Geography 387 – Fall 2011 Lab 7 Vector Spatial Analysis 1 Lab 7: Data Vector Spatial Analysis 1.0 Introduction This lab will introduce vector spatial analysis functions found in ArcMap. In particular, we will learn about selecting based on location, buffers, and overlay. We will use a variety of scenarios and datasets to illustrate these concepts. 2.0 Download data Before we begin, download the lab7.zip data archive into your Lab 7 folder on your USB thumb drive, or local computer C drive. Unzip the archive. You should have a lab7 folder with 4 sub-folders, one for each part of this lab. 3.0 Selecting nearby features When you analyze the relationships between map features, you might need to know which features are within a certain distance of other features (proximity) or share the same boundary (adjacency). The Scenario: Suppose you are interested in buying a gas station near Interstate 40 in Old Town, Albuquerque, New Mexico. One of your requirements is that it must be within 1,000 feet of the interstate so you can attract as many drivers as possible. Start ArcMap and open the map document lab7_part1.mxd in the lab7_part1 folder. When the map document opens, you will see a gas stations layer, a streets layer, a business layer, and a zoning layer. These are all geodatabase feature classes. Set the default geodatabase to the lab7_part1.gdb in the lab7_part1 folder from the File  Map Document Properties window, and make sure that the box is checked to “Store relative pathnames to datasources”. If needed, use the Full Extent button to zoom to and center the data in the map window. The I-40 freeway is selected (shown in light blue, also called cyan) in the streets layer. You will use this feature to select gas stations within 1,000 feet. See the screenshot below. Note: If you need to reselect the I-40 freeway features, use Select by Attributes from the streets layer Table Options, and select "STR" = 'I40' (there should be 30 selected features).Geography 387 – Fall 2011 Lab 7 Vector Spatial Analysis 2 Go to the Selection menu, Select by Location. The Select by Location tool lets you do simple GIS selection analysis. Keep in mind that the window provides a multitude of criteria that form a single “selection sentence.” I will provide you with the criteria for now, but later, you will have to try some of these criteria on your own. Enter the criteria as shown on the screenshot below:Geography 387 – Fall 2011 Lab 7 Vector Spatial Analysis 3 This tool will select features from gas stations that are within a distance of 1,000 feet of the selected streets. Read the criteria from top to bottom so that you understand the logic in this spatial query. Click OK when all your criteria are entered. Close the Select by Location window. Question 1: (4) a. How many gas stations were selected? Hint: Gas stations are point features and the selected set is in light blue (cyan). (2) b. What are the names of the selected gas stations? Hint: use the identify tool or look in the attribute table. (2) Unfortunately, neither of these two gas stations is for sale. You would like to make a tempting purchase offer, but first you must know the market potential for each station. Because you want to sell gasoline to business customers and employees as well as freeway travelers on I-40, you decide to find out which gas station is closer to more businesses. Go to the Selection menu, and scroll to Select by Location. Enter the selection criteria as shown on the screenshot below: Be sure to uncheck STATIONS in the Target layer part of the window. You want to select features from businesses that are within a distance of 1,320 feet (1/4 mile) from theGeography 387 – Fall 2011 Lab 7 Vector Spatial Analysis 4 selected features of gas stations. Notice that the check box next to "Use selected features" is checked, indicating that we are only going to consider the distance from selected gas stations (Stations). It tells you how many features are selected, although I blurred this out in the screen shot above. Also understand that I arbitrarily chose 1/4 of a mile as a buffer distance, but you could have put at 1 mile, 1 km, etc. by changing the buffer distance parameters. Note that the box next to “Apply a search distance” is checked. Click OK when all your criteria are entered as above. To see which business were selected and examine their attributes, open the Attribute Table for business. Notice that many of the businesses have the same address, indicating that they are located in a shopping center. Also note that your selected gas station points (from Question #1) also show up in the selection in the business layer. This is because the gas station layer was originally created by selecting gas stations from the business layer. For the question below, count the number of business points near each selected gas station by using the Identify tool . When you click on a highlighted business point with this tool, you will see in the results all of the businesses at that location. If you hold down the control key as you click on additional business points, they will be added to the existing list of businesses in the Identify window. You can then view the attributes for any of your business points by clicking it in the Identify window. Note: You can also identify multiple features with the Identify tool by holding down the left mouse button and drawing a box around the features that you want to identify. Select the business layer in the “Identify from:” drop-down box on the Identify window to use this option. ArcMap can also find features adjacent to selected features. To see how this works, consider a situation involving parcels of land. The Scenario: Suppose that Old Town is planning major improvements to its drainage system. Municipal planners need answers to these questions: 1) which parcels include or are adjacent to drainage ditches?; 2) how many of these parcels are in the city’s jurisdiction and how many in the county’s jurisdiction?; and, 3) what is the total acreage of parcels by jurisdiction? Turn off all the layers in the table of contents (TOC) and turn on the Zoning layer. Notice that drainage ditch polygons are already selected for you (cyan color). First, we’ll find out which parcels are adjacent to drainage ditches. Question 2: (4) a. Based on this selection of businesses, which of the gas stations you identified in Question #1