Geographic information system facts for kids
A Geographic Information System (often called GIS) is a special computer system. It uses computer hardware and software to store, manage, look at, change, and show information about places. Think of it as a super-smart map that can hold tons of data!
Most of this information is kept in a spatial database, which is like a digital filing cabinet for maps. But GIS is more than just computers. It also includes the people who use it, the steps they follow, and all the knowledge about how to work with geographic data.
The term "GIS" can also mean the whole industry and job field that deals with these systems. It's similar to geoinformatics. The study of GIS is often called GIScience, and it's a part of geography.
GIS is used in many different areas, like engineering, planning cities, managing transportation, insurance, and even business. Because of this, GIS and location intelligence (understanding where things are) are super important for services that use location, like mapping apps on your phone.
GIS helps us connect information that wasn't linked before, using location as the main way to organize everything. Locations on Earth can be recorded with their date, time, and coordinates (like longitude, latitude, and elevation). All these real-world locations can be connected to each other, helping us understand patterns and make new discoveries!
How Did GIS Start?
While modern digital GIS began in the 1960s, many ideas behind it are much older. People have been using maps to understand places for a long time.
One of the first times someone used spatial analysis (looking at patterns on a map) was in 1832. A French mapmaker named Charles Picquet made a map of Paris. It used different shades of color to show how many people died from cholera in different areas.
In 1854, a doctor named John Snow used maps to find the source of a cholera outbreak in London. He marked where each sick person lived and where the water pumps were. By seeing where the sick people were clustered, he found the contaminated water pump. This was a very early and successful use of maps to solve a real-world problem!
In the early 1900s, a process called photozincography allowed maps to be made in layers. For example, one layer for trees and another for water. This made it easier to draw and print maps. Even though this used layers, it wasn't a true GIS because there was no computer database linking the information.
Later, in 1959, Waldo Tobler wrote about using computers for mapping. As computers got better, more mapping programs appeared in the early 1960s.
The First Real GIS
In 1960, the world's first true working GIS was created in Canada by Dr. Roger Tomlinson. It was called the Canada Geographic Information System (CGIS). It helped store and analyze data about Canada's land, like soils, farming, and forests. This system helped plan how to use the land across the country.
CGIS was much better than just "computer mapping." It could store data, combine different map layers, measure distances, and convert paper maps into digital ones. Dr. Tomlinson is often called the "father of GIS" because of his work. CGIS was used until the 1990s and built a huge digital land database for Canada.
In 1964, Howard T. Fisher started a lab at Harvard University. This lab developed important ideas for handling spatial data and created early GIS software like SYMAP and GRID. These programs influenced later commercial GIS software, like Esri's ARC/INFO, which came out in 1983.
By the late 1970s and early 1980s, more GIS software companies started, like ESRI and Intergraph. They combined the ideas of separating map information from other data, and organizing data into databases.
In 1986, the first desktop GIS product, MIDAS, was released for personal computers. This helped move GIS from just research labs into businesses.
By the end of the 20th century, GIS became more common. People started sharing GIS data over the Internet. Now, many free and open-source GIS programs are available. A big trend in the 21st century is combining GIS with other internet technologies, like cloud computing and mobile computing (using GIS on your phone).
GIS Software: Tools for Mapping
A single geographic information system is like a specific setup of software and data for one purpose (e.g., a city's GIS for managing its roads). GIS software is the general program that many different GIS setups can use.
Since the late 1970s, many software programs have been made just for GIS. Esri's ArcGIS (including ArcGIS Pro) is very popular. Other examples include MapInfo Professional and free programs like QGIS and GRASS GIS. These programs let you enter, manage, analyze, and view geographic data on your computer.
Since the late 1990s, with the rise of the Internet, GIS has moved to servers. This means you can access GIS data and tools online without installing special software on your computer. This is called distributed GIS. This idea has grown with cloud computing, where GIS tools are available online, like ArcGIS Online. Using the Internet for GIS is called Internet GIS.
Another way GIS works is by adding map features to other software. For example, some databases can now store spatial data and perform map-related operations. Also, many programming libraries (like Leaflet) let programmers add GIS features to their own custom software, like web mapping sites or location-based services on smartphones.
Managing Geographic Data
The heart of any GIS is a database that holds information about real-world things, like roads, buildings, or mountains. This information includes their geometry (where they are and their shape) and their properties or attributes (like the name of a road or the height of a mountain). Gathering and managing this data often takes the most time and money in a GIS project.
What Kind of Geographic Data Does GIS Use?
GIS uses location as the main way to link all kinds of information. Just like a regular database can connect different tables using a common ID number, GIS can connect unrelated information using location.
Any information that can be placed in space (and often time) can be used in GIS. Locations on Earth can be recorded with dates, times, and coordinates (like longitude, latitude, and elevation). These coordinates can be linked to real physical places on Earth.
