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Chapter:
1. COMPONENTS OF GIS:
GEOGRAPHIC INFORMATION SYSTEM:
Geographic information system is an organised computer based information system which attempts to capture, store, manipulate, analyze and display both spatial and non-spatial data for solving problems such as problem related to research, planning, and management.
COMPONENTS OF GIS: [IOE-2076-BAISAKH][IOE-073-MAGH][IOE-071-MAGH][IOE-070-BHADRA]
Basically, GIS has following components:
Hardware,
Software,Â
Data,Â
Human andÂ
Method.
HARDWARE:
Hardware is the computer on which a GIS operates. GIS hardware has the ability to present images with high resolution and speed and to operate the database with large volumes of data quickly. GIS hardware consists of several parts to input data, process data, and print the results of the process.
SOFTWARE:
GIS software provides the functions and tools needed to store, analyse and display geographic information. Key software components are
Tools for the input and manipulation of geographic information.
A database management system (DBMS).
Tools that support geographic query, analysis and visualisation.
A graphical user interface (GUI) for easy access to tools.
DATA:
The most important component of a GIS is the data. Data may be:
Spatial Data
Spatial data is a real picture of an area located on the surface of the earth, generally represented in the form of graphs, maps, images with digital format and stored in the form of coordinates x, y (vector) or in the form image (raster) that has a certain value.
Non-Spatial Data (Attributes)
Non-spatial data is table-shaped data in which the table contains information possessed by the object in the spatial data. The data is in the form of tabular data that are integrated with existing spatial data.
HUMAN:
GIS technology is of limited value without the people who manage the system and develop plans for applying it to real world problems. GIS users range from technical specialists who design and maintain the system to those who use it to help them perform their everyday work.
METHODS:
A successful GIS operates according to a well-designed plan and business rules, which are the models and operating practices unique to each organization. The methods used in the GIS will be different for each problem. Good GIS depends on the aspect of the design and its real aspects.
How GIS Works??
A GIS stores information about the world as a collection of thematic layers that can be linked together by geography. This simple but extremely powerful and versatile concept has proven invaluable for solving many real-world problems from tracking delivery vehicles, to recording details of planning applications, to modeling global atmospheric circulation.
APPLICATION OF GIS IN CIVIL ENGINEERING: [IOE-2075 BHADRA][IOE-2076 BAISAKH][IOE 074-BHADRA][IOE-073-MAGH][IOE-071-MAGH]
GIS plays an important role in infrastructure development which is basically what civil engineering is all about.
Managing Visualizing and Integrating Data:
GIS can be used to interpret and combine data from many different formats. It allows you to integrate CAD drawings, satellite images, and parcel maps to produce a visual object overview and turn it into a clear, understandable report.Â
Transportation engineering:
Specifically, traffic engineering is boosted with the help of GIS. Once the database is created (It might take a lot of time and needs constant up gradation too) and network analysis is performed, it becomes immensely useful to predict the traffic conditions, finalise the optimum route, locate the nearest police stations, hospitals, find alternate routes, etc.
Infrastructure Management:
Having a clear and accurate picture of the project helps you to understand better your needs, minimize problems and mitigate environmental impacts and costs. All these procedures are improved when GIS is the primary system for data visualization and management.
Planning and site location
Environmental analysis
Infrastructure design
Construction management
Data collection and as-built surveying
Operations and maintenance
Critical Infrastructure Protection
The security and the safety of the building are in the hands of the engineers.Emergency managers use the enterprise GIS database to
â?¢ Identify critical infrastructure and hazards within affected areas.
â?¢Identify medical resources and route patients to nearest facilities.
â?¢Prepare evacuation routes for at-risk populations.
â?¢Provide accurate damage estimates.
â?¢ Identify priorities for short-term recovery needs.
â?¢Assess long-term recovery needs.
Urban Development and Town Planning:
The exceptional growth of urbanization in many countries such as Nepal, India has caused problems of sanitation, power and waste supply, housing, environmental pollutions and disposal of effluents. For a maintainable development of urban agglomeration, ideal resources development model and urban land use plan need to be generated by integrating the information on demographics, natural resources and socio-economic statistics in a GIS domain with the presently available satellite records.
Site Analysis:
GIS quickly analyzes various types of images and information for sites analysis. It's extremely accurate results presented geographically provide insights into interactions and connections as clients can relate easily to a simple map. T
Wastewater, storm water and Solid Waste Management:
Image interpretation can be used in a variety of ways to help monitor the quality, quantity of water resources.Remote sensing plays a vital role in delineating potential areas of groundwater occurrence for detailed exploration, thus reducing the cost and time involved in groundwater exploration.
ADVANTAGES OF GIS:
Traditionally, before the advent of GIS, engineering drawings and project plans containing informations are passed along from one engineer to the other, an engineer to his client or government agencies. Before you can get access to a particular data you would have to go through the stress of checking different places but with GIS authorized users can access data on a database from anywhere with ease.
GIS helps the engineer in saving money as the engineer no longer have to acquire tools to store data in hard copies and also building storage houses. All the engineer has to do now is to log in to a database.
GIS uses a geographic approach to everything. Every event on earth can be linked to geography because it involves locations, so if you know the particular location an event occurred , GIS can help you analyze the information you seek with conditions that you must have to identify the data and enter it into the GIS database.
GIS helps in better decision making regarding locations.
SUBSYSTEMS OF GIS: [IOE-2076 BAISAKH][IOE-073-MAGH][IOE-071-MAGH]
A GIS has four main functional subsystems. These are:
data input subsystem;
data storage and retrieval subsystem;
data manipulation and analysis subsystem; and
data output and display subsystem.
Data Input:
A data input subsystem allows the user to capture, collect, and transform spatial and thematic data into digital form. The data inputs are usually derived from a combination of hard copy maps, aerial photographs, remotely sensed images, reports, survey documents, etc.
Data Storage and Retrieval:
The data storage and retrieval subsystem organizes the data, spatial and attribute, in a form which permits it to be quickly retrieved by the user for analysis, and permits rapid and accurate updates to be made to the database. This component usually involves use of a database management system (DBMS) for maintaining attribute data. Spatial data is usually encoded and maintained in a proprietary file format.
Data Manipulation and Analysis:
The data manipulation and analysis subsystem allows the user to define and execute spatial and attribute procedures to generate derived information. This subsystem is commonly thought of as the heart of a GIS, and usually distinguishes it from other database information systems and computer-aided drafting (CAD) systems.
Data Output:
The data output subsystem allows the user to generate graphic displays, normally maps, and tabular reports representing derived information products.