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Monday, August 17, 2009

Introduction To Geographic Information Systems (GIS)

A geographic information system (GIS) integrates hardware, software, and data for capturing, managing, analyzing, and displaying all forms of geographically referenced information.
GIS software represents features on the earth, such as buildings, cities, roads, rivers, and states, on a computer. People use GIS to visualize, question, analyze, and understand this data about the world and human activity. Often, this data is viewed on a map, which provides an advantage over using spreadsheets or databases. Why? Because maps and spatial analysis can reveal patterns, point out problems, and show connections that may not be apparent in tables or text.
GIS uses layers, called "themes," to overlay different types of information, much as some static maps use mylar overlays to add tiers of information to a geographic background. Each theme represents a category of information, such as roads or forest cover. As with the old mylar maps, the layers which are underneath remain visible while additional themes are placed above.

A GIS is most often associated with a map. A map, however, is only one way you can work with geographic data in a GIS, and only one type of product generated by a GIS.
A GIS can be viewed in three ways:
- The Database View: A GIS is a unique kind of database of the world—a geographic database (geodatabase). It is an "Information System for Geography."
- The Map View: A GIS is a set of intelligent maps and other views that show features and feature relationships on the earth's surface.
- The Model View: A GIS is a set of information transformation tools that derive new geographic datasets from existing datasets.

Implementing GIS presents a unique set of challenges. Even the most well-funded projects can fail because of poor planning. 10-stage process for successfully deploying GIS are :
- Consider the strategic purpose.
- Plan for the planning.
- Determine technology requirements.
- Determine the end products.
- Define the system scope.
- Create a data design.
- Choose a data model.
- Determine system requirements.
- Analyze benefits and costs.
- Make an implementation plan.

Planners of all kinds—business analysts, city planners, environmental planners, and strategists from all organizations—create new patterns or reshape existing ones
every day.
1. Cartographic
- Irrigation
- Crop yield analysis
- Land evaluation
- Planning & Facilities management
- Landscape Studies
- Traffic pattern analysis
2. Digital Terrain Modeling
- Earth science resource studies
- Civil Engineering & military evaluation
- Soil surveys
- Air & Water pollution studies
- Flood control
- Water resource management
3. Geographic Objects Applications
- Car navigation systems
- Geographic market analysis
- Utility distribution & consumption
- Consumer product and services - economic analysis

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