2. Learn how to compress and uncompress data in UNIX.

3. Quick introduction to ArcInfo.

4. Import data from internet sources.

5. Import function on the pc
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1.  Creating a point coverage:

* Often data is collected in the field as a series of points. These points can represent anything from test sites for scientific studies to fire hydrants or customers homes.

* The geographic coordinates of the point can be taken and recorded with a GPS unit along with its attribute information.  Attributes are additional descriptive information about something.

* We have created a point data file. This data along with other data used for this lab must be copied to your directory. The directory is located in /home/gisclass and is called lab2.  The file we will use to create our point coverage is called waypoints.txt.

A.  Copy this directory to your own GIS account by accessing your UNIX command line interface in the terminal window:

* cp -r   /home/gisclass/lab2   /home/gis#/lab2.   (REMEMBER we use -r because we are dealing with a directory)

* replace the "#" above with your own GIS number.

* If you list out the contents of your account you should now see a sub directory called lab2.  If you list the contents of lab2 you will see the hopefully see the following:

counties.tar      fire.tif.Z        newspost.text.gz

C.  On the "Welcome to ArcView" window, click on "Open an existing project."  Open the existing project that we saved in last week's lab or the one you created on your own during the past week.

*It should contain Cache County boundary, roads, city limits, and a photo point file.

To get started we need to add the text file to our project so we can work with the data.

D.  The small sub window that initially opens when you start ArcView (As seen below) has several options: VIEWS, TABLES, CHARTS, LAYOUTS, and SCRIPTS. Choose "TABLES" and click "ADD".

E.  Browse for waypoint.txt (located in the lab2 directory) and add it to your project by double clicking the file.

* You should now see a spreadsheet style table. At the top of the columns there will be titles including Longitude and Latitude.

F.  In the menu bar located near the top of the ArcView window, select VIEW then ADD EVENT THEME.

* A small box will appear asking for:

    (1) Which table to use to create the point coverage

    (2) Which column from that table to use for the x-value (easting)

    (3) Which column to use for the y-value (northing).

G.  Choose the text file we just opened and the appropriate columns for the x and y values and then click OK.

* You will see a new theme appear in your view options. Select it to make it visible in your view. If all went correctly it should appear somewhere in Cache Valley.

Now we have a new theme crated from GPS points, nice, but we're missing something...  If you open the attribute table for this coverage (by clicking the table button in the button menu at the top of the screen) you will see that the only attributes we currently have are the site ID numbers and the longitude and latitude.  It would be nice to be able to add additional attributes such as a description of what each point is table. To do this we can:

1. Follow the above instructions for adding a .txt file add the file features.txt to our project.

* We are going to link two different tables together.  When joining tables, it is necessary for the tables that are being joined to share a common feature. With both tables open it is apparent that the site ID number is a common feature in both.

* Make sure that you do the next few steps in order, or your tables will be incorrectly joined.

2. In table features.txt select the site ID column by clicking on the top of the column.

3. Select the site ID column in waypoint.txt.

4. Go to TABLE in the menu and select JOIN.

*It's important to note that if the "clicking" isn't done in the correct order the join will be backwards.  If this happens, and it will, don't worry, go up to the 'table' pull-down window and choose Remove all Joins and then try it one more time...

* Now the two tables are one and each point knows not only where it is in the world, but also what it is.

RIGHT!

 
 

2.  Compressing and Uncompressing Data:

* Often, when working with very large files it is necessary to store them in a compressed format to save space. Additionally, most data found on the internet comes in a compressed format to make downloading easier. Here we will discuss three compression types commonly used.

* .GZ

A.  In your terminal window cd into your lab2 directory.

B.  Long list out the contents of the file (ls -l command).   Note the file size.

* You should see a file called newspost.gz

C.  At the prompt type: gunzip newspost.gz

* This will uncompress the file and remove the .gz extension.

*Using the long list command look at the size now...

*Using the more command look at the first few lines of the file.

D.  Now at the prompt type: gzip newspost.

* The file is now rezipped and much smaller than before.
 

* .Z

1. While in your lab2 directory list out the contents.

* You should see a file called fire.tif.Z

2. At the prompt type: uncompress fire.tif.Z

* This will uncompress the file and remove the .Z extension.

*Look at the files size, note the change

*We can look at this picture by typing xv fire.tif at the command prompt  (This pic is from Dr. Box)

3. Now at the prompt type: compress fire.tif

* The file is now rezipped and much smaller than before.
 
 

* .tar: This type of compression is a little different than the other two. A .tar is not really a compressed file. It is actually several files that are tied together and then given one file name.   This promotes easy transport of a number of files such as ArcView shapefiles or images with world files (we will discuss those in a few weeks).

1. While in your lab2 directory list out the contents.

* You should see a file called counties.tar

2. At the prompt type: tar xvf counties.tar

* If you list out there will be several files now named counties.shp, counties.shx, counties.dbf, counties.sbn, and counties.sbx.

