Geographic information system

A geographic information system (GIS) is a powerful tool that combines computer hardware and software to store, manage, analyze, edit, and visualize geographic data. Think of it as a map that can do much more than just show places — it can help us understand how different pieces of information connect to each other based on their locations.

GIS is used in many areas, from planning cities and managing forests to designing roads and studying wildlife. By using location as a key way to organize information, GIS helps people make smarter decisions. For example, it can show where emergency vehicles should go during a storm or how best to plant crops to grow more food.

The study of GIS is called GIScience, and it is part of the larger field of technical geography. This science helps us understand our world in new ways by looking at where things are and how they relate to each other. Whether we are looking at the spread of a disease, the path of a river, or the best route for a delivery truck, GIS provides valuable insights that help us solve real-world problems.

History and development

The idea of geographic information systems, or GIS, began in the mid-1960s when Roger Tomlinson first used the term. However, many ideas about geography and mapping that GIS uses today go back much further.

E. W. Gilbert's version (1958) of John Snow's 1855 map of the Soho cholera outbreak showing the clusters of cholera cases in the London epidemic of 1854

One early example of using maps to study health happened in 1832. A French cartographer named Charles Picquet made a map of Paris showing where cholera, a serious illness, was happening. He used colors to show how many people got sick in each area.

Later, in 1854, a doctor named John Snow used maps to find the source of a cholera outbreak in London. He marked where sick people lived and where water came from on a map. This helped him discover which water source was making people ill.

In the early 1960s, Roger Tomlinson created the first real GIS in Canada. This system helped organize information about land use, like soil types and forests, to help plan for the country's resources. Since then, GIS has grown to include many tools and ways to handle data, becoming important for many fields, from science to business.

GIS software

A geographic information system (GIS) can use special software to help work with maps and data about places. This software can be used by many different groups, like cities or companies. One popular example is Esri's ArcGIS, which includes tools like ArcGIS Pro and older versions such as ArcMap. Other programs include Autodesk, MapInfo Professional, and free options like QGIS, GRASS GIS, and MapGuide.

With the growth of the Internet, GIS tools can also be used online. This means people can access map data and tools through websites or apps without needing special software on their computers. Examples include ArcGIS Online and other online services. Some computer programs also have built-in map tools, helping them show and work with spatial data.

Geospatial data management

The core of a Geographic Information System (GIS) is a database that stores information about places, including where they are and what features or properties they have. This information can be kept in different ways, such as in files or special databases designed to handle spatial data.

Example of hardware for mapping (GPS and laser rangefinder) and data collection (rugged computer). The current trend for geographical information system (GIS) is that accurate mapping and data analysis are completed while in the field. Depicted hardware (field-map technology) is used mainly for forest inventories, monitoring and mapping.

GIS uses location as a key way to connect and organize many types of information. For example, it can link details about weather, population, or roads by their positions on the Earth. This helps people analyze patterns and make decisions using maps and other visual tools.

GIS can handle many kinds of data, like points (such as cities), lines (such as roads), and areas (such as forests). It also works with data collected from satellites, drones, and other tools, turning images and measurements into useful information about our world.

Main articles: Data model (GIS) and GIS file formats

Spatial analysis

Further information: Spatial analysis

GIS spatial analysis is a fast-changing field. GIS tools now commonly include analysis features either built-in, as extra tools, or through special add-ons. These tools help us understand patterns in data related to places. They can be provided by the software makers, or created by other groups or individuals.

Geoprocessing is a way to change spatial data in a GIS. It takes a set of data, does something to it, and gives a new set of data as a result. Common tasks include combining data sets, picking out certain features, and working with maps that show height and shape. Geoprocessing helps people make better decisions by organizing and studying spatial information.

Terrain analysis

Main article: Geomorphometry

Proximity analysis

Main article: Proximity analysis

Distance matters for many geographic questions. GIS offers many tools to study distance, like finding areas close to a certain point, measuring how far things are from each other, and planning routes through networks like roads.

Data analysis

GIS can help us understand patterns in data spread across areas. For example, by using maps, we can see how much rain falls in different places and use that to guess where water power might work best as a clean energy source.

Topological modeling

GIS can study how places relate to each other, like what areas touch or enclose others. This helps in modeling complex spatial problems.

Geometric networks

Main article: Transport network analysis

Geometric networks are lines connected at points, used to represent things like roads or utility lines. They help analyze how these networks work and are used in planning transportation, water systems, and more.

