Geographic Information System (GIS)
Introduction
A Geographic Information System (GIS) is a framework designed to capture, store, manipulate, analyze, manage, and present all types of geographical data. The term GIS is often used to refer to software that presents data in a spatial context, allowing users to visualize and interpret data in ways that reveal relationships, patterns, and trends. GIS technology can be used for scientific investigations, resource management, asset management, environmental impact assessment, urban planning, cartography, criminology, history, sales, marketing, and logistics.
History
The concept of GIS has its roots in the practice of cartography and the desire to automate map production. The first known use of the term "Geographic Information System" was by Roger Tomlinson in 1968 in his paper "A Geographic Information System for Regional Planning". Tomlinson is also acknowledged as the "father of GIS".
Components of GIS
A GIS system is typically composed of data, software, hardware, and users. Each of these components plays a crucial role in the functioning of a GIS system.
Data
Data in GIS are often referred to as layers, coverages, or themes. Layers of data are organized to create a map or a 3D scene. There are two main types of data that are used in GIS: spatial data and attribute data.
Spatial Data
Spatial data, also known as geospatial data or geographic information, is the data or information that identifies the geographic location of features and boundaries on Earth, such as natural or constructed features, oceans, and more. Spatial data can be classified into two broad categories: vector and raster.
Vector Data
Vector data is composed of vertices and paths. The three basic symbol types for vector data are points, lines, and polygons (areas). Each of these is comprised of discrete geometric locations (x, y values) that are connected in a particular order.
Raster Data
Raster data is cell-based and is often used to represent continuously varying phenomena such as elevation, temperature, or aerial imagery. Each cell is part of a grid and contains a value representing the feature or phenomenon at that grid location.
Attribute Data
Attribute data, also known as tabular data, is the information linked to the spatial elements of a GIS. This data is usually in table format and connected to the spatial data through a common identifier.
Software
GIS software provides the functions and tools needed to store, analyze, and display geographic information. There are numerous GIS software providers, including ESRI, MapInfo, and QGIS. The software can be desktop-based, server-based, or web-based.
Hardware
Hardware for GIS includes the computing equipment used to run the GIS software and store the data. This can range from a single desktop computer to a network of computers or servers.
Users
Users are the people who use the GIS to analyze geographic data and make decisions based on that analysis. They can range from professionals in the field to members of the public using web-based applications.
GIS Data Models
GIS data models are a set of rules and constructs for representing objects and phenomena in a GIS. There are two primary types of data models: vector and raster.
Vector Data Model
In the vector data model, information about points, lines, and polygons is encoded and stored as a collection of x,y coordinates. Vector data is used to represent discrete objects such as a house, a road, or a lake.
Raster Data Model
The raster data model represents information as a cell matrix that covers the entire study area. Each cell has a value that corresponds to the feature it represents. This model is commonly used for representing continuous phenomena such as elevation or temperature.
GIS Analysis
GIS analysis is the process of using a GIS to derive new information from existing data. GIS analysis functions use the spatial and non-spatial attribute data to answer questions about real-world. There are several types of GIS analysis, including overlay analysis, network analysis, and spatial statistics.
Overlay Analysis
Overlay analysis is a group of methodologies applied in optimal site selection or suitability modeling. It involves the layering of multiple data sets to create a composite map.
Network Analysis
Network analysis is used to evaluate routes and optimize routing conditions. It is commonly used in transportation planning, logistics, and emergency service planning.
Spatial Statistics
Spatial statistics include a range of techniques for analyzing spatial data. The results can provide additional insight into the data that may not be immediately apparent from looking at a map.
Applications of GIS
GIS technology is used in a wide variety of fields due to its ability to analyze and visualize spatial data. Some of the key applications of GIS include urban planning, environmental management, transportation, and public health.
Urban Planning
Urban planners use GIS for land use planning and policy making. They can visualize and analyze the spatial patterns of various socio-economic activities to make informed decisions.
Environmental Management
Environmentalists use GIS for studying the impact of human activities on the environment. It helps in monitoring and managing natural resources and wildlife.
Transportation
GIS is used in transportation for route planning, traffic modeling, accident analysis, and more. It helps in optimizing routes for different modes of transportation.
Public Health
Public health professionals use GIS to track disease outbreaks, plan health services, and identify environmental health issues.
Future of GIS
With advancements in technology, the future of GIS is moving towards more integrated systems. GIS technology is becoming more prevalent and accessible, and as a result, its applications are becoming more diverse. Future trends in GIS include increased use of real-time data, 3D data modeling, and cloud computing.