Map Rainfall in 3D

William Montgomery, New Jersey City University

Summary
This comprehensive activity introduces students to onscreen digitizing (OSD); automated mapping (Add XY Event Theme); table joins; 3D models; and automated contouring. The exercise has proven useful in helping students understand the genesis, power, and art of contour mapping.

Context

Type and level of course
This activity is comprehensive and relatively advanced in terms of important GIS-related skill sets, but is suitable for insertion into the middle of an introductory (200-level) GIS course.

Geoscience background assumed in this assignment
No Geoscience background is required, although experience with contouring would be a significant advantage to reap maximum benefit from the activity.

GIS/remote sensing skills/background assumed in this assignment
The student should:

be able to perform onscreen digitizing (OSD) of points by using their Lat-Lon coordinates and the ArcGIS map view;
recognize X (E-W or Longitude) and Y (N-S or Latitude) coordinates
be able to identify a unique "primary key" for 1:1 Table Joins
grasp the concept of a "z" value as a mappable quantity (e.g., elevation or amount of rainfall)

Software required for this assignment/activity:
ArcView/ArcScene 8 or 9.x with 3D and Spatial Analyst Extensions

Time required for students to complete the assignment:
4-8 hours, depending upon skill level and reading ability

Goals

GIS/remote sensing techniques students learn in this assignment
Students learn how to:

Build a point map through OSD
Build a point map by adding an XY Event Theme
Prepare tabular data, including creation of a unique identifier (ID) field
Convert MS Excel data to DBF format w/ Excel and/or Access
Perform a Table Join of rainfall amounts to hypothetical rain gauges
Create a 3D model (TIN) of rainfall data with 3D Analyst
Classify the 3D model in an intuitive (Equal Interval) manner
Create contours of rainfall amounts using TIN with 3D and/or Spatial Analyst
Manipulate the 3D model (pan, zoom, etc) for maximum visual effect

Other content/concepts goals for this activity

Higher order thinking skills goals for this activity
The student should be able to employ 3-dimensional visualization to better understand the ways that contour mapping can be employed.

Description of the activity/assignment

This activity places the student into a role as the new GIS expert for the State of New Jersey whose task is to join two different tables of data together (30 rain gauge station locations across NJ and rainfall amounts for each station), create a 3D model of rainfall with 3D Analyst, and contour the data with either 3D Analyst or Spatial Analyst. The activity is very comprehensive in terms of the broad variety of skill sets that need to be mastered in order to complete the activity.

Determining whether students have met the goals

The successful student:

Creates reasonably well-located points through OSD
Creates an XY table in MS Excel and properly convert it to DBF format, either through Excel or MS Access (MS Office 2007 and later)
Creates a map of accurately located and identified points through automated XY Event Theme mapping
Creates proper ID columns and perform a successful table join of rainfall amounts to the appropriate rain gauge stations
Uses 3D Analyst to create and classify a TIN in 5-inch increments using rainfall amount as the "z" variable
Uses 3D Analyst and/or Spatial Analyst applied to the TIN to create a contour map of the rainfall data at a 5-inch contour interval
Creates an appropriate map layout with Scale Bar, Legend, Title, and North Arrow
Captures a "screen shot" of a 3D view with the TIN in ArcScene
Exports both the ArcMap layout and 3D ArcScene view as JPEGs and Inserts the JPEGs into a short report that describes What the student did, and Why.

More information about assessment tools and techniques.