FAQ: Frequently Asked Questions

This page should help answer many of the most frequently asked questions regarding GIS data and applications, with some specific information reagrding data provided on WAGDA by the UW Libraries Map Collection. It is written with UW users in mind, many of whom are using ArcGIS running on a Windows operating system. If you have any question that you don't see here, please let us know by sending an email to gis@lib.washington.edu.

A bit about the University of Washington network.
The Library is on its own subnet within the University of Washington computer network. So are independent departments such as Geography, Urban Planning, etc. Data that is stored on the "I" or "P" drive while working in the Geography lab is not available to you when working on computers in the Libraries, unless you make your own copy on a Flash Drive (or CD/DVD) and bring it with you to the lab.

ArcGIS 9.x

Q1: Who can use WAGDA data?

A: We provide data in two tiers: available to the public, and restricted by license agreement to UW students, faculty and staff to be used for non-commercial, educational purposes. If you are interested in acquiring some of the data that is restricted, email gis@lib.washington.edu, and we'll put you in contact with the data vendor.

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Q2: Where can I get/use ArcGIS software?

A: The UW has a site license with ESRI, the producer of ArcGIS and many other products. The site license requires that software be installed on University-owned computers AND be used only for educational purposes or non-profit reseach. This site provides information about how to get the software, how to install it, and how to connect with the GIS users at the UW.

 

Alternatives for current UW Students:

1. ESRI offers a free, one-year license to students enrolled in GIS courses at the UW. Software must be requested by the faculty member of the course and can be installed on student-owned computers.
2. Computer Labs at UW
• GIS Lab, Suzzallo Library, ground floor. Open 20 hours/week - hours posted on lab webpage.
• UW-Seattle department labs with GIS software to support students in their programs.
• UW-Seattle General Access Labs providing ArcGIS software.
• UW-Tacoma Campus Labs providing ArcView 9.1 software
3. Students may purchase ArcView and many of its extensions at an educational discount price (without the one-year time-out license) by calling ESRI TeleBusiness at 1-800-447-9778.
4. For basic GIS work you can download ESRI's free GIS viewer, ArcExplorer.
5. Free, open source alternatives to ArcGIS include GRASS and Map Windows and other applications. For advanced users who are familiar with the PostgreSQL relational database, try PostGIS, which adds support for geographic objects to databases.

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Q3: Where can I learn to use ESRI’s ArcGIS software?

A: Several resources are available, a few of which are restricted to UW students, faculty, and staff.

 

1) Getting to know ArcGIS Desktop, 2nd edition.
Book and data CD available for 3 day checkout from the Map Collection, Suzzallo Library, basement.  If you purchase this book it is accompanied by a demonstration copy of the ArcGIS software with a 180-day license. An online tutorial based on this text but designed to allow the user to bring in their own datasets is provided by the University of Arkansas Libraries.

 

2) ESRI Virtual Campus
Students, staff, and faculty at the UW may sign up for online, self-paced, no-cost training workshops provided by ESRI.

 

3) UW Courses

 a) Credit Courses at the University of Washington

Several academic departments offer courses that use GIS software to support research in their subject areas.

b) University of Washington Tacoma - GIS Certificate

Supplements degree programs in Urban Studies and Environmental Science.

c)  University of Washington Extension GIS Certificate Program,

A 3-quarter long program designed for working professionals.

 

4)  ArcExplorer is a free, simple to use GIS data viewer available for download at http://www.esri.com/software/arcexplorer/index.html
Although this has only limited functionality when compared with ArcGIS, it may be suitable for some projects or may provide some ideas about what GIS can do.

 

5) Mapping Our World: GIS Lessons for Educators, ArcGIS Edition
This book from ESRI Press is designed specifically for teachers to use in their classrooms, but may also be useful for others seeking to learn GIS software.  The full text of the book is available online in pdf format but when purchased the book is accompanied by an exercise data CD as well as a demonstration edition of the ArcGIS software with a one-year license.  In particular, see Module One: ArcMap Basics.

