Field Activity #7 Part I: Creating a Navigation Map of the Priory

Introduction

On a basic level, all that is needed for accurate navigation is a tool to aid directional orientation, such as a compass, and a location system, which is usually a map associated with a coordinate system and projection. Which coordinate system and which projection make a large difference in the accuracy of the results; large geographic scales are not reliable for small geographic areas because they do not portray each local area with integrity and distortions become more apparent the more the user “zooms in” to smaller and smaller areas.
In this field activity, each student needed to make two maps for navigation of a local forested area, one with the UTM coordinate system and one with the Geographic Coordinate System in decimal degrees.

What is a coordinate system?

Put simply, a coordinate system is a reference system used to represent the locations of geographic features, such as Global Positioning System (GPS) locations, within the context of where it is on the globe. Coordinate systems enable geographic datasets to use common locations for integration.
 Each coordinate system is defined by the following:

• Its measurement framework, which is either geographic (in which coordinates are imagined on a round globe) or planimetric, a.k.a. projected (in which the round globe of earth is mathematically projected onto a 2D map)
• The definition of the map projection for projected coordinate systems
• Units of measurement
• Other measurement system properties such as a spheroid of reference, a datum, one or more standard parallels, a central meridian, and possible shifts in the x- and y-directions

There are hundreds of geographic coordinate systems and a few thousand projected coordinate systems. Two types that are very commonly used in a geographic information systems are:

Diagram of a GCS. Image from ESRI 

Geographic coordinate systems (GCS) - A global or spherical coordinate system such as latitude-longitude. These are unprojected (not flattened onto a 2D map). The units are decimal degrees. The most popular of all of these is GCS WGS 1984, and that is the coordinate system used for my map.

Universal Transverse Mercator (UTM) - A projected coordinate system that divides the earth into long vertical zones that resemble orange slices. These zones can be further subdivided for better accuracy. The units are typically feet or meters. For my map, I used the coordinate system UTM Zone 15N with meters.

The UTM coordinate system. Images found on google and altered.

 For more information on coordinate systems and projections, check out the ESRI Help page!

Students worked individually on the maps but were placed into an assigned team of three or four for the navigation activity, which will be covered in the next blog post (so stay tuned!). Group 5, a.k.a. team Thundernado, was Anneli W., Jackie S., Jeffrey S., and Amanda (myself). For the navigation activity, a list of waypoints and their associated coordinates will be provided. These points will be manually plotted and located the old-fashioned way, using only a trusty ol’ compass and our map.

The Study Area

Figure 1 Photo by Bill Hoepner, UW-Eau Claire photographer.

The Priory, formerly the St. Bede Monastery, is located three miles south of the UW-Eau Claire main campus. The property, situated on 112 mostly wooded acres, was purchased in October 2011 by a subsidiary of the UW-Eau Claire Foundation for use by the university. It is currently being used as a children's center and has been recently renovated for use as a residence hall (Fig.1).  It is located three miles south of the UWEC campus in a forested and hilly area. Below is a view of the Priory grounds and a map of its location, courtesy of Jacob Henden (Fig.2). 

Figure 2 This is a view of the Priory grounds where the navigation activity will take place. The Priory is a convenient drive from UW Eau Claire’s main campus.   

Objectives

The objective for this week was to make navigation maps that display the navigation area as accurately and concisely as possible. A large suite of data was made available for this project (Fig.3), and it was the responsibility of the student to decide and utilize only the most expedient information in their maps.

• Create two maps: one that contains a UTM grid at 50meter spacing (or finer), and another that provides Geographic Coordinates in Decimal Degrees
• Both maps will contain the following elements:

1. North arrow
2. A scale bar (Meters) and a RF scale.
3. Info about the projection/coordinate system
4. Labelled grid
5. Basemap
6. List of data sources
7. A watermark

Figure 3 This is a sample of the data that was provided by Dr. Hupy. The red box indicated the extent of the navigation area boundary. It encircles the land around the Priory, a property owned by UW Eau Claire.

Methods

Making the maps in ArcMap was an enjoyable challenge. After testing a few options, it was clear that the topographic map and the black & white intensity image would not be very useful on a navigation map. I decided to use the aerial image of Eau Claire as a basemap, knowing the true color imagery would help Team Thundernado get our bearings in the field. I also added contour lines to show elevation changes. The boundary of the navigation area was also provided, but needed to be projected along with all the other data into the desired coordinate system.

For the UTM map:

All the data needed to be projected into the NAD_1983_UTM_Zone_15N coordinate system. Rasters, such as the Eau Claire satellite imagery and the elevation data, were converted to NAD_1983_UTM_Zone_15N coordinate system using the Project Raster tool. Feature classes, such as the navigation boundary, were converted using the Project tool. Then the Clip tool was used to clip the feature classes and rasters down to the extent of the navigation area boundary that was given. Contour data of 2 feet contours was provided by Dr. Hupy, but the lines looked too crowded for use on a navigation map. In order to create a more visually appealing and applicable contour diagram, I ran the contour tool on the clipped elevation map and created contours of 2 meters. Figure 4 compares the two.  

Figure 4 The 2 foot contour lines were provided but appeared too crowded to be useful for a navigation map. Also, the grid was to be in meters, so feet seemed irrelevant. The 2 meter contour lines provide a clearer image of the elevation.

A measure grid of 50m squares was added to aid in navigation (Fig.5). This will help during the navigation by allowing us to visualize scale and distance.

Figure 5 A close-up view of the grid labels. The grid on the UTM map shows every 50m. 

For Geographic Coordinate System map:

All data for this map needed to be projected into the GCS_WGS_1984 coordinate system. Like last time, rasters, such as the Eau Claire satellite imagery and the elevation data, were converted to GCS_WGS_1984 coordinate system using the Project Raster tool. Feature classes, such as the navigation boundary, were converted using the Project tool. Then the Clip tool was used to clip the feature classes and rasters down to the extent of the navigation area boundary that was given. Contour lines were also projected for this. A grid was made for this as well, but adjustments were made to display the decimal degree units clearly.

Results

In hindsight, I would have preferred to use 5m contour lines to alleviate some of the high relief areas from that crowded contour line effect. Overall, however, I feel these maps are very streamlined and would be very useful and accurate for the field navigation next week.

This is the Universal Transverse Mercator coordinate system map which uses meters as a unit. It features a grid of 50m and 2 meter contour lines to aid navigation. The navigation area is outlined in orchid.

This map uses the World Geographic Coordinate System (1984). The units, in decimal degrees, are labelled on the grid. 2 meter contour lines are depicted and the navigation area is outlined in red.

Sources

The Priory provides home for former Children’s Center. (2012, September 1). Retrieved November 1, 2016, from https://www.uwec.edu/news/the-view/the-priory-provides-home-for-former-children-s-center-871 

For Priory locator map:

Henden, J. (2015, May 3). Navigation with Map and Compass [Web log post]. Retrieved November 1, 2016, from http://jacobhendengeog336.blogspot.com/2015/05/navigation-with-map-and-compass.html