Introduction to Geographic Information Systems in Forest Resources

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Objective:

• Download GIS data from the web and import to ArcView.
• Find information about data sources by using the National Spatial Data Infrastructure Clearinghouse.

1. Set up your directories
2. Download and import data from the USGS GeoData web site
3. Find GIS data on the web, download and import
4. Search the NSDI Clearinghouse
   
5. Download SDTS DEM data
6. Convert SDTS DEM to USGS DEM
7. Import USGS DEM
8. Download SDTS DLG data
9. Convert SDTS DLG to DXF
10. Convert DXF to shapefile
11. Get and view USGS DRG data
12. Convert SDTS DLG to ArcInfo coverage
    

Set up your directories

1. Open the Windows Explorer to your Zip disk.
   
   
2. Create a directory called grand_coulee. Within the grand_coulee directory, create a directory called masterdd and another directory called data. Your file system layout should look like this (with the drive letter for your Zip drive):
   
   
   
   
3. Start the Microsoft Internet Explorer (do not use Netscape).

1. Go to the USGS page for download of physiographic data.
   
   
2. Download the Physiographic regions data set (physio.e00.gz) set into your working directory. (If the site is down, retrieve this copy.)
   
   
3. Download this copy of the gzip compression utility, and place it your working directory (or use the one on CD:\unix).
   
   
4. Open a command prompt (Start > Programs > Accessories > Command Prompt).
   
   
5. Use the commands shown below to change drives and to unzip the gzipped file.
   
   
   
   
6. Start ArcView.
   
   
7. From the Windows Start button, navigate to the place where you normally start ArcView. You will find Import71 in the same place. Start Import71.
   
   
8. Enter the full path names of the files in the dialog, or use the Browse button for the Export File and the Output Data Source directories.
   Note that if you browse to an Output Data Source directory, you will still need to enter the name of the data set you wish to create. In this example, the new data source will be saved in D:\, but the data source will be called physio. The Output Data Source does not need to have the same name as the export file, but it is customary to call the output data set by the same name as the interchange file. In any case, there is a 13-character limit on the file name of the output data (do not use spaces, either!).
   
   
   
   
9. Click OK.
   
   After the import completes, the utility will report a completion:
   
   
   
   
10. This creates the theme specified in the Output Data Source.
    
    
11. Add this theme to a view. Note that because this is an ArcInfo coverage data set, it does not have the .shp file extension.
    
    
    
    
12. ArcInfo coverages (if built properly) will have projection information listed in a file in the coverage directory. Use the command prompt to list the contents of the file:
    
    
    
    
13. Since you know this data set is stored with these projection parameters, create a new view using USA data from the esridata\usa directory from the CD. Alter the view's projection properties to match the projected data set
    
    
    
    
14. Save these themes in projected units. Now you will have several data sets all projected in the same system, and they can be used together in the same view.
    
    
    
    
    

You have just downloaded a GIS data set in ArcInfo Interchange File format from the web and imported it into ArcView. You have also projected some unprojected data sets to match the data you downloaded and imported. Many of the data sets available on the web are in this format.

1. Search the web using Ixquick, MetaCrawler or Dogpile for the phrase "GIS data" or "E00" or "ARC+Interchange+File" (use the quotes to search for the entire phrase).
   
   
2. Based on the response, find an ARC Interchange file on a web or on an ftp site.
   
   
3. Download and import the file.
   
   
4. Open a Windows Explorer. You will see a directory ("folder") that has the same name as the data set you imported. This is the "coverage directory."
   
   
5. Add the imported coverage to a new view. Note that there may be multiple feature types in the imported data source. If this is the case, add each different source as a theme.
   
   
6. Save each of the theme(s) as a single or a series of shapefiles.
   
   
7. Create a new directory on your zip disk called data_bak.
   
   
8. Using the Windows Explorer, copy all of the individual files for your shapefiles to this new directory.
   
   
9. Add these new copies shapefiles to a view. They should work fine.
   
   
10. Using the Windows Explorer, go back to the directory where you imported the data set in step (3). Copy only the coverage directory (not the info directory) to the same place where you moved the shapefiles.
    