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Q4: Can you help me figure out what data I need for my project?

A: If you're just starting out with a GIS project use the Digital Geographic Data Needs Assessment to help you clarify your data needs. Staff in the Map Collection, Suzzallo Library can assist you with collecting and formating data for project use. Or email us at gis@lib.washington.edu

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Q5: How can I subscribe to the campus GIS mailing list?

A:  To subscribe to the campus GIS mailing list follow the instructions on this page http://mailman.u.washington.edu/mailman/listinfo/uw-gis-l.  For general information about mailing lists at the University of Washington visit the Mailman List website at: http://www.washington.edu/computing/mailman/. 

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Q6: Why do I get the ! next to my data layer?

A: When a data layer is added to ArcMap, the pathway where that data is stored is stored in the .mxd file. If you move the data layer to another folder, or move the .mxd file to another computer, the pathway to find and display the data will no longer be valid. To repair this:

1. Right-click the layer you want to fix and click Properties.
2. Click the Source tab.
   When a layer can't find its data source, you'll see information about the data it's looking for but no extent or coordinate system information.
   
3. Click Set Data Source.
4. Navigate to and click the layer's data source in the Browse dialog box, then click Add.
   The Source tab now shows the path to the data source, as well as its extent and the properties of its coordinate system.
   
5. Click OK.

To avoid this problem, save all your files using Relative Paths.

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Q7: How do I save my project to a CD/DVD/Thumb Drive/Dante, etc.?

A: If you set up your project to Save to Relative Paths you can move your projects to various computers using any storage media and avoid seeing the ! next to your data layers.

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Q8: How do I download or FTP my data from the Libraries' FTP site?

A: Using a web browser (Netscape, Internet Explorer, Mozilla, etc.)

1. Direct your web browser to http://www.lib.washington.edu/maps/gisfiles/. You can do this at a computer in your department, at home, in a lab, wherever is most convenient for you.
2. Navigate to the folder named after you to locate your data.
3. To download the file, right-click on the filename and select "save target as" or "save link as" (depending on whether you’re using Netscape or Internet Explorer).
4. A dialog box will pop up asking where you want to save the file. Put it on your disk, the computer’s hard drive, wherever you’ll be able to store it without fear of it being deleted

Q9: What types of files are provided on WAGDA?

A: There are many file types you will encounter when obtaining data from WAGDA and the University Libraries Map Collection. The following is a list of some of the more common file types you will encounter. Understanding file types will help you determine what format a file is in, and what software program the file is intended to be opened with.

• Standard File Formats
  Extensions are found after most file names (filename.***) and typically identify the type of file it is. Go to this Wikipedia article to learn more about file formats, including but not limited to GIS. This is an excellent resource for understanding what extensions are all about.

• Compressed files
  Typically during a download session you will run into compressed files having a *.zip, *.gzip, or *.tar extension. Compression allows us to save space, to transfer files more quickly, and to include multiple files in one downloaded file. For example, an ArcView shapefile consists of at least three files, *.shp, *.shx, *.dbf. "Zipping" these files together lets us bundle these files, rather than requiring you to download each file separately.
  
  You will need a copy of a decompression software such as WinZip for Windows installed on your machine to decompress files before you can view and manipulate them in a GIS. The program is available as free-ware and can be downloaded from here: http://www.download-zone-free.com/winzip/ if you do not have it loaded already.
  
  Once this file extraction program is installed on your machine you will then be able to extract compressed data into its original format. If you have problems running WinZip on your archived data it would be good to visit the WinZip information page at: http://www.winzip.com/info.htm.  

• ArcView Shapefiles 
  A Shapefile is an ArcView file format that can be used to create new themes from existing data. A shapefile has several component files, most commonly: *.shp, *.shx, and *.dbf. These files must be kept together to use the shapefile as a theme. 

