ArcGIS 1

Before you begin

Outside of workshop: general GIS resources at MIT are available at http://libraries.mit.edu/gis.

1. You will need an MIT Geodata Repository Account before beginning this exercise
If you do not already have an account you can create one at: http://libraries.mit.edu/gis/data/repository.html

2. Open the windows command prompt

    1. type: attach –DT gis

navigate to T:\gis\workspace2\workshops\arcgis1_iap07 and copy the contents of the “arcgis1” folder to your f:\usertemp\arcgis1 (use the F drive in the MIT GIS lab, use the C drive in 37-312)

 

Introduction

This exercise is intended to introduce you to the basic use of ArcGIS 9.1, a large program with many extensions and many uses. In this workshop we will become familiar with the standard tools in ArcMap used for creating and navigating maps, and utilizing and analyzing the tabular information behind the maps. You will learn to:

  • Add data from the MIT geodata repository
  • Symbolize vector data
  • Automatically label data in the map
  • Find specific records of information and zoom directly to them
  • Select records that fall within the same geography as another – “spatial selection”
  • Subset data – export selected records to a new file
  • Select by attributes (records in a table)
  • Symbolize data by different fields in the attribute table – graduated colors and normalizing
  • Create a new field in the attribute table and calculate values in it
  • Join tabular data to a gis layer for display in the map
  • symbolize multiple fields from the attribute table simultaneously using bar columns for display
  • Use the layout view to create a finalized map and export it in different formats (tiff, jpg, pdf, ai, etc.)

 

Open ArcMap (start-> all programs -> arcgis-> arcmap)

You will be prompted on whether or not you want to open a new map project or an existing one. You should open a new map.

Starting out

What does the ArcGIS interface looks like? It looks like this, more or less:

All of the controls are dockable. That is, the tools panel, which has the pan and zoom tools, is free floating. You can anchor it to the top bar of the window, if you wish, which makes it easier to find.

What's on the interface, besides the pan and zoom tools? Some drawing tools (see the bottom of the window), some menus which give you access to customizing tools among other things, and some map management tools. We will use many of these in the course of this tutorial.

Add data from the MIT Geodata Repository to your project

  1. If the MIT Geodata tool is not displaying at the top of your ArcMap document, right click in the toolbar area and click MIT Geodata
  2. Use the MIT Geodata Tool to search for Boston data using the Basic Search
  3. Select the BRA Planning Districts layer and click add selected layer to the map
  4. scroll down and select the Land parcels, 2006 layer, click ‘view metadata’ to see the descriptive information in a web browser, then click ‘add selected layer to the map’
  5. scroll down and select the Open Space layer and click add selected layer to the map
  6. make the layers display or not display by putting a check mark in the box to the left of the layer name in the table of contents. Leave the parcel layer unchecked for now so that the next few steps will go more quickly.  If things are taking a while to refresh you can click the Esc key on your keyboard to stop the refresh.
  7. adjust which layer draws on top by adjusting the order in which they are displayed in the table of contents (click the layer name and drag it above or below the other layer)  You will want your open space layer on top so it won’t be covered by the BRA planning districts polygon
  8. Exit from the MIT Geodata Search Tool

 

Make the parks display as green

  1. click the polygon below the parks layer and change the color to green

 

Symbolize the planning layer by name and label the neighborhoods

  1. Right click the Boston planning layer (sde_data.us_ma_boston_g45plnng_2000) and choose properties
  2. Click the symbology tab
  3. Change the symbology to categories: unique values with the value field set to “Name”
  4. Click add all values
  5. Click apply
  6. Click the labels tab
  7. Click the ‘label features in this layer’ box
  8. Check that the label field text string is set to “Name”
  9. Click ok

 

Find Back Bay and zoom to it

  1. Click the binoculars on the main toolbar
  2. In the ‘find’ box type Back Bay
  3. In the ‘in’ box limit the search to sde_data.us_ma_boston_g45plnng_2000
  4. Click the ‘Find’ button
  5. right click the result of the Find and choose select feature (This will select the Back Bay polygon and turn the outline of it blue on your map.)
  6. Right click the result of the Find again and this time click ‘zoom to feature(s)’
  7. Once you are zoomed to Back Bay set the parcel file to display by checking the box to the left of the layer named sde_data.us_ma_boston_g47parcels_2006