    
11. Attempt to add the data source from the previous step. You should see no such theme listed as a data source when you navigate to the new directory.
    This is because the info directory has not accompanied the coverage directory. Arbitrarily moving directories without understanding the file structure could have dangerous results. Deleting various directories may corrupt your data sources. Deleting info directories will definitely corrupt any ArcInfo data sets in the parent directory.
    

Do you see now why the Manage Data Sources is included in ArcView, and why it is important to be have mastery over the hierarchical file structure?

Searching the Clearinghouse is done by using a forms-based or Java-based interface. Enter various query properties, including which database to search, spatial location, and keywords.

1. Open a new web browser pointed at the Washington State Node of the NSDI Clearinghouse Gateway by right-clicking on the link and selecting "Open in new browser" or the equivalent. Select one of the servers you see on the map.
   
   
   
   
2. From the next web page that displays, select Search Clearinghouse sites using place names.
   
   
3. Click the radio button for Don't search based on time period. This will make a more liberal search for data.
   
   
4. Enter a full text search for "Elevation"
   
   
   
   
5. Use the Washington State Geospatial Clearinghouse Node. If the Washington State Node is unresponsive, select another node.
   
   
   
   
6. Click the Search button.
   
   
   
   
   After a minute or two you will be presented with a series of metadata records for various data sources. The metadata records describe data formats, contact information, time period, etc. Your search results should look something like this:
   
   
   
   
7. Click the link for Washington State Geospatial Clearinghouse - All Nodes. This will return a list of all metadata records with the word elevation anywhere in the record.
   
   
   
   
8. Click the Full record for one of these data sets to see the complete FGDC-format metadata record for the data set. You should see all kinds of important information, such as projection and coordinate system parameters, contact data, file type, source scale, etc.
   
   Here is an excerpt from the Washington State Elevation Data Layer:
   
   
   
   
9. Search for other data on this server and on other servers. Do you find anything useful or interesting? Some of the data sets described will have online linkages to actual data sources.

You have just searched the National Spatial Data Infrastructure for Federal Geographic Data Committee (FGDC) formatted metadata. This should give you an idea of the wealth of GIS data that are available, and how you can begin to track down data.

1. Enable the Spatial Analyst extension (we will need this for importing and displaying DEM grid data sets).
   
   
2. We will be downloading and working with data from the Grand Coulee Dam 7.5 min quadrangle.
   
   
3. Open another browser window and go to the USGS GeoData site (you can do this by right-clicking on the hyperlink and selecting the choice "Open in new browser").
   
   
   
   
4. Click the choice for 1:24,000 DEM. This will instruct you to visit the GIS Data Depot for 7.5 minute tiled DEM data. Click the link for http://gisdatadepot.com/dem on the USGS GeoData web page.
   
   
   
   
5. When you have the GIS Data Depot web site up, click Download Data.
   
   
   
   
6. Follow the links for United States > Statewide Data > Washington > Countywide Data > Lincoln. This will take you to the Lincoln County data sets.
   
   
   
   
7. Find the quad for Grand Coulee Dam. Click the Download button to go to the download page..
   
   
   
   
8. On the Download page, click the link for 1705288.DEM.SDTS.TAR.GZ to download the SDTS-format DEM file. If the download appears to be unbearably slow, get this copy.
   
   
   
   
9. Open a Windows Explorer and navigate to the grand_coulee\data directory on your Zip disk. You should see the SDTS file listed.
   
   
   
   
   
10. If you want to use the most efficient (expert user) way of extracting the file, download this copy of the tar executable to the grand_coulee\data directory on your zip disk. If you want to use the slower and more cumbersome, multi-step WinZip process, skip ahead.
    
    
    1. Copy the tar.exe and gzip.exe files from CD:\unix to the grand_coulee\data. These utilities will allow you to unzip the TGZ format archive file.
       
       
    2. Using a command window, move to the Zip drive and the grand_coulee\data directory, then use the tar command to extract the files. Green text shows the commands you need to enter. The red text here is explanatory for what the commands accomplish.
       
       
       
       
    3. Now that you have the SDTS DEM files extracted, skip ahead to importing the data.
       
       
11. If you will be using WinZip, you will need to download and install it. This will not be possible if your computer account lacks the proper privilege. If you cannot install WinZip, you will need to use tar and gzip.
    
