Prepared by Abzamiyeva LauraCandidate of the department of KKGU

named after Al-FarabiKizilorda, Kazakstan 2012

Object

• Introduction of GIS

• Data modeling

“GIS is a computer-based system that provides the following four sets of capabilities to handle geo-referenced data:

1. Input

2. Data management (storage and retrieval)

3. Manipulation and analysis

4. Output.”

(Aronoff, 1989)

What is GIS ?

GIS Functional Modules

Database

Query and Analysis

Output and Visualization

Data Input

→ https://www.e-education.psu.edu/natureofgeoinfo/book/export/html/1604

What does GIS?

GIS deals with objects, their attributes, and the relationships among the objects.

The objects are stored in a database using geometric primitives (volumes, areas, lines, points), their attributes and the relationships between them (topology).

Characteristics of Geographic Data

Spatial data: features orientation shape, size

& structure Non-Spatial data: Information about various

attributes like area, length &

population

spatial reference attributes spatial relationships temporal component

Characteristics of Spatial Data

where?what?how?when?

Data ModelData model represents the linkages between the real world domain of geographic data and the computer or GIS representation of these features. It helps (Marble, 1982)

• To organize a systematic file structure

• Abstracts the real world into properties which are perceived by a specific application

How to represent the really data?

?

GIS structures as representations of reality

Two approaches have been widely adopted for representingthe spatial & attribute information within a GIS

• A composite model (raster)

• Geo-relational model (vector)

Implementation Models

Field View tessellation (raster,

grid)

– simple data structure– difficult to represent

topology– suitable for image

processing functions

Object Viewvector (topological vector

model)

efficient representation of topology

complex data structure certain functions are

difficult to implement

Real (and Virtual) World Models

10100100111

Maps Databases

VisualizationRepresentationGeneralization

Storage

Best known conventional modelTwo-dimensionalStaticVisualization as their major functionSmall-scale = less detail, larger area

(e.g. 1:1.000.000)Large-scale = more detail, smaller area

(e.g. 1:10.000)Generalization (scale-dependant)

Maps

Databases

Store representations of spatial phenomena in the real world

Data models are languages used to define a database

The complete database definition is the database schema

Spatial databases are scaleless and seamless

spatial data models two fundamental approaches:

raster model vector model

a raster view of the world...

Tessellation

RasterFeatures

Sampling

raster model

The entity information is explicitly recorded for a basic data unit (cell, grid or pixel)

vector modelIn a vector-based GIS data are handled as:

Points X,Y coordinate pair + labelLines series of pointsAreas line(s) forming their

boundary (series of polygons)

line feature

area featurepoint

feature

vector model

vector model

layers in a raster model

Layer 1

Layer 2

Reference: → http://www-

→MapServer

→OpenLayers

THANK YOU !