Institute for Visualization and Perception Research 1 © Copyright 2000 Haim Levkowitz Introduction...

Institute for Visualization and Perception ResearchIVPR 1

© Copyright 2000 Haim Levkowitz

Introduction (Foley & Van Dam Ch 1)

• Uses of computer graphics …

• Some basic terms and concepts …

• Image processing and synthesis …

• Classification of applications …

• HW & SW for computer graphics …

• Advantages of interactive graphics …

• Conceptual framework for interactive graphics ...



Uses of Computer Graphics …

• User interfaces• Interactive plotting: business, science, technology, art• Cartography• Medicine• Computer-aided drafting and design• Multimedia systems• Simulation, animation, visualization• Office automation and electronic publishing



Some Basic Terms and Concepts …

• Interactive

• Bitmap

• Bitmap graphics

• Pixels, pels

• Windows, window manager

• Direct manipulation



Image Processing & Synthesis …• Synthesis

• Image processing

• Picture processing

• Reconstruction of processing

• Image enhancement

• Pattern detection and recognition

• Scene analysis and computer vision

• Optical Character Recognition (OCR)

generate initial display from modeldo {

enable selection of commands or objectswait for user selection /* Wait state */switch (on selection) {

process selectionupdate model and screen

}}while (!quit)



Classification of Applications …

• Dimensionality of object & kind of picture …

• Type of interaction

• Offline plotting

• Interactive plotting

• Role of the picture



Dimensionality of object & kind of picture

• 2D

• Line drawing

• Gray scale image

• Color image

• 3D

• Line drawing (wireframe)

• Line drawing, with various effects

• Shaded, color image with various effects



HW & SW for Computer Graphics …

• Large, interactive programs

• Nonportable vs. portable software

• Output technology …

• Input technology …

• Software portability and graphics standards ...



Output technology

• Vector …

• Raster displays ...



Vector …• Stroke, line drawing,

calligraphic displays• Characters• Display list, display program• Vector generator• Random scan• Refresh• Refresh buffer



Raster displays …

• Primitives

• Raster lines

• Raster ...

• Bitmap, pixmap

• Frame buffer

• Scan-converted

• Raster image processor

• Aliasing, antialiasing



RasterVector vs. raster ...



Vector vs. raster



Input technology …

• Text: Keyboard

• Locator: Pointer / Mouse / Tablet

• Higher dimensions

• Polhemus

• Spaceball



Software portability and graphics standards ...

• Device-independent

• Application-program portability

• Device-dependent

• Core Graphics System

• Segments

• Structures



The advantages of interactive graphics …

• Motion dynamics

• Update dynamics



Conceptual framework for interactive graphics …

• Overview …

• Modeling …

• Display …

• Interaction Handling …



Overview

• Application program

• Application model

• Graphics system

• What

• How

• Output transformation

• Input transformation



Modeling …

• Application model

• Application database

• Primitives

• Attributes

• Connectivity

• Geometrical interpretation



Display …

• Graphics subroutine library or package

• Logical display device

• Locator

• Sample vs. event



Interaction Handling …

• Event-driven loop

Institute for Visualization and Perception Research 1 © Copyright 2000 Haim Levkowitz Introduction...

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