image can be copied and pasted into another,replacing or combining with previously stored pixels

Disadvantage: WYSIWYG (What You See Is What You Get):

There is no additional information: no depth information can't examine scene from a different point of view at most can play with the individual pixels or groups of pixels to change colors, enhance contrast, find

edges, etc.


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Geometry-Based Graphics, the Model

A modelcaptures the salient features (data, behavior) of thing/phenomenonbeing modeled data includes geometry, appearance attributes...

similarity to OOP notions

Real: some geometry inherent physical (e.g., actual object such as a pump)

nonphysical (e.g., mathematical function, weather data)

scientific visualization

Abstract: no inherent geometry, but for visualization organizational (e.g., company org. chart)

quantitative (e.g., graph of stock market data)

information visualization

Modeling, you may recall from other cs courses, is coping with complexity

Then, given some model, reconstruct in graphics the visual representation E.g., from equation of sphere compute points

Through 3D computer graphics, for first time have abstract, easilychangeable 3D forms Revolutionized working process of many fields science, engineering, industrial design,

architecture, commerce, entertainment, etc. (this may be important)


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