Vector Graphics

Multimedia Technology

Object Orientated Data Types

• Created on a computer not by sampling real world information

• Details are stored on the attributes (properties) of each object that is stored in the file.

• Each object can be altered by changing its attributes…

Examples• Text

– A character in a text file can be given a different size, colour or font

• Drawing – A shape in a drawing can be given a different size or

fill colour

• 3D image– An object in a 3D image can be given a different

location, rotation or texture

Vector Graphics

• All data is stored as a group of objects within a file

• Each object can be edited individually without affecting any others

• All aspects of each object are decided by its properties (attributes)

• These files are basically a collection of objects with details about them. This means they can be stored as plain text files.

Object Orientated Data

Topic 5: Multimedia Technology

Recap

• Object Orientated Data– All data is stored as a group of objects within

a file– Details are stored on the attributes

(properties) of each object that is stored in the file.

– Each object can be edited individually without affecting any others

– These files are basically a collection of objects with details about them. This means they can be stored as plain text files.

Vector Graphics data

• A vector is a mathematical term for a line with a specific length and direction.

Vector Vs Bitmap

Scaling causes pixellation. Can be scaled to large sizes, keeping original quality.

Only the image as a whole can be edited.

Individual objects can be edited.

Are very difficult to convert to vector formats

Are easily converted to bitmap formats.

File sizes can be large. File sizes are relatively small.

Images can be very realistic (e.g. digital photograph).

Difficult to create realistic images

Vector Vs BitmapSize of image can be increased keeping quality and file size the same.

Increasing the image size needs re-sampling and increases the file size.

Only individual objects can be edited (it is sometimes impossible to edit only part of the object).

Same appearance in all systems, regardless of hardware or software.

Dependent on output hardware or software for appearance & quality.

Pixel level editing is allowed - allowing effects such as spray paint, blur, effects and so on.

Suitable for natural, hand-drawn looking, realistic images.

Suitable for graphic, unrealistic images and designs.

Attributes

• Attributes are the properties that determine what and how objects will appear

• These files can include a bitmap as a separate object…

Attributes

Object 3

Object 2

Object 4

Object 1

Object 6

Object 5

Object 7

Vector Graphics File Formats

Drawing : SVG

3D : VRML/WML

Additional Attributes for 3D images

• Surface texture – give surface definition

• Shadow – simulates direction of light

• Angle of rotation (to view from different angles)

• Z coordinate

File format for 3D vector image:VRML/WML