Monday, December 10, 2012

GIS For Beginners - An Absolutely Simple Introduction

GIS - short for Geographic Information Systems, can be a difficult topic to understand for many people. Though GIS is a complex system, the benefits and uses of GIS are readily applicable to the masses. This article tries to explain the basics of GIS, its nuances, benefits and practical uses for everyone.

What is GIS?

Think of maps on computer. That's a very simple way to start understanding GIS.

Let's break down the term Geographic Information System, to understand each part:

Geographic: a location. For example - your house, a city, a highway connecting two cities
Information: information about the location. For example - how many people in the house, name of the city, lanes in the a highway
System: that ties-in the above two

GIS is a unique because
  • It combines location and information about the location. Using GIS, you can not only see the 'place' but find out more information about the place. Putting this concept in a system - typically a computer software - gives the ability to analyze this information in a powerful way.
  • It gives the ability to see and analyze many 'layers' of information at once. Many types of data, can be layered and analyzed together. For example, to find a suitable site for a new business in a city, one would need these different layers: land parcels, roads, population, household income, etc.

Some common GIS terminology

Before we dive-in, there are a few terms which you may not be familiar with:
  • Spatial: relating to 'space' or 'location'
  • Geospatial: Relating to location on earth, commonly used term to describe many GIS data and analysis
  • GPS: Global Positioning System, a satellite based system that gives accurate location information anywhere on earth.

 

How does GIS work?

The GIS workflow consists of following steps:

  • Data Collection: To build any GIS, we need data. The data is collected, converted to a convenient format and stored for use in subsequent processes. Example: If you are building a GIS Emergency Response, one needs data on road networks in the city, location of hospitals/fire stations/police stations, addresses of residents etc. Various tools such as GPS devices, Aerial photos, Survey equipment etc. can be used for data collection
  • Display and Analysis: The stored data is displayed and analyzed as per requirement. The data is displayed on a computer screen and the operator gives commands to perform analysis. Example: To find the shortest route from a house to the nearest hospital, the operator analyzes using a route finding algorithm on the roads data and the resulting path is displayed on the computer screen. Many different types of data is displayed as different layers and they are analyzed together.
  • Sharing: The result of analysis needs to be shared with the decision maker for further action. Example: In emergency response, the shortest route found using analysis, can be shared with the ambulance driver in form of printed or verbal instruction.

 

GIS Data

Majority time and effort in GIS is spent on collecting, formatting and storing the source data. So it is important to understand the nature of the GIS data and collection methods.

Two broad categories of GIS data are:

  • Vector: In a GIS, real-world objects are represented using either points, lines or polygons. For example, a city government may store the location of garbage collection sites as points, roads as lines and property boundaries as polygons.
  • Raster: Raster data can be thought of as a photograph. Commonly used raster data is aerial photos, satellite images, scanned maps and digital elevation models. These 'pictures' can be called a GIS data source when they contain information about the location - which part of the real-world do they represent. Hence, the raster data formats allow for storing real world coordinates of each pixel in the data. For example, a planning agency may use aerial photographs for city planning.
All GIS data, contains two-types of information - location and information about the location. So vector data will have coordinates ( location ) and attributes ( information about the location ). Example: A point data for a garbage collection site will have Coordinates - latitude and longitude of earth and Attributes - zip code, pickup time etc.

 

Applications of GIS

  • Emergency Response: GIS helps locate where help is needed and finding the shortest route for the responders to get there
  • Utility: Power, Telecom, Oil and Gas companies use GIS to map and manage their networks.
    Urban Planning: Planners use GIS to monitor city growth and identify areas future development
  • Insurance services: Insurance companies can process claims much faster and accurately, if they have access to mapping data and geographical information. Buyers benefits from reduced premiums and faster settlements
  • Wildlife management: GPS tracking of animals to study their habitat and migration patterns. GIS helps identify in wildlife conservation and optimal use of resources
  • Healthcare: Using GIS one can identify a possible epidemic outbreak and take preventive measures. Officials use GIS for planning healthcare facilities that are accessible to more citizens.
  • Marketing: Helps business sell and direct their products to the right market using GIS datasets and analysis tools
  • Disaster relief: Remote Sensing, GIS and field GPS units can help locate victims and speed rescue efforts
  • Tourism: First thing you do when travelling to a new place is to buy a map, right? By using GIS and web-mapping services, tourism authorities, travel agents, hoteliers and others can provide accurate and relevant information to travellers
  • Finding local information: people can search for local information, places to eat, shop and visit. A GIS database enables searches like 'restaurant within 2 kms from here'
  • Getting directions: Almost everyone in the western world would have used a direction finding service. To find turn-by-turn directions to any place. These online mapping services are powered by GIS technology.
  • E-Governance: Land Information Systems, uses GIS to create and manage digital land records. Governments all over the world use it to manage the land parcel database. Citizens benefit by getting accurate, timely and easy access to property information.
  • Military/Defence: Remote sensing techniques have been used for decades for surveillance and reconnaisance.
  • Agriculture: Surveying soil conditions, analysing crop patterns and using GPS-enabled field instruments to better manage agriculture produce
  • Real Estate: Developers benefit from getting quantitative information on market needs and existing infrastructure. Agents use mapping services to help clients find the right property by applying location constraints ( near to school, within 15 minutes drive work work etc )
  • Transport / Delivery services: Using live GPS tracking and GIS tools, companies can manage their fleet efficiently.
  • Art: Artists can effectively combine spatial information and power of mapping to express emotions.
  • Archaeology: Using spatial analysis techniques and visual interpretation of aerial imagery, archaeologists can discover potential sites, and manage the excavations.
  • Hydrological Modeling: GIS adds spatial dimension to hydrological modelling and helps predict water levels in rivers/lakes, rain water runoff, ground water availability and better manage water levels.
  • and many more