Creating a Topographic Survey for the UWEC Campus

Topographic Survey

Introduction:

When conducting a survey of points that need absolute accuracy, such as points for construction, a survey grade GPS is used. The goal of this activity was to become familiar with the basics of how one of these systems works and some of the advantages of this tool. Attributes would be collected with millimeter accuracy and placed over an imagery basemap to display the features collected.

Methods:

A Topcon Survey GPS was used to collect points in and around the parking lot to the South of Davies Student Center on the University of Wisconsin Eau Claire campus. Attributes being collected included trees, garbage cans, mailboxes, and light posts. The accuracy of the station can be set up depending on the accuracy needed for the specific point. The tall staff with the beacon on the top seen below in figure one as the black post, is where the point is collected using the tripod design for stability. A point is collected based on an average of points continually taken. Accuracy is increased from "Auto" to "Fix". An auto point is collected by taking an average of 20 points to create the point feature, a fix point is taken from an average of 30 points. Both points are extremely accurate and the degree of error in the auto point taken in figure one is a potential for 3mm of error.

Different groups switched out throughout the period of surveying so that everyone would get hands on experience. The final list of attributes collected where put into an Excel spreadsheet which could then be added into ArcMap by "Add XY Data". The surveyed points appear with a high degree of accuracy on a basemap of the campus.

Figure 1: The Topcon Survey grade GPS was set up to collect attributes including trees, trash bins, mailboxes, and light posts.

Discussion and Conclusion:

The process of actually collecting and setting up this GPS is remarkably simple. It is essentially the same thing as a simple hand help GPS only this system is accurate to the millimeter. From the surveyed points a map of the area behind Davies Center could be created. While this is a simple application for such an advanced tool it is obvious that much more advanced applications could be used and points could be gathered to a high degree of accuracy where it actually meters. The biggest issue for me in this lab cam from the fact that the points collected and placed into an attribute table were in decimal degrees and had a massive amount of issues being projected onto a basemap. I could add the points and the would appear correct based on relative location and orientation in the ArcMap workstation however a basemap could not be projected under the points in the right location. Several attempts were made at reprojecting points and setting coordinate systems and projections yet I could not get the two to agree. This is an issue I have been able to solve before and certainly one I will continue to work on as correcting this is an essential skill.