    
12. Open WinZip or the unzipping software you have available. Select File > Open Archive (or the equivalent), and navigate to the file you just downloaded. Open the file. WinZip will ask:
    
    
    
    Choose Yes.
    
    
13. From the WinZip menu, select Options > Configuration.
    
    
    
    
14. On the Miscellaneous tab, make sure that "TAR ..." is UNCHECKED, and click OK. If you are not using WinZip, you will need to make the equivalent change in your unzipping software. This step is necessary in order to extract the files correctly.
    
    
    
    
15. Click the Extract button on WinZip's GUI. Navigate to the grand_coulee\data directory.
    
    
    
    
    
16. You should now have all the component files in your grand_coulee\data directory.
    
    
    

You have just downloaded an SDTS format DEM from the USGS web site and extracted the individual files making up the SDTS data set. Most of the Washington state DEMs are available in USGS DEM format, but if you are searching for DEM data for other states, you may encounter SDTS formatted digital elevation data. You will now convert the SDTS data into USGS DEM format, which can be imported within ArcView.

Before the SDTS format DEM can be imported to ArcView, it will need to be converted to USGS format DEM.

1. Download the sdts2dem_dos.exe file from the BLM GIS ftp site to the grand_coulee\data directory. You may need to download the zipped copy and then unzip it.
   If the BLM site is down, or if you cannot find sdts2dem_dos.exe on the site, download this copy.
   
   
2. Using your command prompt window, run the executable. Green text shows the commands you need to enter. Red text is explanatory.
   
   
   
   
3. After the import completes, the prompt will reappear.

You have just converted an SDTS format DEM to a USGS format DEM. The new file can be imported directly into ArcView.

1. Use the instructions provided in the 2nd Raster Analysis exercise (Importing data from generic raster files) to import the USGS format DEM.
   
   
2. Create an analytically hillshaded grid from the elevation grid (Surface > Compute Hillshade from the menu).
   
   
3. Display the hillshaded grid in 256 shades of gray (Gray Monochrome). Make sure that the lower values are black and the higher values are white or you will "see" your landscape in "reverse," where depressions on the landscape appear raised, and high places on the landscape appear sunken. In order to do this, click the flip symbols button on the legend editor .
   
   

   incorrect

   correct

   
   The dam is clearly visible on the western side of the DEM, spanning the Columbia River.
   
   This is cool to look at in a 3D Scene:
   
   
   

You have just completed the process of downloading a digital elevation model in SDTS format, converted SDTS to DEM format, imported into ArcView, and created an analytically hillshaded view of the Grand Coulee Dam 7.5 minute quadrangle. You should be able to repeat this process for any area in the USA that has SDTS DEM data.

Next, we shall download and import some vector data.

1. Navigate to the USGS GeoData site in your other browser window.
   
   
2. Select the choice for 1:24 K DLG.
   
   
3. Select FTP via Graphics. Follow the link for Conterminous 48 states. Click on Washington state.
   
   
   
   
4. Click the area highlighted below. This contains the Grand Coulee Dam quadrangle.
   
   
   
   
   
   
5. Click the Grand Coulee Dam quadrangle. This will open a link to the parent directory for the files.
   
   
   
   Click on the link for GRAND COULEE DAM, WA.
   
   
6. Enter the hydrography directory and download the 911965.HY.sdts.tar.gz file, but save it locally in the grand_coulee\data directory. Only if the USGS server is unresponsive, get this copy.
   
   
7. Use the same method as before (either the tar executable, or WinZip) of unzipping the 911965.HY.sdts.tar.gz file.

You have just downloaded an SDTS format vector data source from the USGS and recreated its native multi-file format. SDTS is a file format that has specifications for storage and interchange of fully-attributed vector data as well as raster data.

Before we can use the SDTS vector format data, it must be converted to a form that ArcView can read. ArcInfo has SDTS importing functionality, but because we cannot assume that everyone has ArcInfo, we'll stick to some public-domain tools.

The sdts2dxf.exe program (also from the BLM) will convert SDTS vector data into AutoCAD DXF, which can be read directly by ArcView. If the BLM ftp site is down, you can get a copy here.

