Prepared by Abzamiyeva Laura Candidate of the department of KKGU named after Al- Farabi
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Transcript of Prepared by Abzamiyeva Laura Candidate of the department of KKGU named after Al- Farabi
Prepared by Abzamiyeva LauraCandidate of the department of KKGU
named after Al-FarabiKizilorda, Kazakstan 2012
“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 ?
→ 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
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
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
Reference: → http://www-
→MapServer
→OpenLayers