Because GIS can connect so many different types of information by location, it helps scientists discover new patterns and behaviors in the real world that they couldn't see before.
How Data is Modeled
GIS data represents things from the real world, like roads, land use, or trees. These can be thought of in two main ways:
- Discrete objects: Things that have clear boundaries, like a house or a road.
- Continuous fields: Things that vary smoothly across an area, like rainfall amounts or temperature.
Traditionally, GIS stores data in two main ways:
- Raster images: These are like digital photos made of tiny squares called pixels. Each pixel has a value, like a color or an elevation. Satellite images are often raster data.
- Vector graphics: These use points, lines, and polygons to represent features. A point could be a city, a line could be a river, and a polygon could be a lake.
A newer way to store data is using "point clouds." These combine 3D points with color information, creating a 3D color image. This makes GIS maps look more realistic!
Getting Data for GIS
Getting data into a GIS database involves several methods:
- Primary data capture: Measuring things directly in the field.
- Secondary data capture: Getting information from existing sources, like paper maps.
- Data transfer: Copying existing GIS data from other sources.
All these methods can take a lot of time and money.
Primary Data Capture: Collecting New Information
You can enter survey data directly into a GIS from digital tools. GPS devices can also collect locations that are then imported into GIS. Today, people use rugged computers or even smartphones in the field to collect and edit live data using wireless connections. This means they can make maps and do analysis right where they are working, making projects faster and more accurate.
Remote sensing is another important way to collect data. This uses sensors on platforms like airplanes or satellites. These sensors can be cameras, digital scanners, or lidar (which uses lasers). For example, small unmanned aerial vehicles (UAVs) or drones can quickly map large areas with great detail.
Most digital data today comes from looking at aerial photos. Special computer workstations let people draw features directly from digital photos, even in 3D. Satellite remote sensing also provides lots of spatial data, using different sensors to measure light or radio waves.
Secondary Data Capture: Using Existing Information
The most common way to create data is called digitization. This is where a paper map is turned into a digital one.
- Heads-up digitizing: This is common now. You trace geographic data directly on top of an aerial image on a computer screen.
- Heads-down digitizing: This is an older method. You use a special magnetic pen or mouse-like tool (called a puck) on a digitizing tablet to trace features from a paper map.
After data is entered, it often needs to be cleaned up to fix errors. For example, in a road network, lines must connect perfectly at intersections.
Map Projections and Accuracy
The Earth is round, but maps are flat! So, we use different mathematical models called projections to represent the Earth on a flat surface. Each model might give slightly different coordinates for the same spot.
More accurate models of the Earth are called datums. For example, the North American Datum of 1983 is used for measurements in the U.S. When you convert coordinates from one datum to another, you need a special transformation.
Data Quality: Is the Map Right?
No digital map can be a perfect copy of the real world. But it's important that GIS data is of high quality. This means the data should be close enough to reality so that the results of GIS analysis are correct. The needed quality depends on what the map will be used for.
Here are some important parts of data quality:
- Accuracy: How close a measurement is to the true value. For example, if a map says a building is at a certain spot, how close is that to its real location?
- Precision: How detailed or exact a measurement is. Saying a building is at "2.3 Main Street" is more precise than "on Main Street."
- Uncertainty: Knowing that there might be errors or imprecision in the data. It's hard to know exactly how much error, but we can estimate.
- Vagueness: When something's boundaries aren't clear in the real world. For example, where does a city's "downtown" truly end?
- Completeness: Does the data set include everything it's supposed to? If a map of roads is missing some streets, it's incomplete.
- Currency: How up-to-date the data is. For most GIS uses, newer data is better.
- Consistency: Do all the parts of the data set fit together correctly? For example, do all roads connect properly at intersections?
GIS accuracy depends on the original data and how it's put into the system. Surveyors using GPS can provide very accurate locations. High-quality digital maps, aerial images, and powerful computers are making GIS even better for society. However, older sources like paper maps might not be as accurate.
When creating a digital map database, paper maps are a main source, but aerial photos and satellite images are also used to collect data and identify features. The scale of a map (how zoomed in or out it is) is very important because it affects how much detail you can see.
Spatial Analysis: Asking Questions of Maps
Spatial analysis is a fast-growing area in GIS. It means using tools to look for patterns, relationships, and trends in geographic data. Many GIS software programs now include these tools.
Geoprocessing is a common GIS operation. It takes input data, performs an action on it, and creates new output data. For example, you could use geoprocessing to find all the houses within 1 mile of a school. Other common operations include combining map layers, selecting features, and converting data formats. Geoprocessing helps us understand information to make better decisions.
See also
In Spanish: Sistema de información geográfica para niños
