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GIS terms
• Thematic map • Choropleth • Latitude & Longitude • Projection • Layer • Shape file • Base map
Thematic Map
• A map with a theme • Usually shows landmarks so you know
where you are looking • Start with a base map, then add points,
symbols, and shapes to display a concept • This will probably be the type of map you
are interested in making
Symbol = information Location = geographic relationship
http://pokemonrusset.com/Info/Locations
What is this?
• A volcano • ice cream with flavor
chunks • Meteorite crater • Lunar surface • Mt. Kilimanjaro • Polar ice cap • child’s art project
Same location showing altitude instead of geologic formations
• A volcano • ice cream with flavor
chunks • Meteorite crater
• Lunar surface • Mt. Kilimanjaro • Polar ice cap • Son’s art project
Latitude & Longitude
• A coordinate system used to locate any surface point on a globe.
• Rotates with the globe. (not sun based)
• With the addition of altitude, any point on, in or near a planet can be located.
Latitude & Longitude
http://www.flickr.com/photos/smithsonian/2940640045/
Latitude & Longitude
• Latitude = “parallels” • Are parallel on a globe • Measure North and South
• Longitude = “meridians”
• Long lines go North and South • Measure East and West.
Prime Meridian
• Zero point for measuring longitude
• Passes through the Royal Observatory in London
http://en.wikipedia.org/wiki/File:Greenwich_observatory_laser.jpg
Projections
• The sphere often needs to be converted to a flat image.
• Imagine a light bulb inside the globe and continent’s shadows projected on the wall.
• All projections distort the sphere.
4 types of Layers
• Point (locations of cities) • Line (roads and rivers) • Polygon (shapes of states and counties) • Images (like background terrain)
Planning your own map
• Data • Shape files (to visually hold the data) • Base map (the background geography)
Data: What information do you want to analyze or display?
• What is your question or problem? • Define what you want to visualize. • What point do you want to make? • What types of data did you collect? People, things, activities • When is the data? What time period(s)?
Shape files: The map outlines of the data
• If the data is about states, then you need the shape of each of state.
• Choropleth (“many areas”) maps fill each shape with a different color to indicate information.
• Shape files are also called “Polygon files”
Base map: an informative background for the data
• Helps the user know where the data is located.
• Gives other useful information such as terrain, roads and place names.
Data sources
• http://www.library.illinois.edu/datagis/ lists many excellent resources
• http://www.icpsr.umich.edu/icpsrweb/ICPSR/access/index.jsp (ICPSR) for social science data
• http://factfinder2.census.gov for U. S. census data
Historic data sources
• https://www.nhgis.org/ National Historical Geographic Information System
• Collection of census data and shape files both current and historic
US Census data
• Census data: American FactFinder http://factfinder2.census.gov/faces/nav/jsf/pages/index.xhtml
• Alternative portal to census data:
DataFerrett http://dataferrett.census.gov
Other workshops in this series
• Library GIS 101 – An introduction to some of the ways people are using GIS. Examples of maps and GIS tools in action.
• Library GIS 103 – ArcGIS: Importing images and giving them locations, creating shape files, shading areas of proximity
For more help… • Scholarly Commons for one-on-one
consultation. http://www.library.illinois.edu/sc/
• ATLAS data services and GIS training http://www.atlas.illinois.edu/services/stats/workshops/registration/
• ArcGIS classes at U. of I.: ESE 379, GEOG 105, GEOG 379, LIS 490GIG, LIS 490GIL(online), NRES 454, UP 418, UP 519
• Links to numeric and spatial data http://www.library.illinois.edu/datagis/
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