Introduction to GIS

 

Overview, History and concepts of GIS

Concepts of GIS

- Geographic Information System is a computerized system that facilitates collection, analysis and presentation of georeferenced or spatial data.
- GIS involves working with positional data that makes use of Earth’s surface as a reference.
- GIS application is the tool that allows the user to create interactive queries, analyze spatial information, edit data in maps and present the results in an interactive manner.

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History of GIS

- The term Geographic Information System was first used by Roger Tomlinson in his paper "A Geographic Information System for Regional Planning" in 1968.
- In 1960, the first operational GIS was developed in Canada by Federal Department of Forestry and Rural Development. It is known as Canada Geographic Information System (CGIS).
- In 1964, Laboratory for Computer Graphics and Spatial Analysis was formed at Harvard Graduate School of Design. The theoretical concepts on spatial data analysis were developed.
- By late 1970's, two public domain GIS systems known as MOSS and GRASS GIS were in development.
- By early 1980's, Environmental System Research Institute (ESRI), Computer Aided Resource Information System (CARIS) and Earth Resource Data Analysis System (ERDAS) emerged as commercial vendors of GIS software.
- In 1986, Mapping Display and Analysis System (MIDAS) was released as a first Desktop GIS product.
- In 1990, MIDAS was renamed as MapInfo for Windows operating system.
- By the end of 20th century, users started exploring GIS data over the Internet.

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Stages of GIS

1. Data Preparation and Entry:
- It is the first phase for GIS.
- The study phenomena is decided.
- All the geographic data related to the geographic phenomena under study are collected.
- The collected geographic data are then prepared by converting into the format that can be entered into the GIS system.

2. Data Analysis:
- It is the second phase of GIS.
- The collected data are reviewed and analyzed to discover hidden patterns within them.
- It includes various geographic data mining techniques.

3. Data Presentation:
- It is the final phase of GIS.
- The results obtained from the analysis phase are presented to the users of the GIS application.
- The results should be presented in efficient and understandable way.

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Functions of GIS

1. Integrated representation of geographic data
- The geographic data are represented in the easy and understandable manner.
- GIS makes use of various tools to represent the data in the form of point, line, polygon, topography.
- The collection of all of these representation provides the integrated view of the collected data.

2. Spatial analysis and visualization
- GIS is responsible to analyze the collected geographic data.
- Such analysis is helpful to determine the patterns within the data.
- GIS is also responsible to visualize the data using 2D and 3D visualization technique so as to present the analysis results to the users in efficient way.

3. Geographic data storage and management
- GIS is also responsible to store and manage the collected geographic data and obtained patterns or information.
- Such collection may lay roadmap to produce a new informative map of interest.

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Purpose and benefits of GIS

Purpose of GIS

- It allows to record a base map with a geospatial referencing system along with additional layers of other information.
- It provides statistical and analytical tools to analyze the recorded information.
- It facilitates visual representations of analyzed data that is used to reveal patterns and trends.

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Uses of GIS

- GIS is used to provide a visual representation of data in a mapped format from the stored data in a database
- It is used for proximity analysis. Proximity analysis is an analytical technique that is used to define the relationship between a specific location and other locations that are linked in some way.
- GIS is used for buffering, a technique to indicate the sphere of influence of a given point.
- It is used to selecting a group of unrelated points on a theme matching a set of criteria. Such groups are called clusters.
- It is used for location analysis. Location analysis is used to identify a location for a new retail outlet.

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Scope and Application Areas of GIS

1. Facilities Management (large scale and precise maps and network analysis are used)

- Locating underground pipes and cables
- Planning facility maintenance
- Telecommunication network services
- Energy use tracking and planning

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2. Environment and Natural Resources Management (Medium or small scale maps and overlay techniques in combination with aerial photographs and satellite images are used)

- Suitable study for agricultural cropping
- Management of forests, agricultural lands, water resources, etc
- Environmental impact analysis
- Disaster management and mitigation
- Waste facility site location

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3. Street Network (Large or medium scale maps and spatial analysis are used)

- Car navigation
- Locating houses and streets
- Site selection
- Transportation planning

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4. Planning and Engineering (Large and medium scale maps and engineering models are used)

- Urban planning
- Regional planning
- Route location of highways
- Development of public facilities

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5. Land Information System (Large scale cadastre maps or land parcel maps and spatial analysis are used)

- Cadastre administration
- Taxation
- Zoning of land use
- Land acquisition

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Functional components of GIS

Building Blocks of GIS

- A working GIS integrates five major components. They are as follows:
1. Hardware
2. Software
3. Data
4. People
5. Method

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Hardware:

- It refers to the computer in which GIS will operate.
- It includes devices ranging from centralized computer servers to standalone desktop computers.

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Software:

- GIS software provides the necessary tools and functions needed to perform various GIS operations such as storing, analyzing and representing the geographic data.
- The components of the GIS software are as follows:
1. Tools for input and manipulation of geographic information
2. Database management system
3. Tools for geographic query, analysis and visualization
4. Graphical user interface to access available tools

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Data:

- Data is the most important component of GIS.
- The geographic data are collected from various sources such as in-house collection or purchase from data providers.
- GIS is responsible to integrate the spatial data with other data as per the necessity of the application.
- Database management system is used to store, organize and manage spatial data.

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People:

- The people involved in GIS technology can be classified as developers and users.
- Developers are responsible to develop plans and implement the plans so as to apply spatial data to the real world problems.
- Users are responsible to use the technology so as to make their daily life better.

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Methods:

- Each GIS application has its own functionality.
- Each GIS is designed as per the predefined plan and business rules, which are the models or methods of the GIS, which are unique to each organization.

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Importance of GPS and remote sensing data in GIS

Role of GPS

- GPS stands for Global Positioning System.
- It is the satellite based technology that is used to collect the geographic information about the Earth.
- GPS technology is used in data collection phase of Geographic Information System.
- GPS helps to collect data about the position of the objects in the spatial space.
- It helps to provide the spatial data, which is the most important part of the GIS.
- Proper integration of GPS and GIS helps in inexpensive method of spatial data collection, that is further processed and analyzed by GIS for providing valuable geographic information.

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Role of Remote Sensing

- Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object.
- It makes use of satellite or aircraft-based sensor technology.
- It helps to collect data by detecting and classifying the objects on Earth.
- It is based on signal emission and reflection.
- Remote sensing is called active if a signal emitted by a satellite or sensor and the object reflects it, which is again detected by the sensor.
- Remote sensing is called passive if a sensor detects the reflection of sunlight from the object.
- It makes possibility of collecting spatial data of dangerous and inaccessible areas.