• ArcGIS Personal Geodatabases 
  A personal geodatabase is a Microsoft Access database file *.mdb that can be directly accessed by ArcGIS. They can contain boundary files (known within the database as feature classes), imagery, and attribute data tables, and are a convenient format for organizing and keeping related geospatial and tabular datasets together. In addition, you can open the database in Microsoft Access and take advantage of the strengths of a relational database for organzing, aggregating, and summarizing data.

• Arc/INFO Export Files
  The Arc/Info coverages are comprised of many individual files into a "folder" structure. These can be exported into a more portable format. Large coverages will be converted to multiple volumes (i.e. *.e00, *.e01, ...*.e99). They can also be readily converted by other GIS formats, including MapInfo.

• Arc/INFO Coverages
  The Arc/INFO data model stores individual thematic map layers as coverages. A coverage is a directory consisting of several files.

• ArcView Project Files (discontinued in ArcView 8.x and higher)
  An ArcView project file (*.apr) saves the steps used in creating an ArcView session. A user can open an existing project file to quickly and easily display a series of related views and themes, as they were set up during the ArcView session. This file also keeps track of the queries made on the data and the extensions and scripts used for the project. You probably will not run into .apr files while at this web-site, but we may provide one to you after we prepare data at the library. 

• ASCII Files
  WAGDA files are sometimes stored in ASCII format. Check our help file for importing and reading DEMs stored as ASCII files.

Q10: What is an .e00 file?

A: An .e00 file is an Arc/Info coverage converted in Arc/Info Export format. This is an Arc/Info coverage and it is associated "info" files compressed into one easily portable file. Procedures for importing the file back into a coverage have changed between ArcView 3.x, ArcView 8.x, and ArcView 9.x. Those working with ArcView 3.x should review the information below. Those working with ArcView 9.x can follow these directions, provided by the ArcView 9.x help:

"In ArcView GIS 3, several of the import and conversion tools were contained as menu options outside the application (for example the Import71 utility). At ArcView 9, you can find these tools in the ArcView 8x Tools toolbar in ArcCatalog. The toolbar can be added through the following steps:

1. Start the ArcCatalog application.
2. Click the View menu, point to Toolbars, and click ArcView 8x Tools."

There are several import tools available in ArcCatalog. For .e00 files begin with ArcView 8.x Tools Toolbar and select Import from Interchange

Once imported, you should have two folders, one that matches the filename and one called "info." You need both of these files for it to be readable by ArcView – don’t delete anything! You’re using an Arc/Info coverage, which ArcView can read, so keep everything around and in the same directory.

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Q11: What do I do with a file that has a .zip/.tgz/.gz extension?

A: This means the file(s) have been compressed to make them smaller, and perhaps to bundle them together so you only need to download one file. Each of these extensions (.tgz, .gz, .zip, etc.) indicates that a different kind of compression software was used. The Libraries GIS staff primarily uses WinZip to compress and decompress files (available for free from http://www.download-zone-free.com/winzip/). The latest version of this software handles .zip, .tgz, and .gz file extensions (among others). In most campus GIS labs, you should be able to simply double-click on the file, and WinZip will automatically launch. Click "Extract" to decompress your files; again, save them to a safe location.

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Q12: What do different file extensions mean?

When I unzip my file, I get a whole bunch of files: parcel.shp, parcel.shx, parcel.dbf, etc. There are many files with the same name, but different extensions -- what are these files for?

A: A theme in ArcMap is comprised of many separate files that work together. ArcMap needs all of these files to be able to add the theme into your project. Don’t delete anything! The three files you’ll always see are *.shp, *.shx, *.dbf.

ESRI lists examples of other ArcMap file extensions (document excerpted below):

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Q13: What does an Arc/Info coverage look like?

When I unzip my file, I get two folders labeled "parcel" and "info." What is this?

