Geog
5190/6190 GIS
and Environmental Health
Important tips for working in the Lab
1. Store all your working data and projects on the D drive. Use the following folder to store your work: D:\GeogHealth\<your name>
If you want to backup and/or transfer your files to another GIS computer at home or in another lab, consider using an USB hard disk.
2. When creating new map projects, I suggest you set the ArcGIS to use "relative path names". This will save you from a lot of grief, if you frequently transfer your map projects to other computers. To do this, in ArcMap, select File-Map Properties, press "Data Source Options", and select "store relative path names", then OK out of the windows. Otherwise you may have to repair the links to all the data that you use if you move the project into a different folder.
3. Computers and software are crazy things. Save and backup often!
Lab 1: Introduction to ESRI ArcGIS
Goal: In this exercise, you will get a feel for creating maps with a GIS. You will learn about the components that make up the ArcGIS system. You will explore point, line, and area spatial data. You will map attributes associated with these spatial data. You will become familiar with the ArcGIS interface for zooming, panning, identify, and distance tools. You will explore the differences between classification schemes for choropleth maps. Learn how to use mapping symbols and labels. Finally, you will learn how to create a map layout, and export the map out to an image file for publication.
STEP 1
Download the following datasets to your computer (create a D:\GeogHealth\<your name> directory as suggested above in the tips):
All data in a zip
file [ at_tigeresri1125215847.zip ]
County Boundary [ cty0049035.zip]
Roads [ lkA49035.zip
]
Census Tracts, 2000 [ trt0049035.zip ]
Census Block Groups, 2000 [ grp0049035.zip ]
Census Blocks, 2000 [ blk0049035.zip ]
Census Block Group Demographics Data (SF1), 2000 [ sf1grp49000.zip ]
Census Tract Demographics Data (SF1), 2000 [ sf1trt49000.zip ]
Note that these are compressed zip files. You will need to uncompress them using the Winzip program. After uncompressing each zip file, you will end up with three files ending in .shp .dbf and .shx. These three files make up a single set of spatial data, known as an ESRI Arcview Shapefile. When you transfer Shapefiles, you want to make sure to transfer all three of the files.
When you uncompress each of the two Demographic SF1 files you will end up with only a single .dbf file. The dbf file is a table of census data that you will eventually "join" to the spatial data in the corresponding shapefile.
STEP 2
Start ArcGIS - ArcCatalog.
ArcCatalog is one of the three components within the ArcGIS system. Its purpose is to allow you to manage (or "catalog") your spatial data. It also manages metadata -- the descriptive documentation for each piece of data you use.
From the ArcCatalog menu, select File-Connect Folder. Select the directory where you stored the shapefiles you downloaded. By adding connections to folders you are telling the ArcGIS system where you store your spatial data. Notice that when you select the directory you have just added into the Catalog, instead of seeing the many .shp .dbf and .shx files, ArcCatalog simplifies things by just showing you the individual shapefiles. It is important to add connections to your data directories, otherwise you will not be able to use the data in a map project later.
If you right-click on a data item in the catalog, you get a context menu that allows you to copy and rename data, or view and set properties for the data. Notice on the right-hand window pane, there are tabs that allow you to preview the data and to view and edit metadata.
STEP 3
Start ArcGIS - ArcMap. You can do this from the Windows start button, or if you already have ArcCatalog running, you can select the menu item, Tools-ArcMap.
ArcMap is another one of the main components of ArcGIS. It is the main tool for making maps and analyzing your spatial data.
As soon as you launch ArcMap, it will ask you whether you want to create a new map or open an existing map. ArcMap creates mapping projects, which are files that end in the .mxd file extension. Maps are created basically by layering different spatial data on top of one another. These spatial data are not stored within the .mxd file, but rather the project simply points to data that resides in the catalog. This allows you to use the same data in a number of different mapping projects. Select "a new empty map", and OK.
IMPORTANT: Set up this project to use "relative path names". See Lab tip #2 above.
