Lab 04 - Conducting a Distance Azimuth Survey

Introduction

The focus of this lab exercise was how to overcome problems encountered in the field related to properly conducting an accurate survey. In this lab exercise, we gained experience in conducting a distance azimuth survey using a variety of survey methods and technologies. These include higher tech options such as GPS and laser rangefinders, to simpler ones like compasses and measuring tapes. We employed this different methods and technologies to conduct a simple survey of a variety of trees spread around the University of Wisconsin- Eau Claire campus.

Methods

To begin this survey, we first familiarized ourselves with some of the equipment we would be soon using. Some of the simpler equipment like compasses and measuring tapes are quite self explanatory and we all had experience with them. Next we familiarized ourselves with how to use the GPS unit, in this case a Garmin eTrex Handheld GPS, and the laser rangefinder, a TruPulse 360B Laser Rangefinder which can measure both distance and azimuth.

Garmin eTrex Handheld GPS

TruPulse 360B Laser Rangefinder

Using this equipment, our lab group left Phillips Science Hall and headed out to the central area of campus to conduct the survey. Our group was assigned a starting point to the South side of Schofield Hall and then picked five trees to survey. We began by recording the latitude and longitude our starting point that the trees would be surveyed from. This data was recorded in the field at the time of data collection. Still using the GPS unit, the next step was to record the elevation value in meters of each of the trees that were being surveyed. With this data recorded, we then used the laser rangefinder to determine the azimuth in degrees to each of the trees from our initial survey point. This was done by looking through the rangefinder and depressing a button on the top of the unit which automatically determined the azimuth. The next data to be recorded was the distance from the starting point to each of the trees. The laser rangefinder was used for some of the measurements, but the low sun shining in created glare and the rangefinder struggled to get an accurate measurement past a certain point. To address this issue, we simply measured the distance from the starting point to each tree using a measuring tape. Finally, each of the surveyed trees circumferences were measured which was used to then calculate the tree's diameter and the tree's species was recorded as well.

With all the data collected, the groups returned inside to enter the data into an Excel spreadsheet, save it as a .csv, and import it into ArcGIS Pro for analysis. The first step of this analysis was to create a point using the collected lat/long that represented the initial survey point for each of the groups. With this done, the Bearing Distance To Line Data Management tool was run. This tool creates line features originating from a point based on a bearing, in this case the collected azimuth data, and a distance, in this case the measured distance from the starting point to the surveyed tree. 

With this tool run, line features originating from the original survey point to the surveyed trees were created. Next, the Feature vertices To Points Data Management tool was run. This tool creates a point at the end of each of the line features originating from the origin create earlier.

With these tools run, all of the necessary map features have been created. The next step was then to create cartographically pleasing maps that visualized the survey area, the survey origin point, direction from the survey point to each of the trees, tree species, tree diameter, and tree elevation.

Results

Conclusion

This field exercise proved troublesome to complete, as some of the equipment that was used either failed entirely or failed to work as well as it was supposed to. Luckily, we had the tried and true methods of simply measuring by hand using a compass and a tape measure that proved useful. Because these methods were not always foolproof, the data seen in the maps above is not 100% accurate and true to the real world. Some of the tree points appear to be slightly off of where they should be and the azimuth's may not be exactly what they are in the real world. In addition to these problems, two groups had difficulty with data collection and entering of said data into the .csv. These two groups failed to properly collect the data and also failed to correctly determine the proper azimuth from their original survey point to each of the surveyed trees, rendering their data useless for this exercise. Even with these errors and troubles, the field exercise was able to be completed well enough to visualize all of the collected data. As seen in the maps, there are a variety of tree species present on Eau Claire's campus. Using the collected data for tree diameter, it can also be inferred that there are trees of a variety of ages present on campus.

Overall this field exercise provided us with a variety of useful field techniques that we can use in future classes or employment. These important skills of conducting a field survey under conditions that are not optimal, in this case because of failing technology, will prove very useful in the future because we are bound to run into some of these problems again.