Geographic Information System G. I. S. Geographic Information System

What is GIS? The acronym GIS stands for geographic information system. GIS is a computerized mapping software. Geographic Information Systems is a computer- based tool that analyzes stores, manipulates and visualizes geographic information, usually in a map. GIS helps us to make better decisions using geography.

Components of GIS A working GIS integrates five key components: hardware, software, data, people, and methods. Hardware: Hardware is the computer on which a GIS operates. Today, GIS software runs on a wide range of hardware types, from centralized computer servers to desktop computers used in stand-alone or networked configurations. Software: GIS software provides the functions and tools needed to store, analyze, 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 visualization. A graphical user interface (GUI) for easy access to tools. Example: Arc View, Arc Desktop, Arc GIS, ERDAS, etc

Components of GIS Data: Possibly the most important component of a GIS is the data. Geographic data and related tabular data can be collected in-house or purchased from a commercial data provider. A GIS will integrate spatial data with other data resources and can even use a DBMS, used by most organizations to organize and maintain their data, to manage spatial data. People: 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.

How GIS works? It brings together information from multiple sources to do various types of work. It uses location reference system, such as lat/lon Different kinds of data in map form can be entered into a GIS and GIS converts this information into a digital information (digital Map). GIS stores information about world as a collection of thematic layers. Examples: for solving many real world problems from tracking delivery vehicles to record details of planning applications to modeling global atmospheric circulations.

Data acquisition techniques: Digitization: Digitization is a process of tracing paper maps on the top of a digitizing tablet to digital format. Scanning: it converts analogue into digital data. Remote Sensing: It is a technique of acquiring data without actually visiting the place. Attribute Data: Data base files for spatial data can be stores in a variety relational data base software packages on a PC. …Continued on next slide

GPS (Global Positioning System): It is owned and governed by US department defense. It consists of 21 active satellites and 3 spare satellite revolving around the earth in fixed orbits to gather information. GPS works 24 hours.

Spatial Data Formats The two primary types of spatial data are Vector and Raster data in GIS. Vector Data: Vector data is not made up of a grid of pixels. Instead, vector graphics are comprised of vertices and paths. The three basic symbol types for vector data are points, lines and polygons (areas). Raster Data: Raster data is made up of pixels (also referred to as grid cells). They are usually regularly-spaced and square but they don’t have to be. Rasters often look pixilated because each pixel has its own value or class.

Difference between Vector Data and Raster Data Vector data consists of coordinates. Vectors can scale objects up to the size of a billboard.  It has faster display. It can also store attributes. It less pleasing to the eye. Raster data works with pixels. But we don’t get that type of flexibility with raster data. It has slower display. It cannot store attribute. It is more pleasing to the eye.

Raster data Advantages Disadvantages Inefficient use of computer storage Errors in perimeter and shape Difficult network analysis Inefficient projection transformations Loss of information when using large cells, Less accurate (although interactive) maps. Simple data structure Easy and efficient overlaying Compatible with satellite imagery High spatial variability is efficiently represented Simple for own programming Same grid cells for several attributes.

Vector Data Advantages Disadvantages Compact data structure Efficient for network analysis Efficient projection transformation Accurate map output Complex data structure Difficult overlay operations High spatial variability is inefficiently represented Not compatible with satellite imagery

GIS do these kinds of things: GIS accept geographic input in the form of scanned-in and digitized map images. GIS rescale or otherwise manipulate geographic data for different purposes. GIS include a database manager, usually a relational database management system (RDBMS). GIS provide answers visually, usually as maps or graphs.

Why is GIS important? Government Business 80% of local government activities estimated to be geographically based. Plots, zoning, public works (streets, water supply, sewers), garbage collection, land ownership and valuation, public safety (fire and police). Natural resource management. Highways and transportation. Retail site selection & customer analysis. Logistics: vehicle tracking & routing. Natural resource exploration. Civil engineering and construction.

Why is GIS important? Research Military and defense Battlefield management. Satellite imagery interpretation. Hard Sciences: Geography, geology, botany, etc. Social Sciences: Anthropology, sociology, economics, political science. Humanities: History, criminology.

GIS in day to day Improved communication. Better geographic information recordkeeping. Better decision making about locations. Example selecting route, zoning, planning, natural resource extraction, etc. Architecture GIS Applications.

Conclusion: With the help of GIS we are able to make sophisticated maps. Data gathered is about specific place, verified by theoretical or applied means and analysis is rendered. GIS allows user to create, collect, analyze and visualize data in a integrated database for use in a wide array of displaces. The biggest shift is from silo data stores to a single data repository.

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