Lab 9: Introduction to Raster Spatial Analysis

Introduction

This lab introduces raster modeling in ArcGIS Spatial Analyst.  After doing this exercise you be introduced to using this software package to:

Instructions

You will use the online book called Using ArcGIS Spatial Analyst to do this exercise. You can find the book at I:\students\data\GIS\ESRI_Library\ArcGIS_extensions.

Read Chapter 1 and do the Quickstart Tutorial exercises. You can find the exercise data at I:\students\data\GIS\ArcTutor in the Spatial folder.  

Deliverables

Answer the following questions and produce the following outputs. Labs should be typed, well organized, and be stapled together. The lab is due in class Thursday of finals week.

  1. There are many different choices for defining the analysis extent in Spatial Analyst.  Explain what the analysis extent is and describe the options.  Don't use specific filenames in the explanation.
  2. Explain the different cell size options.
  3. Explain both the x and y axes of a histogram for nominal data such as landuse.
  4. What type of raster dataset is the input for a hillshade map?
  5. How do you show the distribution of a categorical variable such as land use and a hillshade of the same area simultaneously on one map?
  6. When you have an interval level dataset such as slope and you reclassify it to an ordinal level, what are the possible classification methods?  Will your choice affect your suitability map results?
  7. What does the value field represent in the ArcGIS raster format?
  8. How do you reclassify nominal data such as landuse?
  9. Building a school is very expensive if it is on a steep slope so you want to weight it high in the raster calculator.  You will make a suitability map similar to the one you made in exercise 2 of the tutorial.  However weight the evaluation as follows: 0.7- Reclass of slope; 0.1 Reclass of Distance to schools; 0.1 Reclass of rec_sites; 0.1 Reclass of landuse.  When you are done doing the raster calculation, export the map as a jpeg and insert it into you lab MS Word document.
  10. What is a cost map?
  11. How did you define cost based on landuse and slope?
  12. What is cost weighted distance as opposed to Euclidean distance?
  13. Calculating the shortest cost path requires a cost distance raster layer, a cost direction raster layer (which defines the direction of the lowest cost) and a destination file.  This type of calculation is called the least cost pathway.  What does the resulting map really mean, the least cost of what?
  14. At the end of exercise 3, export the final map to a jpeg and paste it into your lab MS Word document.