ESALab FAQs

general

Q: What does the University of Michigan offer in terms of support for users of GIS?
The University Library's Numeric and Spatial Data Services (NSDS) offers a lab, assistance finding and using data, tutorials, and one-on-one and group instruction. It is open to all faculty, staff, and students. The Center for Statistical Consultation and Research (CSCAR) also offers Spatial / GIS user support along with help regarding campus-wide GIS software licensing and installation. In addition individual departments/schools sometimes have additional support for their communities e.g. the School of Natural Resources and Environemnt has the Environmental Spatial Analysis (ESA) Lab.
Q: What does the Environmental Spatial Analysis (ESA) Lab offer in terms of support?
The ESA Lab offers free consultation and workshops to the SNRE community and research affiliates on topics relating to GIS, GPS, remote sensing, and spatial analysis. The ESA Lab also offers hourly service and support for clients within SNRE and UofM and for clients outside of UofM. Contact the ESA Lab Manager for details.
Q: Does the Unversity of Michigan have a mechanism whereby people can easily share spatial data sets with others who might be interested in them?
Yes. The UM Library's searchable online Digital Spatial Data Catalog has links to a data repository; all are encouraged to submit data sets to it. These data sets might be ones you have created or modified or might be data sets you've found and would like others to know about. As with all community efforts it will work best if community members contribute! Contact spatial-data-access@umich.edu for assistance.

education

Q: What does the University of Michigan offer in terms of GIS and Remote Sensing education?
Please visit the ESA Lab's education page for more information on: GIS/RS courses offered through the School of Natural Resources and Environment (SNRE) and the University of Michigan; workshops offered through the ESA Lab, CSCAR and NSDS; and the graduate certificate program in Spatial Analysis.
Q: Is there a tutorial I could go through to get acquainted with GIS software?
Yes. Both ArcView and Arc/Info are distributed by ESRI. From their web page, click ESRI Virtual Campus, and from there navigate through the GIScience, GIS Technology, and GIS Applications courses. Most courses from the ESRI Virtual Campus are available at no cost to University of Michigan faculty, staff and students. See the "Online GIS Training" page hosted by CSCAR for a listing of courses available for free and for enrollment instructions. Also, an introductory ArcView tutorial and others are available from the University Library's Numeric and Spatial Data Services at http://www.lib.umich.edu/nsds/tutorials/index.html. Staff at NSDS can also provide assistance with the use of these tutorials. Contact them at nsds@umich.edu.

UNIX

Q: What is UNIX?
UNIX is a powerful and flexible operating system/computing environment. Once logged in, a prompt is displayed on the screen by a program (called a shell) that interprets each command line you type. It is command line based, so a small repository of commands is necessary to function in a UNIX environment. Visual Editor (vi) is the UNIX's command-driven text editor.
- UNIX command cheat sheet
- vi (Visual Editor) cheat sheet
Q: Where can I find some resources on using UNIX?
A good general UNIX tutorial, including file permissions, is located at http://www.its.caltech.edu/its/facilities/labsclusters/unix/unixtutorial.shtml.
A more thorough, but less user-friendly resource, is located at http://www.idiom.com/UNIXhelp1.3/Pages/.
Q: Are there UNIX machines available for use in the ESA Lab?
There are 2 unix machines (Pangaea and Thor) available for use by individuals working on ESA Lab affiliated projects. Contact the ESA Lab Manager for details regarding access.
Q: Why can't I find ARC commands on Atlas (or other UNIX machines in the ESALab)?
In each user's IFS directory, there are several UNIX preference files often referred to as 'dotfiles'. If these preference files are messed up, or don't exist (perhaps the user has never logged into a UNIX machine before) then the UNIX login won't work properly.
The following steps will update your dotfiles to a standard set:
1. Log into pangaea or thor
2. Type the following commands:

% source /usr/local/skel/std.cshrc

% redot

% (answer yes to the questions redot asks)
3. Close the current window
The next time you log into a UNIX machine you should be all set.

