Lab 1: Raster Modeling in ArcGIS
Introduction
This lab teaches you how to do raster spatial analysis and introduces map algebra. Put the lab data on your workspace.
Because you will use ArcInfo tools to process the coverage data, make sure there is no "space" in the file path (e.g., "My Documents" is not allowed).
Labs should be typed, include your name, be well organized, and be stapled together. All maps for this lab must be in black and white. You will be marked down for color maps.
Where can I find the lab instructions?
Most of the lab readings are web-based help from ESRI's online ArcGIS Resource Center (http://resources.arcgis.com/content/web-based-help), which provides the most up-to-date and comprehensive ArcGIS software instructions. You need to have internet connection to access these online resources. For this lab, you need to read ArcGIS 10 Desktop Help on the Spatial Analyst extension. Click on the ESRI web-based help link above, click on ArcGIS Desktop Help (or the plus sign) to expand its contents and click on the ArcGIS 10 Desktop Help hyperlink to go to the main page of ArcGIS 10 Help Library (or click here to go directly to the page). Use the Table of Contents on the left pane to find the assigned lab readings.
Instructions
The documents related to Spatial Analyst are in the Professional Library, under the Extensions container. Spend a few seconds to navigate through the Table of Contents of ArcGIS 10 Help Library. Try to find the information on Spatial Analyst. Let TA know if you cannot locate the reading. Skim the topics on "Getting started with Spatial Analyst", "Modeling and solving spatial problems", and "Performing analysis in Spatial Analyst." Make sure you read all the topics in these sections (however, you don't have to follow the hyperlinks unless you want to know more about them). You can use the navigation tool on the upper right corner of the page to advance to the next (or previous) topic. ArcGIS 10's Spatial Analyst Toolbar is different from the previous versions. This could be a good opportunity to learn the new features in 10.
When you have read the 3 sections, go back to the topic - "Accessing 9.x Spatial Analyst Toolbar Functionality in ArcGIS 10." This time, follow each and every hyperlinks in the Geoprocessing tool equivalent column of the big table to learn what these tools are about. You can click on the "Lean more about ..." hyperlink in the summary of the tool to learn more about the tool. You will complete 9 spatial analysis tasks in this lab using some of the tools you read about. Please follow the instructions below and produce maps as specified in each task. Make sure you save your results from each question.
Log onto the Oregon Geospatial Enterprise Office web site and click on "Spatial Data Library Alphalist". There are six columns in the table. The E00 file is an ArcInfo interchange file (also called an ArcInfo Export file). ShapeFile is an ArcView shapefile. GRID is an ArcInfo raster data file. Metadata is descriptive information about the data.
Set up for Spatial Analyst Exercises:
1) Download data with the specified format, and unzip them:
= Click on the Shapefile for County Boundaries- Oregon (2007 BLM 1:24,000).
= Save it to your workspace.
= Navigate to the file using Window's Explorer.
= Right-click on the zip file and point to 7-zip to extract (unzip) its contents.
= Repeat this process to download and unzip the following E00 files:
o Cities (USGS, 1:2,000,000),
o Highways (USGS, 1:2,000,000),
o State Boundary (USGS, 1:2,000,000), and
o Vegetation/Species (Oregon GAP vegetation, 1:250,000).
o Population and Land Cover: copy lab1_data.zip from the I: drive at Students\Instructors\dbanis\GEOG492_592\Labs\Lab1_Raster
2) Convert the E00 files into ArcInfo coverages.
= To avoid confusion, it's best to save these coverages in a new folder, separate from the files that you unzipped. Make sure there is no space in the file path name.
= Open ArcToolbox, and search for Import from E00 and then choose the first E00 file and an output name and location for the coverage.
= Import each of the other files into ArcInfo coverages in the same way.
3) Add data to ArcMap
= Start ArcMap and open a new empty view.
= Click the -ADD Data- button and add all of the ArcInfo coverages and shapefiles to your map by double-clicking on them individually and choosing a feature type.
o For each coverage, you will specify the feature class that you want to add to the map (coverages and geodatabases may have multiple feature classes while shapefiles only have one type of feature per data set). The feature classes used by this exercise are:
< Highways - arc
< State Boundary - polygon
< Counties - polygon (shapefile)
< Population - point
< Vegetation/Species - polygon
< Cities - point
< NLCD - raster (this dataset only covers 6 counties)
= Once all of the data layers are added to the map, right-click on the data frame properties at the top of the table of contents (named 'layers').
= Click on the general tab and choose feet for the map and display units. If these fields are grayed out, then first set the linear unit to foot under the coordinate system tab and modify button - hit 'Apply', then set the units under the general tab.
4) Projection information - Check this in the Coordinate System tab under Layer Properties:
The projection information was imported with the coverage. If any data you brought in doesn't have its projection information defined, then you would have had to put this information in manually (using the Define Projection tool). The projection parameters are as follows:
Projection: Lambert Conformal Conic
Datum NAD83
False_Easting: 1312336.0
False_Northing: 0.0
Central_Meridian: -120.5
Standard_Parallel_1: 43.0
Standard_Parallel_2: 45.5
Scale Factor: 1.0
Latitude_Of_Origin: 41.75
5) Now set the Spatial Analysis options as follows - Under the Geoprocessing menu, click on Environment settings and change the following:
= Processing Extent: use the Oregon State Outline file
= Under Raster Analysis, Set Cell Size to "As Specified Below" from the dropdown menu, enter 5000 in the text box below
These two must be done before you begin your raster processing each time you open ArcMap or you will get incorrect results!
You will now do several spatial analyses using the Spatial Analyst Toolbox:
To make Spatial Analyst raster layers permanent, be sure to check the output location and name for the result raster in each tool.
