Geography 241
Lab 3 - Proportional Symbol Mapping/ TRI Data/ Google Earth

This lab will give you the opportunity to use the data we are working with for our final project that we have extracted from the TRI Explorer at the EPA.  At this point in the term we expect that you have developed enough functional capability to solve minor problems yourself as you work through this activity.  As always you may find this activity more palatable when working with a single partner.  There are 3 parts to this activity - it can be completed relatively easily in steps in the order as they are presented, each step is somewhat dependent on the previous one.  You should find the data set from Activity 1 useful as you complete this, and in fact you can't start the first part of this until you have the first part of the final project (presented in class) done.

Part 1 - Bringing the TRI Data into ArcGIS

This is a fairly simple process - you need to:

• In Excel save the TRI data you are preparing for the final project as a CSV file type (comma delimited).  Make sure before you do this to change all the column headings (field titles) to include only letters, numbers, or underscores (no spaces or other odd characters).
• In ArcGIS add the CSV file to your map (if you have forgotten to do the last part of the step above, go back and do this).
• Add the Census Tract layer for Cook County from the Lab 1 Data to your map.
• Create a geographic layer by using Tools-Add X Y Data...  You should see a dialogue that looks something like this:

• The system will normally sense that your fields "Longitude" and "Latitude" are X and Y respectively.  Use "Edit..." here to select a predefined coordinate system.  Select "Geographic Coordinate System" then "World" then use "WGS 1984".  Close this dialogue and you should see your TRI points mapped in the Census Tracts of Cook County.  If you haven't added this layer to your map you may see something different (why do you think this has happened?).

• Right click on this new layer in the Table of Contents and select Data - Export Data... to create a new shapefile from this layer.  Add this shapefile to your map after it is created.  At this point you should edit this shapefile and delete any features that do not appear to be inside Cook County (How can you do this? Think about it for a moment...)  Use this Layer for the rest of your operations in this activity.  Pay attention to where this is going as you will need it later, in..

Part 2 - Proportional Symbol Mapping With ArcGIS

Proportional symbol mapping is a form of mapping used in thematic cartography where we want to map quantitative (interval or ratio level) data at the occurrence of point symbols.  It can be a very powerful technique for certain types of data and there are many options in ArcGIS that allow both true Proportional mapping (where the symbol is exactly proportional to the quantity being mapped) and Graduated Symbols (where a limited number of classes are represented by range-graded symbols, similar to choropleth mapping).  We will use graduated symbols here.

• Using the shapefile you created above open the properties dialog to access the symbology tab.  Use Quantities - Graduated Symbols:

• The same general cautions about choropleth mapping from Activity 1 apply here.  Make  sure you understand what classification scheme you are using, and there are many controls that influence the graphical character of your symbols.
• Finish this part by producing a D-size thematic map of the Total On Site Releases for your TRI data.  Do your best to make this a strong and clear artifact  that communicates the geography of this phenomenon.

Part 3 - Exporting the Shapefile to Google Earth/ Working with Google Earth

This final part of the activity will show you how to become a producer of content that can be viewed using the geospatial browser from Google, known as Earth (catchy name).  It will also give you experience working with the Toolbox module, a powerful collection of routines embedded in ArcGIS.

• With your shapefile of the TRI data that you created in Part 1 open, open the Toolbox module.  This can be done with the Toolbox  button (if you don't see this add the Standard toolbar.  When open it presents a new panel of choices next to your map pane.  It should look something like this:

• Use the 3D Analyst Tools - Conversion - To KML to access the KML creation module.  You can double-click the Layer to KML selection to open a dialog for Layer to KML functions.  It looks something like this:

• You can also create a Thematic Version of this dataset by using the Map to KML selection and following these instructions in roughly the same sequence.  This works if you have saved a valid map (mxd) file.  This file then includes all open layers. 

• Select the TRI Layer and/or Map Document that you want to convert.  Name an Output File and make sure you know where it is going.  Set the Layer Output Scale to 1.  Click OK and this will create a KMZ file that you can then access with Google Earth.  Open the file in Google Earth and print a view of the file in an Earth window.

• You can find out lots more about Google Earth, KML, and the Google Earth Community through the DePaul Geography Google Mapping Page.

This activity is due November 4 at the end of class.  Turn in your completed graduated symbol map, D-size, and a Google Earth view, displayed in Google Earth and printed using the GISJet (the laser printer).  Make sure to save your KML file as you will want to use it later.  Feeling a little punchy after this one? Well... Aces!