A: This is an Arc/Info coverage, which can be read by ArcExplorer, Arc/Info, ArcMap or ArcView. When a coverage is copied to your computer, two folders are created – one labeled with the name of the coverage, one labeled "info." If you add more Arc/Info coverages to the same directory on your computer, additional folders are created for each coverage, and additional information is stored in the one Info folder. The Info folder holds database information about the coverage, which is pointed to by files in the coverage folder. You cannot successfully move or delete Arc/Info coverages using ArcView because of this relationship – these kinds of operations must be completed from within Arc/Info. However, you can successfully view Arc/Info coverages in ArcView and ArcMap.

To open an Arc/Info coverage in ArcView:

1. Select "Add Theme."
2. Navigate to the directory containing the coverage you’d like to use.
3. Click once on the coverage folder; you’ll see a list of files contained within the coverage. Most frequently seen are polygon, arc, node, and annotation. Most often you’ll want to use polygon or arc; sometimes you’ll want annotation, which is an Arc/Info text layer associated with the polygons or arcs.
4. To add a layer from within this coverage, click on the layer you’d like to add (to add more than one layer at the same time, hold down the shift key and click on each layer to add).
5. Click "OK" – your themes are now added to your View

Q14: What kind of DOQs/DOQQs do you have, and how do I view them?

A: DOQ/DOQQs are a digital form of aerial photography. Check out our collection of digital aerial photography. If you are using ArcView 3.x we have a separate help page.

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Q15: Why don't my datasets line up?

The most common reason that datasets that do not overlay each other is that the files miss projection files or have incorrect projection files. Please read the document How to align layers in ArcMap to help you resolve the problem.

 

For a stronger understanding of the critical geospatial data concepts of projections, coordinate systems, and datums, work through this exercise created by Phil Hurvitz.

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Q16: Where can I find out about projections?

A: First of all, make sure you read and keep copies of metadata for each datafile you'll be using, to keep track of information such as projection, publication date, source, etc. Another resource that may help you determine the projection of your data is the Projection_checker. The Projection checker is a set of Washington State themes (boundary, hydro, and transportation) from USGS which are in geographic, State Plane (N & S, in feet), and UTM (Zone 10 in meters); NAD27 and NAD83. These set of data will allow you to quickly display basic themes to see if they spatially "match" the data for which you don't know the projection.

 

To troubleshoot a projection problem in ArcGIS, these practical resources may help.

 

To learn how to reproject your data, consult the Projections Toolset in the ArcGIS Desktop Help. If you'd like more detailed information on projections and selecting the appropriate type, talk to your instructor. If you're interested in learning more about different projections, check out Peter Dana's Guide to Map Projections.

 

For a stronger understanding of the critical geospatial data concepts of projections, coordinate systems, and datums, work through this exercise created by Phil Hurvitz.

 

There are also several useful books about map projections such as Map projections--a working manual (1987) published by the USGS; Understanding map projections (2000) from the ESRI Press; and Map projection transformation : principles and applications (2000). Search the subject term "Map Projection" in the UW Libraries Catalog for additional titles.

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Q17: How do the geospatial data concepts of Projection, Coordinate System, and Datum work together?

A: Being comfortable with and working effectively with these concepts is essential to avoid bogus analyses, incorrect data summaries, corrupted data, and confusion. Phil Hurvitz has created this Projection/Coordinate System/Datum Exercise to test or build your knowledge of these concepts.

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Q18: How can I extract one shape from a set of larger shapes?

If you want to select a small area from a dataset with a larger geographic extent, e.g. a few blocks within Seattle, a single county from the entire state of Washington, you can clip that area and any associated data layers much as you would use a cookie-cutter. One way to do this is described in Steps 1-3 of this pdf handout. Another option would be to go to the Selection menu and Select by Location, where you can select all features that have their center in, or are contained by, the features in the larger layer: i.e. all the census tracts within a particular county in Washington. Once you have made the selection, you can left-click on the layer that contains your features in the Table of Contents, and go to Data and Export, to export the selected features out as a new data set.