 

 

Select by location - Select all the parcels within Back Bay

  1. In the main menu click select-> select by location
  2. You want to: Select features from sde_data.us_ma_boston_g47parcels_2006 that are contained by the features from sde_data.us_ma_boston_g45plnng_2000; use selected features
  3. Click apply

 

 

Export the Back Bay parcels to a new, smaller file

  1. Right click the file name sde_data.us_ma_boston_g47parcels_2006, select data-> export data

 

  1. Export the ‘selected features’, using ‘this layers source data’; output the shapefile to f:\usertemp\arcgis1\parcels.shp
  2. Click yes when asked if ‘you want to add the exported data to the map as a layer’

 

Use select by attributes to explore the parcels gross tax

  1. Rick click parcels and choose ‘open attribute table’
  2. Quickly look through the many fields in this file (you could look up the codes for fields like LU (Land Use) in the metadata.  The easiest way to find the metadata is through the MIT Geodata Search Tool)
  3. Right click the colum name “gross_tax” and select “statistics”
  4. What is the mean gross tax for all parcels in Back Bay?
  5. In the main menu at the top click Selection -> Select by Attributes
  6. Make sure the layer listed is parcels and the method selected is create a new selection
  7. Scroll down in the fields menu and double click “GROSS_TAX”
  8. In the dialog box ‘SELECT * FROM parcels WHERE:’ complete the query for all records where "GROSS_TAX" = 0
  9. click ok
  10. in the bottom of the table change the “Show:” option from “All” to “Selected” so you have fewer records to scroll through
  11. Explore other queries with gross_tax and the statistics button to find out: How many parcels in Back Bay have a gross tax of 0?  Who owns them? What is the smallest gross tax paid that is greater than zero?  Where is it? What is the greatest amount of gross tax paid in Back Bay?  What is the mean tax paid for all records with a gross tax greater than 0?

 

Symbolize according to total land value – graduated colors and normalizing

  1. Right click the layer parcels and choose properties
  2. Click the symbology tab
  3. Change the symbology to
    1. Quantitites: graduated colors
    2. Field value: FY2004_TOT
    3. Normalization: None (Normalizing is the same as using a different field in the denominator. You could normalize by gross area to get the cost per square foot.  In the next section we will create a new field with the cost per square foot, so the values will be permanently stored in the file.)
    4. Choose a color ramp that is clearly going from low to high
    5. Experiment with the number of classes and classification type and choose the one that seems best

4. Click ok

5. Right click the file name and click ‘save as layer file’ to save your symbology to a file. (When you save your symbology to a layer file you can re-apply the symbology after trying others and it also gives you the option to apply the same symbology to other files.)

 

Create a new field - calculate the cost per square foot

1.      Right click parcels and open the attribute table

2.      Click options -> add field

3.      Name your field ‘cost_sf’ (there is an 10 character limit on field names)

4.      Choose type: short integer

5.      Click ok

6.      In the main menu at the top click Selection -> Select by Attributes

7.      Make sure the layer listed is parcels and the method selected is create a new selection

8.      Scroll down in the fields menu and double click “GROSS_AREA”

9.      In the dialog box ‘SELECT * FROM parcels WHERE:’ complete the query for all records where "GROSS_AREA" > 0

10.  click ok

(Some of the Gross Area records have a zero value, which would cause an error message since you can’t divide by zero.  Selecting everything in Gross Area greater than zero will make the next calculation perform only on the selected records.)

11.  Scroll all the way to the right in your attribute table and choose calculate values

12.  Click yes to perform the calculation outside an edit session (you will learn more about edit sessions in ArcGIS2 when you learn to edit your shapefiles)

13.  Click [FY2004_TOT] / [GROSS_AREA]

14.  Click ok

15.  Click ok to the errors (you can’t divide by zero) then click cancel – it will compute the records where gross area is not equal to zero

16.  right click on cost_sf and choose sort descending to make the most expensive homes per square foot list at the top of your table

right click on cost_sf and choose statistics to look at the min, max, median, etc.