* We will not go into how to tar files. We will mainly be working with files that we will want uncompressed and untarred.

*In ArcView open your project and add the theme counties from the lab2 directory.
 

Introduction to ArcInfo:

* ArcInfo is another GIS software package created by ESRI and is generally used as a higher level, more sophisticated GIS package.  This isn't saying it's better than ArcView (it is) but, um, well...together with ArcView are generally the industry standards. ArcInfo and ArcView do several of the same operations with GIS data. ArcView is a graphic user interface (GUI) based program where the user points and clicks for the desired operations. ArcInfo is a command line driven program (much like the UNIX environment) requiring the input of text by the user for desired operations.

It is fair to say ArcInfo is a much more powerful program, with many more operations available for the user. Also, ArcInfo is a number cruncher for complex operations that ArcView would not be able to handle. HOWEVER, ArcInfo can be much more complex to use in some cases.  We will have the pleasure of both programs in class.

* As mentioned above ArcInfo is a command line driven program, which means there are several commands that you will need to know in order to move within the ARC environment. We have listed a few:

1. arc

* Type this at the Unix prompt to start the program. After the program is running the UNIX prompt will become an arc prompt.

2. w

* This command does two of functions. If you type w then enter it will tell you which directory you are in, similar to the UNIX pwd command.

* The second function of this command is to move from one directory to another.  If you type,  w  <name of a directory>, you will change your workspace to the directory that you specified.  This is similar to the cd command in UNIX.

3. q

* This command exits out of ArcInfo.

4. help

* This command may be the most important of all. It will open the Arc Online Help Manual. You will become very familiar with this window.  This really is a great reference, use it!!

5. cw (Stands for createworkspace)

* A workspace is a directory which contains coverages, an INFO sub directory, and a LOG files.  The INFO directory created stores information about the coverages contained in your directory, the LOG file is a tracking program that shows everything that is done to the coverages contained in a workspace.  This file comes in handy if you can't remember what process you completed last week and you need to do it again.  Just open the log file in a text editor or use the more command to see what and how you manipulated the coverages.

* cw Creates a directory in which your GIS project work can be done. It is similar to the UNIX mkdir command, except many ArcInfo functions have to be done within a workspace created through this function. The usage is generally:

cw <name_of_workspace>

* Let's turn your lab2 directory into an ArcInfo workspace. Since we already have a folder that we want to use as our workspace we can just convert it.  Type w at the prompt to make sure you are in your lab2 directory. Now type cw .  (that is cw [space] dot)at the prompt. This means: turn my current directory into an ArcInfo workspace.

6. lc

* Lists out the ArcInfo coverages within this workspace. If you type  "lc" then enter you will see that we have none in this directory.  This is similar to the "ls" command in UNIX except that it does not list the entire contents of the directory, only the coverages.  You can also type lg to list out the grids in your workspace, "li" to list out the images, and "lt"to list out the tins.
 
 

4.  Importing Internet Data:

* For this lesson, we will obtain data from the internet and change it into a format that is usable to us.

Downloading Data:

A.  Quit out of ArcInfo by typing q.

B.  Type netscape & at the prompt.

C.  Go to the following URL address: http://www.gisdatadepot.com/catalog/US/61068/group111.html

E.  Click on the blue link that says, "Click here to download: 5547 UTLINE.E00.GZ"

* Clicking on that link will bring up the following window:

*UNLIKE THE IMAGE BELOW, MAKE SURE YOU SAVE THE FILE TO YOUR LAB2 DIRECTORY!!!

F.  Save the coverage in your lab2 directory.

* Make sure that Netscape wants to save the file as "4_utline.e00.gz" and not "4_utline_e00.gz". Sometimes Netscape wants to remove file extensions or change a "." to a "_".
* Be sure to save it in the correct directory!

G.  Exit out of Netscape. Be sure to exit and not just close.

Importing Data:

1. Gunzip the file 4_utline.e00.gz

2. In the terminal window start ArcInfo by typing arc.

3. At the Arc prompt type import

* Arc will display something like:

import <option> <interchange_file> <output>

* What Arc is telling you is how to enter the arguments for this operation.

* import is the command we are trying to use.

* <option> is asking for what kind of data we are wanting to import. We are trying to import a "cover". Other options might be "grid" or "tin" which we will discuss in the future.

* <interchange_file> is the name of the file we are importing (4_utline.e00).

* <output> is the name we want to call our new file. We will call ours "utilities".

* Put them all together and the command looks like this:

                     import cover 4_utline.e00 wetland

4. Quit out of ArcInfo.

5. In Arcview open the view of Cache Valley we created last week.

6. Add the new theme we just downloaded.

* We just added the new theme onto the view but it does not appear on the view. Click on the button that extends the view to it's maximum. You can see that the wetlands do not appear to be anywhere near Logan. This can be fixed and we will learn how in next lab.

5.  To Import .e00 files into your ArcView project on a pc Click on start and
     then click and hold on ESRI -> ArcView GIS 32 -> Then click on Import71