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Q19: What style/format should I use to cite digital cartographic data?

A: A good reference for citing digital cartographic data is the book, Cartographic Citations: A Style Guide by Suzanne M. Clark, Mary Lynette Larsgaard, and Cynthia M. Teague (American Library Association, 1992). An online source is Citing Geospatial Data Resources provided by the University of Waterloo Library. The UW Libraries provides links to additional citation guides for maps & cartographic materials. If you have any further questions on this subject please contact the Map Collection at gis@lib.washington.edu.

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Q20: What is the difference between ArcView, ArcMap, ArcGIS, ArcInfo, etc?

A:  Each of these applications are functional components of ESRI's geographic information systems software suite. Some of these names related to functional increments determined by license and other relate to software versioning. Check out the answer on the Environmental Systems Research Institute’s (ESRI) ArcView 8.x webpage: http://www.esri.com/software/arcgis/arcview/faqs.html. 

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Q21: Where can I find census data and layers, and how do I get them into GIS??

A:  To get census data into GIS, you need to obtain two pieces of information: the actual data, and the boundary files that you will join the data to in order to map it. There are many options for getting the data, which include: using the geodatabases WAGDA has created for Puget Sound and Washington, downloading data and boundaries from the Census Bureau's American Factfinder, downloading data and boundaries from ESRI's Census Watch, using the Geolytics data CDs in the UW library, or downloading historical census data and boundaries from the National Historical Geographic Information System. Each source has it's advantages and disadvantages in terms of ease of access, ease of use, use restrictions, available time series, and available level of geography. See the Census Source Table (pdf format)for a comparison of the different sources, the WAGDA Census page for links to access these resources, and the WAGDA Census Help page for guidance in using them. 

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Q23: Color Oversize Printing - What are the Options?

A: On the UW-Seattle campus there are several options for oversize color printing

 

Students may find the 36" wide plotter printers available in the computer labs in Mary Gates Hall and Odegaard Undergraduate Library to be most convenient. Users are strongly encouraged to talk with a lab staff person before printing. Printing large format color plots is not cheap! You'll want to make sure you've got everything setup correctly in your layout before making the plunge.

 

Another option is provided by UWPosters.com located in Health Sciences T-271. Submit orders online or in-person with payment options UW Budget, credit card (Visa, Mastercard), or personal check.

 

Q25: How do I map (geocode) addresses?

A:  In order to match addresses to a street network, you must set up an address locator service using the ArcCatalog prior to selecting the geocode option in ArcMap. The Address Locator is essentially a set of instructions that tells the GIS how the attribute table of a particular street network is constructed, so it can appropriately match addresses to that network. In order to set up the locator service, you will need to know how the street network table is constructed - does it contain just the street address, or are there zip codes (also called zones) as well? Does it differentiate between addresses on the left and right side of the street? Is the network in a shapefile or geodatabase format? Examining the file and viewing the associated metadata will help you answer these questions and set up the service. For more information, see the following resources:

• ArcGIS Desktop Help for Geocoding
• Three Standard Geocoding Methods - an article from Directions Magazine
• BatchGeocode.com - find address coordinates and batch process up to 5000 addresses a day at no cost. See these instructions for importing the matched addresses to ArcMap.

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Q26: How do I get data tables into Excel, and how can I map them?

A:  See the Import Tables into Excel page for instructions on importing text files and pdf tables into Excel. Beginning with ArcGIS 9.2, Excel spreadsheets can be directly added to ArcMap. For previous versions of ArcGIS, Excel spreadsheets must be saved in dbf format in order to be added to ArcMap. Data in the Excel or dbf file can be joined to a boundary file based on a common field, which allows the data to be mapped. For an example on how to join tables, see the tutorial for using the WAGDA Census geodatabases, which includes this step in figures 6 and 7. Using Excel spreadsheets (or the dbf format) for adding data to maps is best for small, isolated projects. If you are working with large datasets or are working on an extensive, long-term project, storing your data in a database like Access may be a better choice. 