Q: How do I mount the SNRE Data server from the ESA Lab UNIX machines?
1. First obtain or verify that you have a SNRE Novell network "simple password" with the SNRE IT consultants.
2. Log into pangaea or thor.
3. If one does not already exist, create a directory for your username in the /var/mounts directory by typing:

% mkdir /var/mounts/username
4. Mount the SNRE data server by typing:

% cifsmount //snre5_w/group /var/mounts/username
and typing in your SNRE simple password when prompted.
5. Now directories normally found under the SNRE Novell network "P" drive will show up in the directory you created, e.g. /var/mounts/username/esa.
Note: This mount is semi-persistent. The next time you log into the same machine, first check to see if the "connection" is still open. If not, repeat step 4.

Q: How do I do a Windows "unzip" in UNIX?
If the file you want to unzip (uncompress) has the extension ".gz" or ".z" type "gunzip {file_name}" at the UNIX prompt. If it has ".zip" then type "unzip {file_name}" at the UNIX prompt. These commands are the UNIX equivalent of using Winzip on Windows.

GIS

TIP => Launch the HELP system as soon as you open any GIS package.
Q: Where can I acquire public data?
First check the UM Library's searchable online Digital Spatial Data Catalog. The State of Michigan maintains a MI Geographic Data Library. The Southeast Michigan Council of Governments (SEMCOG) is a regional planning partnership that offers GIS data for souhteast Michigan. Digital line graphs (DLGs) and Digital Elevation Models (DEMs) are available for the United States through the U.S. Geological Survey (USGS). The Geography Network is also a decent place to start.<
Q: What about projections? OR Why don't my files overlay properly?
All data you are working with in a project must have the same datum, projection, and coordinate system! A telltale sign that they do not is that data don't overlay as they should. So, the first step in organizing a project should be choosing a consistent datum, projection, and coordinate system for all your data layers. Check the on-line documentation for guidance with this.
From the Geographer's Craft web site: 'Map projections are attempts to portray the surface of the earth or a portion of the earth on a flat surface. Some distortions of conformality, distance, direction, scale, and area always result from this process. Some projections minimize distortions in some of these properties at the expense of maximizing errors in others. Some projections are attempts to only moderately distort all of these properties.' This site has a lot of information on projections, as well as the closely associated topic of coordinate systems.

ArcView-specific stuff
Q: Why am I having trouble opening an ArcView project on a different machine? OR Why can't ArcView find the files in my project?
The ArcView project file (.apr) stores the entire path to the locations of files used in that project including the drive letter. Therefore, if you move to a machine with different drive nomenclature, ArcView looks in the wrong place for your files. A quick fix for this is to launch a simple text editor (Notepad is good for this) and do a global search and replace of the path in the .apr file. For example, you may need to change each instance of "J:/gis6/johndoe/coolproject" to "I:/johndoe/coolproject." If you don't know the path name, just scroll down in the .apr file until you see it.
Q: How do I create a point file from x,y coordinates stored in a spreadsheet?
Put the latitude and longitude coordinates in decimal degrees if they are not already. In Microsoft Excel (or another spreadsheet program), save the file in dbase format (DBF4), making sure that the cells are formatted to "number." To import into ArcView, click table => add and navigate to the dbase file. Then click on view => add event theme and specify "x & y" in the dialog box.
Q: Why can't I print from ArcView?
It is possible that your IFS space is full and it is causing problems for ArcView. To check this in Windows, navigate to your IFS directory through "My Computer," and when it is visible right click on the directory then click again on Properties. On a UNIX machine, type "fs listquota ~/" ("fs" means file system and "~/" represents your home directory); this will return stats on the percent of your IFS space being used.
Arc/Info-specific stuff
TIP => The first step each time you launch Arc/Info should be connecting to a workspace.
A workspace is a directory containing geographic data sets and the associated INFO files for use with Arc/Info. Connecting to a workspace tells the program where to look for the INFO files and update the geographic data. Follow these steps to connect to a working directory in workstation Arc/Info:
* launch ArcCatalog
* click the right-pointing arrow
* navigate to the appropriate directory on the left
Q: What is an arc interchange file (.e00)?
Arc/Info interchange files (.e00) have become the de facto standard format for the transport of Arc/Info files. Because "coverages" are are actually bundles of files, Arc interchange files are used to transfer coverages, INFO data files, text files such as AML macros, and other Arc/Info files between various machines as a single entity with all the files included. Arc interchange files can easily be converted back to coverages in Arc/Info by launching ArcToolbox then navigating to Conversion Tools => Import to Coverage => Import from Interchange File and entering the approrpiate file.
Q: I'd like to use the digitizer- how do I enable it in ArcInfo?
The digitizing table is accessible from only one machine in the ESA Lab (Mars). To establish a connection with the table and the puck for data input, the following command must be entered verbatim at the ArcInfo command prompt prior to digitizing:
digitizer gtco16 com1:9600:8bit:none

