Lab 6: Interpolation and Geostatistical Modeling in ArcGIS

Introduction

This lab teaches you how to do interpolate surfaces and do geostatistical modeling in ArcGIS.

 

Instructions

The pdf of the instructions (please do NOT print) can be found on the I: drive under Students\Data\GIS\ArcTutor\10\ArcGIS_10_Tutorial_PDFs\extensions as "geostatistical-analyst-tutorial.pdf". The tutorial data can be found on the I: drive under Students\Data\GIS\ArcTutor\10. Copy the whole Geostatistical Analyst folder to your own drive and use this as your workspace for this lab.

 

Read the introduction and do all the tutorial exercises. Answer the following questions and produce the following outputs. Labs should be typed, include your name and lab number, be well organized, and be stapled together. All the maps in this lab must include all map elements (legend, scale, title, N arrow, explanatory text if needed, name, source, date).

 

You should create the maps for this lab as you move through and not all at once at the end. Also, consider the arrangement of layers. Having a raster over a vector layer covers information and is not appropriate.

 

Geostatistical Analyst Questions

Ex. 1 Creating a Surface

  1. At the end of Exercise 1, make a map of the Default Kriging and Ozone points.

 

Ex. 2 Exploring your Data

  1. Are the mean and median values of the ozone layer similar?  What does this tell you?

 

  1. Click on the histogram bar with the lowest ozone values.  Where are the lowest ozone levels in California?

 

  1. What can the QQ Plot tell you when you are looking at one variable?

 

  1. What does the trend analysis graphic tell you about the East-West and North-South trends in ozone levels in California?

 

  1. In Exerercise 2, you created a histogram, a QQ Plot, a trend analysis graphic, and a semivariogram.  Each one of the dialogs for these tools has a button called Add to Layout.  Add all of these graphics to the layout with the interpolated ozone surface, and make a map.

 

Ex. 3 Mapping Ozone Concentration

  1. Read the "Semivariogram/Covariance modeling" section of the tutorial carefully. After you change the lag size, click "More" in the bottom right of the Geostatistical Wizard window. This will open the help entry on Lag Size. Read the help document too. What are lags? Why is the selection of an appropriate lag size important?

 

  1. Read the "Directional semivariograms" section of the tutorial carefully. After you change anisotrophy from False to True, click "More" in the bottom right of the Geostatistical Wizard window. This will open the help entry on trends. Read the help document too. What is anisotropy? How is it accounted for when a kriging method is used?

 

  1. What is the objective of cross-validation? How do you judge the accuracy of a model?

 

  1. What is prediction error and how do you measure it?

 

  1. What is a prediction standard error map?

 

  1. Print a map of the krigged ozone surface with the trend removed.

 

  1. Print the standard error map of the krigged surface.

 

Ex. 4 Comparing Models

  1. How do you use the cross-validation comparison window to compare surface models?

 

Ex. 5 Mapping Probability

  1. Make a final map at the end of Exercise 5 that includes an inset zoomed-in on the Los Angeles Area and text box explaining the map and inset.