 

thematic mapping – explore cost per square foot

1.      right click parcels ->properties-> symbology

2.      change the number of classes from the default of 5 to 10

3.      click apply and look at the map

4.      click classify and change the classification method from the default of  “natural breaks (Jenks)” to equal interval

5.      click ok, then apply

6.      explore the other classification types and notice how they change the look of the map.

Natural breaks – intervals are broken out based on natural clusterings of data

Equal interval – The range of possible values is divided into equal-sized intervals. Because there are usually fewer endpoints at the extremes, the numbers of values are less in the extreme classes. This option is useful to highlight changes in the extremes. It is probably best applied to familiar data ranges such as percentages or temperature.

Quantile - The range of possible values is divided into unequal-sized intervals so that the number of values is the same in each class. Classes at the extremes and middle have the same number of values. Because the intervals are generally wider at the extremes, this option is useful to highlight changes in the middle values of the distribution.

Note: Map symbology can be used to alter the way people view and understand information, just like statistics.  It is important to understand what you want to express in your map and how to best symbolize your data.

 

 

 

Add data to ArcMap from a drive:

  1. Use the add data button  to add f:/usertemp/arcgis1/census_blocks.shp to your ArcMap document.  (If you are adding data from a drive you have never used before you may not see it listed. 
    You would use the “connect to folder” button    to add new drive letters or connect to a specific drive path for easier navigation.)
  2. Add f:/usertemp/arcgis1/cen2k_b_pop_age_gen.dbf to your ArcMap document.
    Notice that your Table of Contents changes when you add the .dbf (database) file. It has automatically switched from Display view to Source view, which organizes the datasets according to where they are located on your drives. Notice that the cen2k_b_pop_age_gen.dbf is there, but cannot be displayed on the map since it is only a data table and contains no spatial information. Switch back to the Display view by clicking on the Display tab at the bottom of the Table of Contents. Notice that the cen2k_b_pop_age_gen.dbf is no longer listed, since it not part of the map display. Still, it is now available for use.
  3. Right click census_blocks.shp to open the attribute table and explore the fields
  4. Right click cen2k_b_pop_age_gen.dbf to open the table and explore the fields

You came across a file of gender by age group in tabular form and a US Census 2000 block shapefile on the MASSGIS website (http://www.mass.gov/mgis/laylist.htm).  You decided to use these files to explore if the number of males and females is fairly equal between different Census blocks in Back Bay.  The MASSGIS website that we downloaded the file from (http://www.mass.gov/mgis/cen2000_blocks.htm) told us: “The following table, available in dBase format (.dbf), which provides detailed demographics information, may be joined to the Blocks shapefiles on the LOGRECNO item.” 

We know if we want a fuller set of variables to choose from the US Census we should use these other sources:

·        US Census Bureau: http://www.census.gov

o       American Factfinder search –

·        how to find data such as population and average income

·        Geolytics is a company that has repackaged US Census data and made it easier to map.  The MIT Libraries have an assortment of Geolytics disks, which can be found using Barton: http://libraries.mit.edu/barton and doing an advanced search where “publisher” = “Geolytics”.  All Geolytics disks in the MIT Libraries collection are available at the Rotch Library circulation desk and are set up to be used on the Census workstation in the GIS lab.

·        MIT Libraries Census guide: http://libraries.mit.edu/guides/types/census/ summarizes a lot of information - what's in the census, how it's broken down, how to map it, etc

·        MIT Libraries Social Science Data Services: http://libraries.mit.edu/guides/subjects/data/

 

Join tabular data to a shapefile

1.      Right click the name of the file you want to join the data TO (census_blocks.shp), select ‘joins and relates’ -> ‘join’

2.      Select ‘Join attributes from a table’

3.      select the “LOGRECNO” for “the field in this layer that the join will be based on”

4.      select the “cen2k_b_pop_age_gen” as ‘the table to join to this layer…’

5.      select “LOGRECNO” as ‘the field in the table to base the join on

6.      Click ok

7.      We will be asked if want to index the join field in order to improve performance.  Since our file does not have many records performance will not be noticeably increased, so click no.