remote sensing

Q: What remote sensing software does the ESALab have?
Remote sensing software has considerably more capability for working with raster data files than do GIS software packages. If you are working with images consider using one or more of the following software packages: ERDAS Imagine 8.6 Professional (only available to the SNRE ESA Lab), PCI Geomatica 8.0 (available to install campus-wide, see http://gis.umich.edu), and Idrisi 32 (available to install campus-wide, see http://gis.umich.edu).
TIP: The vector module in ERDAS Imagine is the same as the ARC/INFO vector module, so ARC/INFO vector files are compatible with ERDAS Imagine. NOTE: Workshops are held for the SNRE community that give a brief introduction to ERDAS Imagine. Also, Remote Sensing of the Environment (NRE 441) is a good introductory course in remote sensing using ERDAS Imagine software.
Q: Is there an affordable remote sensing software package?
Yes, Idrisi has an education package that is reasonably priced. The program functions much like ERDAS Imagine and is similar in terms of capabilities.
Q: Where can I acquire public data?
Following are some good resources for public remote sensing data:
Michigan air photos => MI Geographic Data Library
U.S. air photos (high altitude; relatively inexpensive) => U.S. Geological Survey (USGS)
satellite imagery => Landsat 7 imagery
NOTE: Landsat 7 data cost approximately $600 per scene and some planning is required to acquire the appropriate scene at the right time, depending on your study needs. Prices vary for older Landsat data; these can be found using the EarthExplorer or searching the University of Maryland Global Land Cover Facility's (GLCF) database. The GLCF has some data available for approximately $380 + shipping and also maintains a library of Landsat scenes available for free download.
Q: What is HDF format and how do I import an HDF-format file into Erdas Imagine?
HDF is a physical file format that allows storage of many different types of scientific data, including images, multidimensional data arrays, record oriented data, and point data. Follow this link to a step-by-step guide on HDF data import (e.g., Landsat ETM+). Note: Always check the most recent version of the software you are using, because software updates often include support for new file formats.

other technology Qs

Q: How do I access and install spatial analysis software?
The spatial analysis software packages available for installation reside on the Center for Statistical Consultation and Research (CSCAR) server. They operate a web site that details the procedure.
Q: Where can I get more information on University of Michigan technology?
A good site for University of Michigan-specific information is operated by the university Information Technology Division (ITD).
Q: How do I restore a file that was on the SNRE network and was accidentally deleted or corrupted?
Depending on how long ago the file was there, the SNRE IT consultants may be able to help you. Go to http://www.snre.umich.edu/help and look under "Network Services | Data backups and restorations" for more info.
Q: What options exist for accessing the SNRE network data server?
Go to http://www.snre.umich.edu/help and click on "Accessing files on SNRE5" for details. Also see the question regarding mounting the SNRE data server under UNIX above.