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GIS (Basics)

GIS or Geographic Information System:

  • Collectes information of the location or earth for the decision making
  • Computer based system to for geo reference data
  • Capturing, storing, retrieving, analyzing and displaying data positional referenced to earth


Raw Data  > Data Input > Database Managment > "Manipulation" > Analysis > Output and Visualization

Geographic Data

Spatial Data: shape, size and structure of the location; contains polygonal information; data may be vector or raster

Non-spatial data (Attribute or tabular data): information about the attributes such as population, presented in tabular information with different attributes

Both spatial and non spatial data gives the knowledge on the earth surface and what it contains; further helping in understanding of the temporal and spatial relationships.

The components of GIS include hardware, software, data and people. The input data can me multiple for GIS.

Data Models:

~ Helps in the representation of the the earth surface or the real world ~

Vector Model: point, line and polygon feature

Raster Model: in pixel format, according to the reflectance, 

Dataset preparation:

* Generating model based on the problems

* Data Collection (primary sources or secondary sources), Input and Storage

* Manipulation, Processing of the data and Analysis

* Visualization and Usage

The data preparation steps can have differnent errors. 

Minimizing errors maximizes data quality. Data quality maintains accuracy, precision, completeness and consistency, and meets the requirements of the user, while the producer must have meet the required specifications. The data quality may be judged by the requirements of the user and purpose. Data quality is an important issue.

DBMS ~ Database Management System

DBMS controls repetition of the data while restricting the access. The scurity, recovery and backup are easily possible. Database includes attribute tables, records and fields,

GIS has the ability to answer: positional, conditional, temporal, pattern and trends information related queries. These are done by different methods. Analysis are different according to data models: vector or raster based models.


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