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For these data to be read by ArcMap, they will need to be converted. This conversion will be accomplished by using various scripts available in the ArcTools program. Our first goal is to transform all data into shapefiles or raster datasets.
The hydrography data must be converted from ArcExport form. ArcExport format was designed for older ArcInfo versions of the ESRI software so it archives data in "coverage" form. The process will be to convert ArcExport data to coverages, and then coverages to shapefiles.
First, unzip the data into your HYD folder. You should be able to do this without guidance by now.
Open up ArcTools from the ArcCatalog menu. So where is the tool to import Arc Interchange files? This is a common problem with ArcTools, just locating the right tool can be difficult. At the bottom of the Arctool file tree window you should see tabs for Index and Search. Try searching for e00, the suffix for the file. You should find that the tool is located under the "coverage tools" category. Start the tool for to "Import from Interchange File". Give the tool the name of your downloaded *.e00 file from the CUGIR site for the Delevan quad. Let the tool choose the other options and start it. When it is finished, you should see a coverage in your Delevan/HYD directory. This coverage has data called arc, node, point, and tic. Previewing the data will tell you that it is the "arc" that resembles the shapefile and is what we are really after.
Covert the arc data to a shapefile by right clicking on the "arc" data, choosing Export... and then to shapefile (single). Choose the HYD folder for output and name the file delevanhydshp. Start the tool and it should create the shapefile. Look at the properties for this shapefile. Notice that the spatial reference (under the Geometry Entry, remember) is UTM NAD27 18N. The spatial reference has been retained with the conversion of the shapefile. Change this projection to NAD27 17N to match the projection from your previous Machias Map project. As you may recall, you can do this by right clicking on the dataset, going tp properties, Field Tab, and clicking on the Geometry properties under Shape. Click on the elipses ... to select the new projection.
Now we want to import the metadata that you downloaded from the site. Click on the shapefile in ArcCatalog and choose the metadata tab. The metadata may have been imported when you converted the coverage to the shapefile, but you will want to make sure you have the correct metadata. Import the metadata from the XML metadata file that you downloaded.
To import the metadata:
In the Catalog tree, click the item for which you want to import metadata.
Click the Metadata tab.
Click the Import Metadata button
on the Metadata toolbar.
Click the Format dropdown arrow and click the format of the metadata that you will be importing. In your case, you chose to use XML data..
Click the Browse button.
Navigate to and click the metadata file whose contents you want to import, then click Open.
The metadata will be loaded into the shapefile. Browse through the metadata. You will see information about where the data came from, the spatial references, even links to how hydrography line data are created by the USGS. Preserving metadata is the core component of data quality in GIS systems. Whenever possible, you should down load metadata with data from external sites. Data on the CUGIR site adhere to FGDC metadata standards. The Federal Geographic Data Committee (FGDC) is an interagency committee that promotes the coordinated development, use, sharing, and dissemination of geospatial data on a national basis.
Repeat this process for the West Valley quad hydrography data, including importing the metadata.
Digital Raster Graphics are generally digital image versions of paper maps. In this case, the DRG is a quad map. DRG's include spatial information that allows them to be overlayed with other spatial data in a GIS. Because raster data are generally very large, providers use a variety of techniques to break up the data in to bits that can be stored and displayed efficiently.
Unzip the dataset into your DRG directory. You should create a new directory that has a large number of *.tif files. These *.tif files are individual image files, each with geolocation data associated with them. Use ArcCatalog to browse this directory and preview some of the tif files. You will notice that each tif file covers only a fraction of the quad. To include all of the details that are present in quad maps, the resolution of the images must be very fine. As a consequence, it is often not efficient to display the whole map at once. For us, however, we will go ahead and make on big raster dataset out of these individual sets.
