Lab 2: Raster Modeling in ArcGIS

Introduction

This lab teaches you how to do raster spatial analysis and introduces map algebra.  Put your lab data on your workspace on the network drive (e.g., Z:). If unsure, ask the TA how to map your network drive or visit this webpage. Because you will use Arc/Info tools to process the coverage data, make sure there is no “space” in the file path (e.g., “My Documents” is not allowed). Answer the questions at the end of the instructions of each exercise and produce the requested outputs.  Return them to the TA by the due date.  Labs should be typed, include your name, be well organized, and be stapled together.

Instructions

Skim Chapters 4, 5, and 6 of the Using ArcGIS Spatial Analyst pdf (Using_Spatial_Analyst.pdf) on the I drive  (The pdf file can be found in the I:\Students\Data\GIS\ArcGIS Documentation\ArcGIS9.1_documentation\ESRI_Library\ArcGIS_Extensions folder.). Read Chapter 7, do the following tasks, 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 disk in a location that you have access to. 

· Navigate to the file using Window's Explorer. 

· Double click on the zip file to unzip (extract) 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 (USGS). Use this link to download the population data.

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, choose >Coverage Tools >Conversion >To Coverage >Import from Interchange file 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 class. 

· 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 shape files only have one type of feature per data set).  The feature classes used by this exercise are:

· Highways - arc,

· State Boundary – add as a polygon shapefile,

· Counties - polygon,

· Population - point,

· Vegetation/Species - polygon,

· Cities - point. 

· 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 – Can 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 – Make sure the extension is checked and the toolbar is visible:

· Working directory: to one you have write access

· Analysis Extent: use the Oregon State Outline file

· Cell Size: 5000

All three of these must be checked!

You will now do several spatial analyses using the Spatial Analyst menu commands:

· Spatial Analyst creates temporary raster layers. If you want to access them after closing ArcMap, be sure to make them permanent.

· To make Spatial Analyst raster layers permanent, you can either save through the dialog box when you create them, or you can right click on the layer in the Table of Contents and select Make Permanent.

· For all the maps you will submit

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 second section down, under ‘Clip to Shape’

§ Check the box next to Enable

§ Click ‘Specify Shape’

§ Select ‘Outline of Features’

§ From the dropdown menu choose the Oregon state boundary layer

§ Click OK

SA #1: Calculating Distance from Highways using the Euclidean Distance Tool

· Under the Spatial Analyst toolbar choose Distance, Straight Line.

· Use the highway coverage as the Distance to file.

· Make a map of the result, add your name using a text box, and print it.

SA #2: Allocating Space using the Allocation Tool

· Under the Spatial Analyst toolbar choose Distance, Allocation.

· Use Cities as the Assign to coverage.
Make a map of the result and print it with your name.

· Using a text box describe the map in your own words directly on the map.

SA #3: Calculating Population Density using Density Functions

· Under the Spatial Analyst toolbar choose Density,

· Use the population layer as the input data,

· Set Density Type to simple,

· Set Search Radius to 100,000,

· Set Population Field to POP85.
Make a map of the result and print it with your name.  

· Include a legend that shows the numerical values for the population density.

· Using a text box describe what the units mean, directly on the map.

SA #4: Highway Accessibility by County Using Zonal Statistics

· Under the Spatial Analyst toolbar choose Zonal Statistics,

· Set Zone Dataset- to the county coverage,

· Set the Zone Field to alt name,

· Make sure Chart Statistics is checked,

· Make sure Join Output Table to Zone Layer is checked,

· Set Value Raster to the result of SA#1 (Euclidean Distance Surface From Highways)..
Then make a choropleth map with a legend using the Oregon County vector coverage by using the zone mean statistic as the attribute.  

· Use a text box describe what the units mean, directly on the map.

SA #5: Rasterize a Vector File and Use it To Calculate Vegetation Diversity Using a Neighborhood Statistic

· Convert the vegetation coverage to raster.

· Under the Spatial Analyst toolbar choose Convert, Features to Raster,

· Set Input Features to Vegetation,

· Set Field to com_code.  

· Calculate the vegetation diversity in a neighborhood surrounding each cell.

· Under the Spatial Analyst toolbar choose Neighborhood Statistics,

· Set Input Data to state vegetation raster,

· Set Field to value,

· Set Statistic Type to variety,

· Make sure the Neighborhood is a rectangle (3x3).  

· Then make a map with a legend of the result.

· Using a text box, describe what the units mean and why they have the range they do. (You may want to change the number of classes so that the values in the legend make sense.)

SA #6: Reclassify the Raster Vegetation Variety Neighborhood Surface into Two Classes.

· Under the Spatial Analyst toolbar choose Reclassify,

· Set Input raster to the variety surface created in SA#5,

· Set Reclass Field to value,

·  Click Classify

· Set Method to equal interval,

· Set the number of Classes to 2.  

· Then make a map of the result.  

SA #7: 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 toolbar choose Raster Calculator.

· Double click on the distance to highways raster created in SA#1, click on /, type 3.28, and click Evaluate.  

· Then reclassify the result into 3 natural breaks classes.  

· Then convert the raster to a vector by choosing Convert, Raster to Features from the Spatial Analyst menu (it doesn’t matter which field you use for this operation).  

· Then make a map of the result that includes a legend.

SA #8: 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 Programs -> ArcGIS -> ArcInfo Workstation -> ArcDoc and select Contents -> Command Reference for ArcInfo Extensions -> GRID -> Alphabetical List of Grid Functions. This is a comprehensive help system for ArcInfo MapAlgebra.  Read the help topic for Thin.  

· Then open the raster calculator and type: thin([HW]) and then click evaluate.  

If it works then you have implemented your first MapAlgebra command that is not available through buttons or menu commands within Spatial Analyst.  Make a map of the result and include a description of the result in a text box as well as your name.