You are going to use the ArcMap interface a lot, so let us go through some of its features:
Your interface may look slightly different, since the various toolbars and windows can be moved around in ArcMap to suit individual preferences. But basically you should see something like the above interface. If particular toolbars or windows are missing, they may be turned off. To turn them back on, you can go to the View menu and click on the corresponding toolbar or window that is missing.
First, on the left-hand side there is Table of Contents window pane where you manage data layers and files. Note that there are two tabs on this pane. The Source tab shows us the files in use by the project. The Display tab shows us the ordering of the data layers used to visually construct the map (layers on top will cover layers underneath). The TOC window allows you to drag layers up and down to change the display ordering, and turn on/off layers. If you right click on a layer you get a context menu that allows you to manipulate individual properties of that spatial data layer.
Second, in the middle of the two windows is the Tools Toolbar. If you hover your mouse on top of one of the tools, you can see a description of what it does on the lower left status bar. There are tools for zooming in and out, panning the view, viewing the full extent of all your data layers, selecting and identifying data, and measuring distances.
Third, the large window pane on the right-hand side is the Display Area. This is where the map data is displayed. Notice that there are three little buttons at the bottom left of the Display Area. The first button that looks like a globe, puts you into "data view", which is where you manipulate your data and do spatial analyses. The second button that looks like a piece of paper, puts you into "layout view". You will want to go into layout view when it comes time to creating a nice publishable map with titles, legends, scale bar, etc. The third button is a "redraw" or "refresh" button that will force the map to redraw immediately if for some reason the drawing was interrupted by you changing the ordering of the layers, or some other manipulation.
Forth, note that Help is the right-most menu item. Good luck trying to find useful help though!
STEP 4
Let us add some data.
In the Display Area, first make sure we are in Data view by pressing the little globe in the lower left corner.
If you still have ArcCatalog open
you can simply drag and drop the data into ArcMap.
If not you can use the File-Add Data menu item in ArcMap
to add data from the catalog. Once you add the data, it should appear in
the display area, and a corresponding layer should show up in the Table of
Contents window. Add all the
Try changing the display ordering of the data in the TOC. Note that you have to be in the "Display" tab of the TOC in order to move layers up and down. How does the map change when you move data up and down?
Try turning particular layers on and off. Note how the map changes accordingly.
The cryptic names of the layers are a bit annoying, aren't they? Right-click on a layer to bring up the context menu, and select properties. In the properties of the layer, select the "General" tab, and change the name for the layer to something more sensible, the click OK.
Describe the census boundaries? What type of boundary is largest? What is the smallest?
STEP 5
We need to do a "Join" to relate SF1 demography data to the spatial boundaries displayed on screen.
A GIS is a relational database. Relational databases are nice because they rely on unique indices to relate data from one dataset to data in another dataset. For example, in this case we have a table of SF1 demography data (nothing spatial, just purely a table of data... you can try opening the dbf file in Excel if you do not believe me). However, in the SF1 files there is an index that denotes to which area the data corresponds. This same index is present in the corresponding shapefile. What we need to do is match up these indices, in other words, do a join on the index.
Note that if you added all the files to ArcMap in the previous step, you should see the two SF1 dbf files on the TOC in the Source tab. If not, add them now. Note though that they do not show up on the display tab of the TOC since they currently are not joined to any of the shapefiles.
Right-click on the census tract SF1 dbf file on the TOC and select "Open". A table will appear showing the contents of the data file. Note that there is a STFID column: this is the index we will use to join. Close the table.
Right-click on the census tract shapefile on the TOC and select "Open attribute table". A table appears showing the attribute data currently associated with the geography. Note there is the same STFID column. Close the table.
Let do the join. Right-click on the census tract shapefile on the TOC and select "Join". In the join window select "Join attributes from a table", 1. STFID, 2. the census tract SF1 demography table, and 3. STFID, then OK. That should do the join.
Now let us see what happened after the join. Right-click on the census tract shapefile on the TOC and select "Open attribute table". A table appears showing the attribute data currently associated with the geography. Note that all the demography data is now joined to the geography of the shapefile. Close the table.
Do the join for Census Block Group also using the same STFID index.
