Distance and Azimuth Surverying

Conducting a distance Azimuth survey

Introduction: surveying with a grid based coordinate system is good on small plots but it is not ideal for many geographic circumstances. These days you can use GPS technology along with survey stations but sometimes you cannot rely on technology to come through. This is why distance and azimuth can come into play. It is a very basic technique that can work on many different conditions that can rely on sampling techniques and point quarter method. This allows us to map out linear features on a landscape from a singular point based on the azimuth of where the point was taken using the tools in ArcGIS such bearing distance to line command and feature vertices to points command. In this exercise we looked at the tree density in Putnam Park.

Azimuth Surveying in quadrants from Origin

Study Area:

The area of study for this assignment is the Putnam park area of the University of Eau Claire. In this area are new and old trees that have been planted on the grounds of the University of Eau Claire. This area is a good step for Azimuth surveying as it allows for a variety of tree species to be mapped with differing diversity and density. We will be collecting 10-20 point-quarter data collection of these locations from a centralized location that will not change.

Survey Area: Putnam Park 

Methods:

The first step in Azimuth surveying is to do the research of azimuth surveying. Azimuth surveying is an angular measurement in a spherical coordinate system that looks at the vector from an origin point which is then projected onto a reference plane. The angle between the projected vector and the reference vector is called the azimuth. An example is the North Star. The origin point can be the person looking at the point and the azimuth would be the angle between the North Star, the surface of the ground and the perpendicular projection of the ground. This can then be measured in degrees and can then be used in mapping. This is an older style of mapping without the use of relying on technology.

 Although we still rely on the technology in the form of the True Pulse 360 B.

Once we have the 360 B true pulse set up in an origin point in Putnam Park it is time to begin to take points. We are looking at trees and the azimuth of the trees as well as the distance from the point. To collect the distance we will be using a laser pathfinder and will relay the information back to the True Pulse system. This will allow use to laser designate the distance between the origin point and the point that we are collecting, this means we only have to use one latitude and longitude point which will be the origin station.

True Pulse 360 B 

After the points are collected it is time to import the data into an excel spreadsheet. The XY will be the same for all the points right now. When we enter the excel table we are adding in the diameter the azimuth, distance and tree type. From here we connect the excel table to the blank map in arcgis.

We will then convert the excel table to a usable format in arc catalog by adding the data into a geodatabase which we can then use the xy table from the excel sheet and create a point based on the xy data. It is important to mark the xy table correctly otherwise the next tools will not work. When the data was imported into excel the xy data was flipped so the Y coordinates were actually the X coordinates and the X coordinates were the Y coordinates. This meant that the data could not be used until it was corrected.

XY Data

Once this data is converted into a single point we can then run the tool bearing distance to Line command in the features tool set which creates a new feature class containing the geodetic line features constructed based on the values in a xy coordinate field as well as the distance field of the table. This will create only lines from the origin point. It is important to note that since this is a broad service WGS 1984 coordinate system needs to be utilized to make accurate readings.

Since the Bearing Distance to Line Command only creates lines from the origin point we will have to use the Feature Vertices to Points command in the features tool set to create actual points at the end of the lines. This will allow us to use the data that we collected by creating a feature class generated from the vertices of the lines. In essence it will create point data at the end of our line data.

Results:

The results of using Azimuth surveying are extremely accurate. This is a useful tool that is still in use today. It allows highly accurate data to be accumulated and does not rely on GPS or other highly advanced technology. This means that because the technology is not present it has a higher risk of not failing. The results from this azimuth survey are impressive and show that from a single origin point we can collect data that can be used for a multitude of purposes including road surveys, tree surveying and logging expeditions.

Conclusions:

Because technology can sometimes be a hindrance in field work it is important to rely on older more trusted methods like Azimuth surveying. If data needs to be collected in heavy foliage which would normally interfere with GPS systems Azimuth surveying could be used instead to create accurate maps. This is why Azimuth mapping is still used heavily for surveying work such as road construction and tree surveying.