Gpy 206.1
Computers and GIS in Geography
Fall 2002
1. This is demonstration lecture using ArcView. In this lecture we will see how ArcView buffers around points and how we can use the information isolated in these buffered zones.
2. Problem: You work for a shoe manufacturer that wishes to locate a warehouse in northwestern Europe to serve the large urban markets there. A preliminary analysis has determined that the five sites available to you are: Paris, London, Antwerp, Frankfurt and Amsterdam. Which is the best site to locate the warehouse based on the following criteria: you want to reach the maximum number of urban residents within 500 kms of the warehouse? Five hundred kilometres is overnight trucking distance from the warehouse.
3. Do the following:
· open countries.shp in the World folder
· set the scale at 1:20,000,000 and centre the view on western Europe
· open cities.shp in the World folder
· for each of the five cities, in turn,
· find the city. Label it in the view.
· using Theme Create Buffer draw a circle of 500 kms around the city.
· using Theme Select by Theme select all cities which fall within the 500 km buffer.
· Go to ThemeTable and open the attribute table associated with the cities found
· Promote the selected cities
· Click on the Population field and go to Field Statistics. Record the Sum of the population of the cities selected within that buffer
· after all cites have been analysed recommend to the “boss” what city you would recommend for the warehouse.
4. Bonus: What are other factors that will need to be considered in the site selection process?
This is also a demonstration of ArcView capabilities. It serves as an introduction to this week’s lab exercise assignment.
1. Often it is necessary to create your own data table of attributes. To do so requires you to define fields (columns) and enter records (rows). In order to begin to build a table, start in the Project window and click on Tables, and select New. In the New Table window designate where you want the table saved (which directory) and give the table a name. It will be saved as a .dbf file (dBase).
2. An empty dBase window will appear. It is in this window that you enter your data. Before you can do so, you must define fields and the type of data you will be putting into each field. There are four types of data you can enter:
· Number (integer or real i.e. with decimals)
· String (numbers and characters in combination)
· Boolean (logical statements – true/false, yes/no)
· Date (in the form YYYYMMDD – e.g. 20021112)
You must also designate the field’s width, i.e. the number of characters/numbers in the field.
3. To define fields go to Edit Add Fields. In the dialogue box that appears give the name, data type and width of the new field. Click OK. Repeat these steps until the all the fields have been created.
4. Now you can add records to your table. Go to Edit Add Record. Click on the Edit tool icon (the middle one in the three tools on the second row) and then click on the first blank cell in the table. Type in the value. Click tab to move to the next field in that row. When finished with a record click enter (return). Go to Edit Add Record (or Ctrl+A) to create a new row. Enter your data. Continue until all data have been entered. When you have finished entering all records choose Table Stop Editing. Save edits.
5. Geocoding is the process by which you add point locations defined by street address, or other address information, to your map. To geocode a table requires that you have open a georeferenced Theme in your view. This Theme will serve as the reference data in the geocoding operation. In essence, you geocode a field of addresses by searching for those same addresses in the reference Theme and assigning the location of those places to your unmapped table attributes.
6. In ArcView before you can start entering and geocoding your data, you need to prepare the View you want to add the data to and identify the Theme which will serve as the reference Theme. In order to use a reference Theme in geocoding, it must have a geocoding index, an index that ArcView builds to speed up the process of finding addresses in the Theme. Make active the Theme you wish to serve as the reference Theme. Go to Theme Properties Geocoding (icon in the Table of Contents), select the address style: “US Streets” and indicate the appropriate Field containing the StreetName. Click OK.
7. The Geocoding Process: Click on the View to make it active. Choose the appropriate reference Theme. Go to View Geocode Address. Fill in the dialogue box that appear:
· Reference theme: Choose the appropriate reference theme.
· Join Field: What field in the reference Theme has the address information? Choose this field.
· Using Address Style: US Streets
· Address field: What filed in the address table has the address information? Choose this field.
· Display field: What field has the information you want displayed as a label for the points you are geocoding? Choose this field.
· Alias Table: <none>
· Geocoded Theme: What do you want to name your newly created geocoded Theme and what directory do you want to save it in? Click on the open folder to the icon and enter the Theme name and directory.
· Geocoding Preferences: Click on it and set all three scales very low. Say 20.
ArcView allows you to do a Batch Match (Automatic) or Interactive Match (manual). Start with Batch. ArcView will try to find the most likely candidates in your reference theme. Interactive Match is a hands-on, step by step matching process, which you will probably have to go to when Batch match fails to match all addresses.