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Q27: How do I get data tables into Access, and how can I map them?

A:  Microsoft Access files can serve as personal geodatabases, for organizing and storing tabular data and GIS layers. Data stored in these geodatabases can be directly added to ArcMap. See the How to Import Data into Microsoft Access tutorial (in pdf format) for importing Excel spreadsheets and other tables into Access, and the How to Import Shapefiles into Microsoft Access tutorial (pdf format) for importing shapefiles to Access. For examples on how to join tables within ArcMap, see the tutorial for using the WAGDA Census geodatabases, which includes this step in figures 6 and 7.  

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Q28: How do I concatenate (combine) cells in Excel? Can I also concatenate cells in Access??

A:  Sometimes it is necessary to combine data that is distributed across multiple columns into one column. This is particularly necessary if you want to join two tables, or a table and a boundary file, based on a common field, but the unique identifier is divided into several different columns. For example, FIPS codes in census data tables may be divided into different columns for each level of geography: state code, county code, tract code, etc. You can combine these different columns into one by concatenating them. See the tutorials for concatentating cells in Excel and concatenating cells in Access.  

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Q: I've downloaded some files from WAGDA. The files have the extension '.gz'. After extraction with WinZip, the files have the extension '.e00', which ArcView 3.x does not recognize. Do you have any information on how to convert these files into the typical .shp, .dbf, .shx file format for viewing in ArcView?

A: An .e00 file is an Arc/Info coverage converted in Arc/Info Export format. This is an Arc/Info coverage and it is associated "info" files compressed into one easily portable file. To import the file back into a coverage, go to the Start Menu -> Programs and find ArcView. In the list of available programs under ArcView is a program called "Import 71". Use this program to import the file (see steps below). Once imported, you should have two folders, one that matches the filename and one called "info." You need both of these files for it to be readable by ArcView – don’t delete anything! You’re using an Arc/Info coverage, which ArcView can read, so keep everything around and in the same directory.

Start Import 71:

1. Next to "Export Filename," click on "Browse." Navigate to the directory containing your file.e00. Select the file you want to import, and click "OK."
2. Next to "Output Data Source," type the name of the file without the .e00 extension (in this example, "file," without the quotes). This will import the file to the same directory that the *.e00 file is contained. If you want to move the file to a new location, click the "Browse" button, navigate to the new directory and click "OK."
3. Click "OK." Depending on the size of your file, it may take several minutes to import. When finished, a dialog box will pop up telling you "Import Complete!

You have now imported an Arc/Info coverage. If you are unfamiliar with this file format, see the ArcInfo coverage question above.

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Q: After opening a project file, why does ArcView sometimes ask where its .dbf and .shp (and other) files are located?

A: When saving a project in ArcView or ArcMap, an .apr (in ArcView) or .mxd (in ArcMap) file is saved to your computer’s hard drive. .apr and .mxd files are a kind of script, telling the program what files to open and where they are, what extensions to load, and how to display your view. When you move an .apr or .mxd file from its original directory, the program will no longer know where to find your data, and will prompt you for each file you’re using. If you think you’re going to be moving your project around a lot, you can save all your data and your project file using Relative Paths to CD/DVD/Thumb Drive/Dante; then, when you move to a new computer outside of your lab, everything you need is in one place.

 

NOTE: You cannot simply save your .apr or .mxd file to a disk without the associated data, bring the disk to the library, and have your project open. Everything used in the project is needed, including all themes, images, etc

Q: How do I import and view in ArcView grid files stored as standard ASCII files?

A: Check out our ASCII readme file.

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Q: How can I use ArcView 3.x to view DOQQs provided on WAGDA?

A: Review this information about the DOQ/DOQQ files and the associated scripts.

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