STEP 6
Lets play with the tools toolbar.
Use the +/- magnifying glass tools to zoom in and out. Note that you can drag a window to zoom into with you mouse. Also use the zoom center tools to see which way of zooming you like.
Use the "hand" pan tool.
Try the full extent tool. This zooms to the extent of all layers. However, you can zoom into a particular layer by right-clicking on an individual layer in the TOC, and selecting "zoom to layer" from the context menu. For this particular example there isn't much change since all layers cover roughly the same extent.
The select feature tool is very powerful. You change which layers are selectable from the "Selection" menu item and choosing "Set selectable layers". IMPORTANT: Generally, when you have selected items, any processing you subsequently do will only be applied to the selected data. For instance if you have selected a few census tracts, and then choose "Data-Export Data" from the layer's context menu, you can save just the selected tracts as a new shapefile. To unselect things, simple choose "Clear selected features" from the Selection menu. Note also that there are select by attribute and by location menu items that are also very powerful tools. Open the attribute table corresponding to data layer you are selecting. Note that when you select items graphically using the select feature tool, the same features are highlighted in the attribute table. Conversely if you select things in the table, they show up highlighted on the map. In the attribute table try the "All" and "Selected" buttons at the bottom of the table. If you wanted to export the selected attribute data, out to Excel for example, you could do so from Options-Export in the attribute table window. We will revisit Selection later on.
The regular select elements tool is used to move and resize drawing items on the map.
The identify tool allows you to see the attributes for
items you point to on the map. Note that you can select which layer's
attributes you are interested in seeing. Try changing the layer value to
see how attributes change when you point to the same location on the display
area. Can you locate
The find tool allows you to search attributes for a particular value. Use the find tool to search for "Foothill" in the roads layer. Right-click on the results to see what you can do.
The distance tool measures distance, of course. Note, to change the displayed distance units, you can right-click on the Display Area, select properties. From the properties window select the General tab, and change the display units.
With these tools, can you find out roughly how far the
STEP 7
Let us change the symbology of the data.
Symbology in ArcMap refers to how each layer is displayed (ie. the coloring scheme, size of symbols, thickness of lines, etc.).
One way of changing symbology is directly from the TOC. Click on the symbol displayed for each layer. A symbol selector window opens with a color palette for you to choose colors, and various other symbol properties.
Another way to change symbology is by right-click on the layer, selecting properties from the context menu. Then in the properties window go to the symbology tab to make changes.
Let us create a choropleth map. The census block group shapefile (you should have done the join with SF1 earlier) has a joined field called "Age Under 5", the population that is aged under 5, that we will map. Right-click on census block shapefile, and select properties. Under the symbology tab, select "Quantities" on the left since population is a quantity of information that we will map. We will use a graduated colors method to create a choropleth map. In the "Value" setting, select the "Age Under 5" field. Note that by default, the Jenks method with 5 classes is used to categorize the data. Click "apply". Try different numbers of classes, and try different classification methods using the "classify..." button to see how the legend and map changes with different settings.
Let us add some labels.
Right-click on the shapefile “Age under
Go back to the symbology tab in properties to try some alternative forms for mapping quantities, like using graduated symbols.
STEP 8
Let us create a layout for a publishable map.
To create a map for publication and have access to tools like north arrows, scale bars, etc. we must go into layout view. Press the layout button at the lower left of the display area (the middle button that looks like a piece of paper).
Note that once we go into layout view we get an additional Layout toolbar. This toolbar is for zooming in/out and panning the virtual piece of paper. If you want to change the scale of the map (in other words the zoom relative to the piece of paper) use the zoom tools on the regular tools toolbar. Similarly, this goes for the pan tools. Experiment with this.
From the insert menu add these elements: legend, title, scale bar, north arrow, and neatline.
Do a print preview from the file menu to check everything looks good.
Lets export the map to a jpg file. From the file menu select "export map", choose jpg format and save the map to your D:\GeogHealth\<your name> folder.
STEP 9
Email the jpg file to me with you and your lab partners' names.
Congratulations you are all done! Enjoy the weekend!