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Lab 5 Thematic mapping

# Lab 5 Thematic mapping - 44:005 Foundations of GIS Lab 5...

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44:005 Foundations of GIS Lab 5: Thematic Mapping In this lab, you will explore two other ways to display quantities on a thematic map using dot density and charts . In the second part of the lab you will learn how to perform a spatial join. Overview of the exercise… Dot density mapping Mapping with charts Choropleth mapping Pie chart, prism and globe maps in Google Earth. United Nations and Google Earth enthusiast Bjørn Sandvik has created a simple user interface that you can download and use to make thematic maps of UN data in Google Earth (www.thematicmapping.org). You can can download Google Earth 5.0 at earth.google.com. Foundations of GIS: Lab 5 pg 1 of 9

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Part I: Dot Density Maps A dot density map uses dots drawn inside polygons (counties, states, etc.) to represent the number of countable things like people, acres of corn, crime incidents, etc. in an area. The purple dots in this student’s map show the number of properties damaged by tornados in Oklahoma counties in 1999. The number of dots in the county is the important information, not the location ; Dots are randomly distributed within each county, so do not assume that the damaged property was located anywhere near the dot. http://www.personal.psu.edu/users/m/l/mlh382/index_files/483Project2Report.pdf Dots are characterized by a dot value and a dot size . Dot value refers to the number of occurrences that the dot represents. In the tornado map, each dot represents 6 damaged properties, so dot value = 6. If dot value was instead set to 10, there would be fewer dots needed on the map. Dot size, as the name implies, controls how large the dots appear. Using larger dots may give the impression that there are more occurrences, while using smaller dots may give the impression of fewer occurrences. Also, using large dots may cause overlap and make it hard to tell how many dots are in an area. 1. Open the attribute table for ‘IA_Census’ and read through the attributes available for mapping. In addition to total population, the dataset includes data on age, sex, ethnicity, families and houses. Which attributes would be interesting to show on a dot density map of Iowa? For this exercise you will create a dot density map to visualize population density of counties in Iowa using data from the US Census. 2. In the Symbology for the layer ‘IA_Census’, select Quantities Dot density .
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Lab 5 Thematic mapping - 44:005 Foundations of GIS Lab 5...

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