Topographic Survey with Total Station

Introduction

This week we used an instrument called a total station. The set up of the station was done by Martin Goettl and our professor Joe Hupy who then described to us how the set up worked. The place that the total station stands is called the known static point or occupied static point. It is very important that once this station is set up that it does not move at all because it is very sensitive and will throw off all measurements if moved in the slightest bit. It is also very important that you measure and record the height of the total station and the height of the prism (receiver). If you change the height of the prism it is crucial you let your partner know so that change can be recorded.

This station, if properly set up, can record the direction and distance of how far the prism (receiver) is when the laser is shot at it from the total station. This technology was bought around 2007 and although it was state of the art at that time, today there are many other advanced technologies such as a total station that can fix its laser on a moving receiver and lidar. The total station that we used was to create a DEM (digital elevation model) of campus. The difference between the total station and doing a distance/azimuth survey is that the total station is set to true north (using back sites that for us were orange flags) and it measures the Z value (elevation).

Study Area

This study took place in Eau Claire, Wisconsin on the UW-Eau Claire campus. The total station was set up outside between the Davies building and the Phillips building. It was placed in the grass not too far from the side walk. Points were then recorded outward from the station (also known as the occupied static point) in all different directions and all different distances. It was a rainy afternoon as we worked outside but all the equipment was waterproof so it shouldn't affect the data. 

Methods

As I mentioned above, the stations were already set up for us and ready to use. Joe Hupy explained to us how the set up worked and then how to actually use the device. The class was split up into groups of two, my group in particular was a group of three so a student did not work alone. Each group took turns going out and surveying the campus, with our group going first. I first lined up the total station to the prism (reciever), and then recorded the points. I did this for about five points and then we all switched positions. I went out and held the prism and then Ethan lined up the total station and Jesse recorded the points. We did this for another five points and then all switched. Next Ethan held the prism, Jesse lined up the total station and I recorded the points for around 7 points. Then we headed back inside and grabbed the next group to go outside. Each person in each group collected around five points until we got the resulting map below. I should mention that when each point was recorded the latitude, longitude, height and height of the datum was recorded.

Tools used:

• Total station
• Prism (receiver)
• Topcon (GPS)

Figure 1: Total station laser (lined this up to the prism)

Figure 2: Prism (received laser)

Figure 3: Height of prism

Figure 4: Screen of Topcon where the individual points were recorded

Figure 5: The entire set up

Results

Figure 1: Table of values recorded from the Total Station

This was the table of numbers (just a snippet of the table) given to us after each group and person had recorded their points. The first column is the point number, the second column is the latitude, the third column is the longitude, the fourth column is the height and the last column is the height of the datum. We were told not to use the height of the datum. I imported the data into ArcMap by clicking File> Add Data> Add X,Y Data. I then imported the table above and set the X Field as latitude, the Y Field as File Format and the Z Field as Ht (g). This sounds completely wrong but the table had shifted over a column from its actual field name, so a few things got jumbled up. Once I put all of this information in I clicked OK the map below was created. 

Figure 2: Map of Survey Points

This is what the layout of the points looked like after we brought them into ArcMap. Unfortunately I was unable to have a basemap work with the data even after projecting the data to NAD 1983 (2011) Wisconsin TM (meters). Had there been a basemap within this map it would have shown that these points were exactly in the correct spots that they had been recorded in because of how accurate the total station is.