= For all the maps you will submit and be graded on the following...
o Make sure that the SA# is part of their title
o Identify the tool used for each map in a text box or with the title/subtitle
o All maps must be in the shape of Oregon. This may be done many ways. Here is one - Clip to Shape
< Right-click on the dataframe and select Properties
< Select the Data Frame tab
< In the bottom section, under 'Clip Options' select Clip to Shape from the dropdown menu
< Click 'Specify Shape'
< Select 'Outline of Features'
< From the dropdown menu choose the Oregon state boundary layer
< Click OK, the click OK again
o Change the symbology of the state boundary to be hollow with a 2 point outline.
o Change the symbology of the counties to be hollow with a .4 point outline.
o Make sure the correct datasets are displayed with your raster results to make them understandable - not all maps need all the data!!
o Include ALL appropriate map elements on EVERY map as per the lab syllabus. (There is one map where a legend is not needed.)
SA #1: Calculating Distance from Highways using the Euclidean Distance Tool
= Under the Spatial Analyst toolbox choose Euclidean Distance.
= Use the highway coverage as the Input source.
= Make a map of the result.
SA #2: Allocating Space using the Allocation Tool
= Under the Spatial Analyst toolbox choose Distance, Euclidean Allocation.
= Use Cities as the Input source
= Make a map of the result, including a text box on the map describing the map and how it was generated in your own words.
SA #3: Calculating Population Density using Density Functions
= Under the Spatial Analyst toolbox choose Kernel Density
= Use the population layer as the input data
= Set Population Field to POP98
= Set Search Radius to 100,000
= Rerun the tool with a search radius 500,000
= Make a single map that has both results (you will need to use a second dataframe). Include a legend for each that shows the numerical values for the population density. Include a text box describing which density map is better and why.
SA #4: Highway Accessibility by County Using Zonal Statistics
= Under the Spatial Analyst toolbox choose Zonal, then Zonal Statistics,
= Set Input source to the county shapefile,
= Set the Zone Field to alt name
= Set Value Raster to the result of SA#1 (Euclidean Distance From Highways)
= Make a choropleth map with a classified legend using the zone mean statistic, and include a text box describing what the units mean.
SA #5: Rasterize a Vector File and Use it To Calculate Vegetation Diversity Using a Neighborhood Statistic
= Convert the vegetation coverage to raster.
o Under the Conversion toolbox choose To Raster, Feature to Raster,
o Set Input Features to Vegetation,
o Set Field to com_code
o Set Output cell size to 5000
= Calculate the vegetation diversity in a neighborhood surrounding each cell.
o Under the Spatial Analyst toolbox choose Neighborhood, Focal Statistics
o Set Input raster to the vegetation raster you just made
o Make sure the Neighborhood is a rectangle (3x3) and the units are Cell
o Set Statistic Type to variety,
= Make a map with a legend of the result, and include a text box describing what the units mean and why they have the range they do.
SA #6: Reclassify the Raster Vegetation Variety Neighborhood Surface into Two Classes.
= Under the Spatial Analyst toolbox choose Reclass, Reclassify
= Set Input raster to the variety surface created in SA#5,
= Set Reclass Field to value
o Click Classify
= Set Method to equal interval,
= Set the number of Classes to 2, click OK
o Note the Old Values and New Values now listed.
= Make a map of the result and include a text box explaining what the different classes represent.
SA #7: Using Zonal Statistics Tabulate Area to Determine the Percentage of Landcover Classes by County
= Under the Spatial Analyst toolbox choose Zonal, then Tabulate Area.
= Set your county layer as your input feature zone data and set Zone field to CNTY_CODE
= Set the input raster to the NLCD dataset and the Class field to VALUE.
= Change the output table name to something you will recognize and save it to your drive.
= Using the output table and the attribute table for the NLCD layer figure out the class with the highest percentage in each county.
= Make a map of the NLCD layer symbolized by land cover type. Include a text box that explains how the tabulate area tool works and the units it reports. Also include the name and percentage of the highest land cover class for each county.
SA #8: Using the Raster Calculator to Change Cell Values (to m from feet), the Reclassification Tool to Reduce the Number of Classes, and Vectorization
= Under the Spatial Analyst toolbox choose Map Algebra, Raster Calculator.
= Double-click on the distance to highways raster created in SA#1, click on " / ", type 3.28, and click OK.
= Reclassify the result into 3 natural breaks classes.
= Convert the raster to a vector by choosing the Conversion Toolbox > From Raster > Raster to Polygon (it doesn't matter which field you use for this operation).
= Make a map of the result that symbolizes based on GRIDCODE and include a legend with non-numerical labels.
SA #9: Implementing
Map Algebra Commands Within the Raster Calculator
First review
Appendix A of the tutorial book. The Spatial Analyst Raster Calculator allows you to use all
ArcInfo MapAlgebra GRID commands and functions. Learning map algebra is
like learning any language. Once you know the syntax then you need to
increase your vocabulary. In this exercise you will implement one map
algebra function using the Raster Calculator.
= First rasterize the highway vector coverage (using the Highway ID field) that you downloaded and call it HW.
= Then choose from the Start Menu: All Programs > GIS > ArcInfo Workstation > ArcDoc
= Select Contents > Command Reference for ArcInfo Extensions > GRID > Alphabetical List of Grid Functions. This is a comprehensive help system for ArcInfo Map Algebra. Read the help topic for Thin.
= Open raster calculator and type: Thin ("HW") and then click OK.
= Make a map of the result and include a description of the result and how it was generated, and a description of how the THIN command works in a text box.