# Tracking Creatures of Bavarian Folklore Using a Least-Cost Path Model

## Preparing the Data

The following Skill Drills for preparing the data use the knowledge you have learned in previous courses, including Geospatial Concepts (GSP 101) and Geographic Information Science (GSP 270). Therefore, the instructions do not contain many step-by-step details. You should refer to previous coursework if needed. Registered students may also post questions on the weekly Q&A Discussion Forum on the Canvas LMS.

## Skill Drill: Adding the Den Locations as XY Data

In this scenario, HSU students recorded the location of several wolpertinger dens using hand-held GPS receivers. Information about these dens, including location and the identification number, is available in a comma-separated value (CSV) file.

If you are a registered student at Humboldt State University, you may access the data used in this lab by logging into the course using the Canvas LMS. Find the link to download the data on the assignment page in Canvas. Download and then decompress the file into your original folder.

A GPS receiver set to WGS 1984 was used to obtain the geographic coordinates in decimal degrees. It’s important to remember that each geodetic datum as a unique set of latitude and longitude values. For example, the latitude and longitude values for your home using the North American Datum of 1983 will be different than the latitude and longitude values using the North American Datum of 1927. Likewise, the World Geodetic Datum of 1984 (WGS 1984) will use yet another set of latitude and longitude values to define the location of your home. Like most latitude and longitude values, you will obtain from the internet or a GPS receiver, the decimal degrees in this are currently in the geographic spatial reference system WGS 1984. When adding XY data, the ArcGIS software only reads the decimal degrees. It is unaware to which spatial reference system these decimal degree values belong. ArcMap will assume, incorrectly, that the spatial reference is the same as the dataframe. You must indicate in the Add XY data dialog box that this series of decimal degree values belong to the WGS 1984 spatial reference system. If you do not, your den locations will likely end up somewhere in the ocean.

After adding XY data, the ArcGIS software will create a temporary events layer. In many ways, the events layer appears to be similar to a shapefile. However, it is only a temporary representation and does not have an associated database.

Export the events layer as a shapefile and save it to your working folder. You should now have a shapefile of the den locations in the WGS 1984 spatial reference system saved in your working folder. Next use the Project tool to create a copy of the data with the NAD 83 UTM Zone 10 spatial reference system. Add the layer with the correct spatial reference to your Table of Contents and remove the old version.