Distance/ Azimuth Survey Methods

Field Activity #8

Introduction-

    This lab is intended to show us that you can't always rely on GPS because there can be technical difficulties at times. When the GPS goes down, it is a good idea to have the knowledge and know how to be able to still collect points in the field that are relatively accurate. One way to collect points is through using angles and distance to calculate points, this is called using the azimuth. 

There is a few different techniques used to collect the azimuth, but the easiest and seemingly most accurate happened to be a Tru Pulse Laser (figure 1). The azimuth is a reading between 0 and 360 degrees, and can also be found with using a compass.

Fig. 1 TruPulse Laser 360 allowed for us to read the distance in meters, along with being able to find out the azimuth

Study Area-

    The study area was an exact point outside Phillips hall that all the measurements were conducted from. Since the weather was crappy this day, this lab was a condensed version but still were able to collect enough points to make a detailed map using the azimuth. Click Here below and you can see roughly the location that this experiment was conducted at. Click here. The location was right at the 'Y' in the sidewalk looking towards the north, northeast. The reason this location was chosen was because there was a good starting point were the sidewalk made the 'Y', and there were plenty of trees that we could gain an azimuth reading off of. 

Methods-

    For this activity more than just the azimuth of the tree locations was collected. Also collected were the diameter of the trees, distance from starting point to trees, species, and X,Y location. Figure 2 shows the table that was used to bring the points to life in ArcMap.

Fig. 2 the table and attributes that were collected during the activity.

The first step to collecting these points was to have one person go stand next to the tree while the other was standing at the starting point. The person by the tree would collect the diameter and species type of the tree. The person at the starting point would use the laser finder to collect the distance to the tree and the azimuth. There was a couple of different settings when using the laser finder, but one thing that had to be done was to make sure the distance was read in meters and to have it on the proper setting when recording the azimuth. Looking back at figure 1 there is two buttons on the side of the laser, these buttons would allow one to scroll through the setting until they would reach distance and azimuth. One trouble that the group seemed to experience was reading the different settings and numbers in the laser. It was a chilly, windy, and a rainy day out. These combined to fog up the lenses along with leave moisture on them causing it difficult to read. The only way around this was to continually wipe off the lens before reading the next tree. 

Results-

    Upon the completion of the collection of the points outside of Phillips Hall, we were able to then come back inside to process the points that were collected. A table was setup (figure 2) with all the attribute data collected. It was important to keep this table as simple as possible for the benefit of the tool that was about to be used. The tool used was 'bearing distance to line'. This would give the lines from the starting point to the tree location based upon the azimuth. The next tool used was the 'feature vertices to points' tool. This tool was ran twice seeing that it can select the starting point or the end points "tree points" in this case. The starting point was based off of the X,Y location from the attribute data. The tree points were calculated using the distance data from the X,Y location and the azimuth. With these two tool, a map was constructed for interpretation of the points and data that was gathered. Figures 3 and 4 are two different maps created from the data gathered during this activity.

Fig. 3 diameter of tree points collected based off of the attribute data.

 

Fig. 4 different species of trees collected.

Conclusion-

    The purpose of this lab was to expand knowledge in a scenario when a GPS or ground station stops working. An easy and fast remedy would be to use azimuth to collect points of interest. It is always smart to have a backup plan before going into the field and conducting an activity. Technology is not always reliable, as this lab would prove, but if one has a backup plan that works they would be prepared for any situation.