Geography 387 – Fall 2011 Lab 3 Working with Attribute Data Lab 3: Working with Attribute Data 1.0 Overview In this lab you will strengthen your ArcGIS skills from previous labs and begin to work with attribute data. The overall steps of this lab are: - Download GIS data from a public website - Read the metadata for the data - Define the correct projection for the data - Create a geodatabase - Import the data into that geodatabase. - Look at the attributes - Project the data - Select features with queries - Export selected features to the geodatabase - Add fields and calculate values for them - Create a map with classified color scheme (a choropleth or thematic map) - Create a graph based on the attribute dataGeography 387 – Fall 2011 Lab 3 Working with Attribute Data 2.0 Get the data Make a Lab 3 work folder in your workspace (on your USB drive or local drive). Then go to the following web site: http://nationalatlas.gov/Geography 387 – Fall 2011 Lab 3 Working with Attribute Data The webpage may look different than the screenshot above because the National Atlas is a dynamic site, which changes its "What's New" section regularly. Click on the "About" link below the search window at the top. Read through the description of the National Atlas and answer the following question. Question 1: (1) a. When was the first National Atlas published? b. Before this digital version of the National Atlas was released on the Internet, when was the last update to the National Atlas? You are now going to download a GIS layer from the National Atlas site. Click on the "Mapping Professionals" in the dark blue bar at the top right. Read the information about "Raw Data" and "Raw Data Documentation". Now answer the following question: Question 2: (2.5) a. What formats do Vector files come in? b. What format do geostatistical data (additional attributes) come in? c. What format do Raster image data come in? d. What standard was used to create the metadata? e. Does metadata come with the raw GIS data files? You are now ready to download the raw GIS data layer from this site. First click on "Raw Data" icon. You will see a list of chapters, such as: Agriculture, Biology, Boundaries, etc. These chapters are used to group raw data into sets. Go to the Boundaries chapter. Several GIS layers are available for download. Each layer occupies a row in the table. Locate the "County Boundaries, 2001" row in the table. Find the column that has the link to the download and right-click on the link to the compressed shapefile, select "Save link as..." and navigate to your Lab 3 folder and save the download file there. This will download the shapefile in a compressed (Gzip) format. Note: if the National Atlas server does not respond, then just click here to get the data archive. Question 3: (2) a. Beside "County Boundaries, 2001" name 3 other layers that you could download from the Boundaries theme. b. What is the compressed and decompressed size of the Boundaries, 2001 data?Geography 387 – Fall 2011 Lab 3 Working with Attribute Data 3.0 Setting up the data in Catalog Unzip the contents of the downloaded file archive to your Lab 3 folder with 7Zip. This is a 2-step process: You will have to uncompress the “.gz” file first, and then run 7Zip again to extract the files from the “.tar” file. Ask your TA for help if needed. In Windows File Explorer, navigate to the Lab 3 directory and look at the list of files – you should see th files that make up a shapefile. Open ArcMap and establish a folder connection to your Lab3 working folder. Use the Item Description to preview the geographic and table information for the countyp020 shapefile. Question 4: (2.5) a. Using Windows File Explorer, how many files were contained in the downloaded file archive? b. Using ArcMap, is there a defined projection or coordinate system associated with this shapefile? What evidence do you have for your answer? c. How many columns are there in the Shapefile’s attribute table? d. What does each feature (i.e., row) of this layer represent? e. How many features (i.e., rows) are there in the table? From the Catalog, in the Properties window of the shapefile, select the Field tab. You will see the names of all the fields (columns) in the shapefile's attribute table. Close the Properties window. You should have noticed in the Description tab that none of the description fields were filled in. The metadata for this shapefile is in a separate file that came with the raw data. You should see this file appear in the catalog tree with the shapefile, but with a icon. If you double-click on this file, it should open up as an ASCII text file in Notepad. Explore the metadata to answer the following questions: Question 5: (1) a. At what scale is this data intended to be used? b. What U.S. Geological Survey (USGS) digital product was used as the source of this layer?Geography 387 – Fall 2011 Lab 3 Working with Attribute Data Look for the metadata section entitled "Spatial_Reference_Information" and answer the following question: Question 6: (4) According to the metadata: a. What are the units of the data? b. Is the Shapefile in a Projected Coordinate System (PCS) or in Geographic Coordinate System (GCS)? c. What is the datum? d. What is the ellipsoid? The projection for this data needs to be defined. Using the information from Question 6, and your skills from Lab 2, you will proceed to define the projection. But first... You are not going to import the projection/coordinate system information from another feature. Instead, you will select a predefined coordinate system. Click on “Select” in the “XY Coordinate System” tab of the shapefile properties and navigate to the "North American" folder under projected or geographic coordinate system (whichever is appropriate…you have the necessary information to answer this). Now find a "North American Datum" (NAD) that matches your datum in Question 6c. There are various versions of this coordinate system available, use the ‘plain’ one. Apply this coordinate system. Think: are you applying a PCS or a GCS? This will create a ".prj” file for your Shapefile. You can see this file in Windows File Explorer. Be sure you can locate this in your working directory as this is one of the lab deliverables. For the last step of preparing the downloaded GIS data in Catalog, you will create a file geodatabase and load this shapefile into it. In