Cartographic modeling

Main article: Map algebra

Cartographic modeling is a way to combine and study different map layers. It lets us create new maps by following steps that process and analyze geographic data.

Map overlay

Main articles: Vector overlay and Map algebra

Putting several maps together can create a new map. For example, we can find where two areas overlap or combine their features into one map. This helps in understanding complex spatial relationships.

An example of use of layers in a GIS application. In this example, the forest-cover layer (light green) forms the bottom layer, with the topographic layer (contour lines) over it. Next up is a standing water layer (pond, lake) and then a flowing water layer (stream, river), followed by the boundary layer and finally the road layer on top. The order is very important to properly display the final result. Note that the ponds are layered under the streams, so that a stream line can be seen overlying one of the ponds.

Geostatistics

Main article: Geostatistics

Geostatistics studies how data changes across space. It helps predict values in areas where we don’t have direct measurements, using methods like interpolation to estimate missing information.

Address geocoding

Main article: Geocoding

Geocoding finds the exact location of addresses or other place names by turning them into coordinates on a map. For example, it can place a dot on a map for an address like 500 on a street that runs from 1 to 1,000.

Reverse geocoding

Main article: Reverse geocoding

Reverse geocoding does the opposite: it takes a set of coordinates and estimates the address that might be there. For instance, clicking on a point in the middle of a street might give an address close to number 50 if the street numbers run from 1 to 100.

Multi-criteria decision analysis

Main article: Multiple-criteria decision analysis

When combined with GIS, multi-criteria decision analysis helps people choose the best options from many possibilities. For example, it can help pick the best places for environmental restoration by weighing different factors like vegetation and nearby roads.

GIS data mining

GIS or spatial data mining applies data analysis techniques to geographic information. This can uncover hidden patterns, such as environmental changes, and help make better decisions. It often combines GIS with machine learning to study health and social issues across regions.

Data output and cartography

Main articles: Cartographic design and Digital mapping

Cartography is the art of making maps to show geographic data. Today, most maps are made using computers and special software called geographic information systems (GIS). This software helps users control how the maps look.

Cartography has two main purposes. First, it creates maps and graphics to help people understand data and make decisions. Maps can be shown on screens or printed on paper, and some can even be viewed on the web using Web Map Servers.

Second, cartography can produce lists and other information for more analysis. For example, a list of all addresses near a certain location can be made.

Traditional maps show the shape of the land using lines or shaded areas. Modern GIS can combine different types of data to create 3D views. For example, elevation data can be combined with satellite images to show a 3D view of a place like San Mateo County, California.

Today, many people use web mapping services like Google Maps and Bing Maps, as well as OpenStreetMap. These services let anyone view and use geographic data. Some even let users create their own map applications. However, maps made without proper training might not follow good map-making rules and could be misleading.

Uses

Since the 1960s, geographic information systems (GIS) have been used in many different ways. GIS helps people understand where things are and how they relate to each other. This is useful for both studying the world and making decisions.

GIS can be used for scientific research, like learning why some places are better for certain businesses. It can also help with managing resources, such as deciding the best way to use land or plan city services. People use GIS in many areas, including economics, politics, transportation, education, archaeology, urban planning, public health, and national defense. It is also used to study nature, like geology, biology, and climate.

GIS tools are used by governments, businesses, non-profits, and even individuals with smartphones. They help with projects that last a short time or with long-term plans that continue for many years. Today, GIS is often part of bigger technology systems, making it easier to share information.

Other aspects

Main article: Open Geospatial Consortium

OGC standards help GIS tools communicate.

The Open Geospatial Consortium (OGC) is a group of companies, governments, and universities that work together to create rules for using geographic information. These rules help different computer programs work together to share maps and location data.

GIS can also help us study how the Earth changes over time. By using data from satellites, scientists can see how plants grow, how weather patterns shift, and even how people move during the day. This helps us understand our planet better and plan for the future.

Societal implications

Main articles: Neogeography and Public participation GIS

GIS technology has many important uses in society. During the COVID-19 pandemic, GIS helped health agencies track and show how the disease spread, which was very useful for making decisions. GIS can also help people feel more trust in their government by making information easier to understand and share.

GIS is useful in many areas. In schools, it helps students learn about geography by using real maps and data. Local governments use GIS to manage many tasks, like planning where new businesses might go, keeping parks and trails safe, and tracking important city services. It is also important for protecting important historical places by helping watch over them and plan how to keep them safe.