8.      Open the census_blocks attribute table and notice the column names are now tablename.columnname A join matches exact record matches one-to-one, and is not permanent unless a new file is created by exporting.  Also the field names are too long to read in the symbology options with this naming format. 

9.      Export the joined file to a new file named f:\usertemp\arcgis1\block_demog.shp

Symbolizing multiple fields in a shapefile using bar columns

Change the symbology of block_demog.shp to ‘Charts – bar/column’
select pop_male and pop_fem for display and give each colors that will be easy to remember and distinguish from each other
Do most blocks have a fairly even number of males and females?

Add an aerial photo of Back Bay to your project

All files in a GIS must have location information associated with them. If they are not correctly defined or ArcGIS can’t read their projection information it will not be able to make them line up with other data layers from the same location  If a file is correctly defined one can skip the ArcCatalog step and just open it directly in ArcMap. You should typically find information about a file’s projection and coordinate system in it’s metadata.

  1. Open ArcCatalog (Start -> all programs -> Arcgis - > ArcCatalog)
  2. navigate to f:\usertemp\arcgis1\BackBay.tif
  3. right click the file and open its properties
  4. scroll down to the “Spatial Reference” if the value is undefined click ‘edit’
  5. Click on the box 'Select' in Spatial Reference Properties
  6. Click on Projected Coordinate Systems
  7. Click on UTM
  8. Click on WGS 1984
  9. Choose WGS 1984 UTM Zone 19N.prj
  10. Click Add, then OK, OK.
  11. drag BackBay.tif from ArcCatalog to ArcMap
  12. explore the neighborhoods from above!

 

Create a layout of your map ready for publishing

  1. On the main toolbar menu of ArcMap click View and change from your data view to a layout view
  2. Change your map from portrait to landscape (file-> page and print setup)
  3. Adjust the data frame (area in dotted blue lines) to fill most of the page (area in the light gray box) but leave room for your title, scale bar, etc
  4. On the main toolbar menu click insert - > title
  5. Type in a title
  6. Click the insert button again and this time choose legend
  7. include the appropriate layers you want on your final map in your legend
  8. click next until  you complete the legend dialog screens
  9. Arrange the legend on  your page so it fits with the map
  10. Click the insert button again and this time choose north arrow
  11. Choose one of the many options from the north arrow selection
  12. Right click in your toolbar area and turn on the ‘Data Frame Tools’
  13. Rotate your data frame so that the Charles River looks horizontal on your page
  14. Note that your north arrow automatically rotates as you rotate your data frame
  15. Click insert again and this time choose scale
  16. Choose one of the many scale bars
  17. Right click the scale bar and choose properties
  18. Click the scale and units tab in the scale line properties
  19. Set your division units to kilometers
  20. Click Insert - > Text and add your name, the date, and the sources for your data
  21. Click ok
  22. Change the scale of your map by zooming in or out or typing in a desired scale and notice the scale bar automatically updates

 

Export your map to a pdf file

  1. Click file -> export map
  2. Choose save as pdf
  3. Note: if you save as an AI (Adobe Illustrator) the layers will remain as separate editable layers in Illustrator.  If you save as jpg or tif you can adjust the resolution of the exported file.
  4. Open your map in Adobe Acrobat to see what it looks like.

 

Save your ArcMap Document

File –> save

path

Note: when you save an ArcMap document you are only saving a link to the layers in your project.  If you move your project to a new location you will need to move all the files linked to your project with it.  Each shapefile has multiple files associated together – and they need to stay together to work properly! 

By default, ArcMap stores the full path name to each layer in the ArcMap document. This means that if you move your files around, your path name will change and you will need to redirect ArcMap to the new file location for each folder of data. If you will be moving files around we recommend saving a virtual path to the data files in your project.

File -> Map Properties -> Data Source Options – Store relative path