B.Sc. Multimedia ComputingMedia Technologies

Vector Graphics

Agenda

Characteristics of Vector Graphics Vector Graphic Formats Pros & Cons Scalable Vector Graphics (SVG)

Vector Graphics

Vector graphic files contain mathematical descriptions of one or more image elements, which are used by the rendering application to construct a final image.

Vector files are thus said to be made up of descriptions of image elements or objects, rather than pixel values.

Example Formats

Microsoft Windows metafile .WMF Corel Computer Graphics

Metafile .CGM Adobe Systems Macromedia Autodesk Data Exchange .DXF Macromedia Shockwave Flash .SWF

Vector Graphics - Pros Vector files are useful for storing images composed

of line-based elements such as lines and polygons, or those that can be decomposed into simple geometrical objects, such as text.

More sophisticated formats can also store 3D objects such as polyhedrons and wire-frame models.

Vector data can be easily scaled and otherwise manipulated to accommodate the resolution of a spectrum of output devices.

Vector Graphics - Pros

Many vector files containing only ASCII-format data can be modified with simple text editing tools. Individual elements may be added, removed, or changed without affecting other objects in the image.

It is usually easy to render vector data and save it to a bitmap format file, or, alternately, to convert the data to another vector format, with good results.

Vector Graphics - Cons Vector files cannot easily be used to store extremely

complex images, such as some photographs, where color information is paramount and may vary on a pixel-by-pixel basis.

The appearance of vector images can vary considerably depending upon the application interpreting the image. Factors include the rendering application's compatibility with the creator application and the sophistication of its toolkit of geometric primitives and drawing operations

Vector Graphics - Cons

Vector data also displays best on vectored output devices such as plotters and random scan displays. High-resolution raster displays are needed to display vector graphics as effectively.

Reconstruction of vector data may take considerably longer than that contained in a bitmap file of equivalent complexity, because each image element must be drawn individually and in sequence.

Random v Raster

Scaleable Vector Graphics SVG is a language for describing two-dimensional

graphics and graphical applications in XML Scaleable means extendable

Interaction - mouse events Animation - animated components

SVG still in Development Development by WC3 - SVG Web Consortium Working

Group Group membership made up of interested parties from

computer graphics community et al. Representatives from companies including:

Adobe Systems Microsoft Corporation Macromedia Sun Microsystems Autodesk Corel Nokia

SVG Group at http://www.w3.org/Graphics/SVG/Overview.htm8

Reference Guide

Encyclopedia of

Graphics File Formats

Second Edition

James D. Murry and

William VanRyper

O'Reilly & Associates 1996

ISBN 1-56592-161-5

A Word on Standards

De-Facto Standard ‘by fact’ A format, language, or protocol that has

become a standard not because it has been approved by a standards organization but because it is widely used and recognized by the industry as being standard; e.g .SWF - adopted by fact of use.

De-Jure - ‘by law’ Adopted by agreement e.g SVG development

within framework of W3C Working Group.