Beyond the basic representation of existing data, ArcGIS can manipulate data through a series of Analyst Tools built into the software. These extensions have to be enabled through the Customize>Extensions menu. Selecting Geoprocessing>ArcToolbox, will open the array of analyst tools available. Tools that might be of particular help with regional mapping will be the Contour, Slope and Aspect tools found in the Spatial Analyst Tool subset.
ArcToolbox Menu Icon:
Analyst Tools Setup:
To turn on all of the ArcToolbox extensions that will be used in this lab, you will need to open the extensions dialog and check each of the analyst tools.
- Check box for all analyst tool extensions
- Select Window>ArcToolbox from the menubar and dock the ArcToolbox on the right side of the workspace.
Lab Files Needed: Mississippi Roads Shapefile, Desoto County Boundary Shapefile, Desoto County DEM, Mississippi Population Density, Shelby County Boundary Shapefile, City of Memphis DEMs
Clip and Extract Tools Exercise:
In this exercise, you will use a boundary file (polygon shapefile) as the boundary to clip a larger set of information. When utilizing only vector data, you will use the Clip tool.
- Add the Desoto County Boundary Shapefile to a blank map
- Add the State of Mississippi Road Shapefile to the map
- Navigate to Analysis Tool>Extract>Clip, or type “Clip” in the search menu.
- Open the Clip dialog and select the Roads as the input dataset and the County Boundary as the clipping boundary.
- Run the command.
There are times where you will want to clip raster data from online servers or your local drive. In certain instances, the clip function will not clip exactly to the boundary. In these scenarios, you will want to use the Extract by Mask tool.
- Add the Shelby County Boundary Shapefile to the existing map
- Access the ArcGIS Online servers and search Mississippi Landcover
- Select and add the landcover pertaining to our region of study
- With both files in the Table of Contents, navigate to Spatial Analyst Tool>Extraction>Extract by Mask or type “Extract by Mask” in the search menu.
- Select the landcover raster as the input raster and Shelby County as the boundary.
- Run the command.
You will notice that a new layer will appear in the table of contents for both of these processes. This data is stored in default geodatabase, though it can, and often should be saved in the location of your preference for future use. The following procedures will allow you to save this newly clipped data.
- Right+Click on the new data in the table of contents and select Data>Export Data
- Change the file destination to the location of your choosing and indicate that the data be saved as a shapefile for any vector data. Raster data will simply stay as raster data.
- You will be prompted to add this layer to your current map, though it is often unnecessary because the data is currently in the map.
- Repeat this process for the other newly created data.
For the completion of this first lab assignment, create an 11×17 layout and export the map to a known scale. Be sure to put a title, scale bar, scale text, and north arrow in the layout. Save it as a pdf and submit via email as “lastname_firstname_lab01”
Landcover and other similar data can visually indicate the spatial patterns on the data. The attribute table of the data can provide quantitative data for each type of cover, and ultimately percentages. Using the attribute table, what percentage of the land cover is Developed, High Intensity?