1. Download the executable into the same directory where your other data reside.
   
   
2. Open a command window and navigate to your grand_coulee\data directory . Review the syntax if you have forgotten how to change drives and directories.
   
   
3. Verify the names of the files you have recreated and run the sdts2dxf command. Note that the prefix for all of these files is hy01. Also note that some of the files have the suffix 01 in positions 7 & 8 of the file name. The prefix and the suffix will be necessary in a moment.
   
   
   
   
4. Verify that you have created a DXF file.
   
   

You have just converted an SDTS file to a DXF file, which will be able to be loaded into ArcView according to instructions in Adding Themes to Views & Legend Editing.

1. Following the instructions for loading CAD themes, load the all 4 of the different data sources from the DXF file.
   
   
2. Save the line type as a shape file called coulee_hydro.shp.
   
   
   
   
   
3. Open and browse the attribute table for the new line shapefile

There is a basic problem with this method. Although we have recreated line data, imported it to ArcView, these lines have no attribute values. In addition, all polygon features are not converted or displayed properly. In order to do a full conversion, you will need to use ArcInfo or some other commercial software.

The last step in looking at the Grand Coulee area will be to download and view the scanned USGS 7.5 minute quadrangle digital raster graphic (DRG).

1. Visit the WAGDA page for digital raster graphics and find the Grand Coulee Dam quadrangle (within the larger Ritzville quad).
   
   If the download seems to be exceedingly slow, or if the link is dead, you can download a local copy of the files (both image and world file in a single Zip file). Download the file o47118h8.zip and unzip it.
   
   
2. It will unzip to o47118h8.tif, o47118h8.tfw, and o47118h8.tfw83. The larger TIFF file is the image itself, and the other two files are world files, one for UTM NAD27, and the other for UTM NAD83.
   
   
3. Make sure both the image and the world files are in your grand_coulee\data directory.
   
   
4. Load the image into your view. Alter the drawing order so that the image is the first to draw. Zoom into the western side of the map, right at the dam. What is the elevation of the dam?
   
   

There is a method that will convert SDTS vector data to ArcInfo coverages, recreate polygon structures, and recreate attribute values. This method assumes no previous experience with ArcInfo, and will not explain any of the "behind the scenes" functionality.

Note: If you are working in MGH, you will not be able to complete this part of the exercise. If you are a student in Fisheries, Geography, or Urban Planning, you should have lab facilities that have ArcInfo. Other students can use the STF Computer lab in 311 Bloedel Hall. I do strongly suggest that you complete this part of the exercise, so that you can be aware of how to utilize the vast amount of free vector data available from the USGS.

1. Download the SDTS Master Data Dictionary by following the link on the USGS GeoData page. Make sure and retrieve the single tar file MASTERDD for the 24K data sets. If the site is unresponsive, get this copy.
   
   
2. Use WinZip (or the tar -zxvf command as before) to expand the 00MASTERDD_LRG_SDTS.tar.gz file into the masterdd directory you created before.
   
   
3. Download and unzip the sdts2cov.zip file into the grand_coulee\data directory. It will unzip to sdts2cov.aml. This is the ArcInfo macro that will convert SDTS vector data to ArcInfo coverage data.
   
   
4. Change directories back to the grand_coulee\data directory in the command window.
   
   
5. Start ArcInfo from an command prompt (use the arc command to start ArcInfo).
   
   
6. Run the sdts2cov macro to create the ArcInfo coverages (use the command &r sdts2cov). Some output will begin to scroll up the command window. If the routine fails, you probably do not have the directory structure correct (see start of exercise).
   
   
   
   After a few moments the macro will terminate, giving a list of the coverages and the type and number of features created.
   
   
   
   
7. If you feel ambitious, you should convert more data sets over from SDTS to ArcInfo coverage format.
   
   
8. At this time, you should be able to customize display of the data set, browse attribute data, convert to shapefile, or perform any other GIS functionality you have learned so far.
   
   Here is a view containing several of the data sets available for the Grand Coulee Dam quadrangle.
   
   
   

You have just converted SDTS vector data into ArcInfo coverage data. There are a tremendous amount of data sets available for free from the USGS, but many of the data will need to be converted over in this method.

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