Under Data Management Tools.. Raster, open the Mosaic to New Raster tool. This tool will combine the individual tiff files into a new ESRI format raster dataset. Indicate the folder where you want the new raster dataset to be placed (your DRG directory) and indicate that you want the new dataset named to be named "delevandrgmos". Let all the other parameters go to default and let the tool create the new raster. This could take a while in the lab because you will all be writing over the network. If you want to speed up the process (by a factor of 3 at least) you can write to the c:/temp directory and then copy it into your class directory when it is done running.
In catalog view you will now see a new raster dataset named delevandrgmos. If you preview this dataset you will see it now covers the entire quad. Import the metadata for the raster data as you did before, using the xml dataset you downloaded from the CUGIR site. Notice that mosaicking all the data allows you to assign the metadata to a single file. This would have been quite a chore for 12 individual tif files.
Check the properties of this new file to determine the spatial coordinate system. It may or may not have been imported during the mosaicking process. If the projection is “undefined” we will need to define the projection before we proceed. If you look at the properties of the tiff files that were mosaicked you will find it is UTM 18N NAD83. This is also the projection of the mosaicked file. To define the projection, use the tool Data Management...Projection and Transformation...Define Projection.. to set define the projection as UTM 18N NAD83. Note that you are NOT reprojecting the data, just making sure that the data has projection information. You should get in the habit of constantly checking data to assure that the spatial coordinates are defined.
Once the mosaic image has a defined coordinate system we can reproject into the desired UTM 17N NAD27. Under Database Management... Projections and Transformations...Raster... you will see the Project Raster tool. Start the tool and enter the mosaic raster as the input raster and a renamed output raster name that isn't more than 16 characters (e.g. delemosnad27). For projection, choose UTM 17N NAD27 (CONUS). Alternatively, you can import the projection information from the HYD shapefile. Again, if you write to the c:\temp directory the process will be much quicker, but it will take between 1 and 5 minutes.
When you look at the metadata in the results, you will notice it is empty again. Import the metadata you downloaded (XML) again, making sure to choose to "Update Metadata Automatically". If you look under Spatial Details again, you should see that the projection info is now UTN17N NAD 27. This is because ArcCatalog automatically updates the metadata with the current projection info.
Repeat this process to create a mosaic image for the West Valley quad, complete with metadata. The West Valley data will be distributed in two folders, but you can add them all at once to mosaic.
The DEM that you downloaded from CUGIR is in ASCII USGS DEM format. To work with it in ArcGIS you will need to convert it to an ESRI raster dataset. First unzip the data into your DEM directory. To convert to ESRI format, use a tool in the Conversion Tools...Raster tool box called "DEM to Raster". Open the tool and give it the name of the ACSII DEM file and an output file name. Make sure that the data type is FLOAT, not integer. This is because the elevations are given within a tenth of a meter in the USGS datasets. Run the tool to create the DEM raster.
Preview the new raster and you should see a grayscale rendering of the topography:
You can use the Information tool (above) to click on a pixel. It should show you the coordinate of that pixel and the elevation. This elevation is meaningless, of courses, unless you know the units and the datum. Make sure that the spatial coordinate system is defined in the file by checking “properties”.
Import the XML Metadata that you downloaded from the CUGIR site into the dataset. You notice that the units of elevation are in meters, and the resolution of the data is given as "1" with a unit of decimeters. This means that elevations are represented with a precision of 0.1 m. This does not mean that the DEM is accurate to within one decimeter, however. To obtain more information about the accuracy of the data, scroll down to "Spatial Data Quality". Green text such as these can be expanded to provide more information about the data. Under this category, you will see headings for horizontal and vertical accuracy. These metadata indicate that the data are accurate with 3 m horizontally, and 6 to 8 meters vertically. This is important to know when you actually start to use these data. It establishes "error bars" on the spatial data.
If you read more about this DEM you will find that it was created by digitizing contoured topopgraphic maps. This means that the DEM is no more accurate than the original 1:24,000 scale quad from which it was created. This quad is represented in the DRG file as well.
Repeat this process for the West Valley quad DEM, including the metadata.
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