Lab 9: Distance Azimuth Survey

Introduction:
             Technology has helped science advance, helped people be able to record data faster, more accurate and to answer many more intricate questions. GPS and superbly accurate survey stations are typically used these days but as many of us know, technology can’t always be relied on and whether you’re on the job or working on a school project the task at hand still needs to be completed. For this week’s lab the class focused on an older data collection survey method called Distance-Azimuth. This method uses one pin-point location where the data is recorded and the object(s) being documented is surveyed by calculating the distance of the object(s) from the point. This way a slightly less accurate survey of an area can still be performed to document where things are and the attributes associated with them. For this lab the surveying centered around trees near the Little Niagara stream running through the University of Wisconsin-Eau Claire’s campus. The data collected for the trees were its species and diameter at chest height along with its azimuthal direction to the selected Lat/Long point at 44' 47" 50.99*  91' 30" 1* near a small bridge over the stream between the Phillips Science Hall and the Davies Center of lower campus. Below in Figure 1.  is a small map of the selected point’s location. Data for 17 trees was recorded facing the Phillips Science Hall. This activity was performed as a class before returning to the computer lab to create maps from the data collected.

Figure 1. Showing the location selected for data recordation.

Methodology:

Figure 2. image of the True Shot 360

            To complete this distance-azimuth survey a True Shot 360 range laser, seen in Figure 2. was used to gather the distance in feet and the azimuthal direction of the tree from the selected point. Figure 3. Is an image of the scope view of the True Shot 360. Not much preparation was needed for this activity other than bringing along the devices, measuring tape and a pen and paper to record the data, the class and Dr. Hupy left the classroom around 3:30pm on Tuesday April 5^th and selected a data recordation point at 44' 47" 50.99*  91' 30" 1* as seen in Figure 1. While the survey was taking place it was lightly raining and was about 36 degrees Fahrenheit. The class was put into groups of two to either record the species and diameter of the tree, read the distance, azimuth or record the data

Figure 3. Scope view of the True Shot 360

being gathered. The trees were recorded from closet and to the left of the selected point facing the Phillips Science Hall to the farthest and to the right on each side of the stream, although the last three trees were originally skipped over four trees prior, they were added at the end. Each two person buddy group took turns measuring the diameters of the trees at chest height with measuring tape while Dr. Hupy identified each tree species. The information was shouted back to the rest of the class standing around the selected point while other students were announcing the distance and azimuthal direction of the trees. In order to calculate the distance the True Shot 360 had to face its second half held by one of the students with Dr. Hupy against the tree. Each half needed to face the other for the True Shot 360 to calculate the distance between them. After recording 17 tree’s species, distance, diameter and azimuthal direction around the Little Niagara stream the class reconvened in the computer lab. There the recorded data was inputted into an excel file by one of the students and shared with the class in a temporary all access folder (See Figure 4.).

Figure 4. Class shared Excel file.

 After having all the data on an excel file it was formatted for the finicky Esri ArcMap by ensuring each number field was listed as a number field, no extra or unneeded data was left on the file, the longitude column was made negative (as we are west of the prime meridian) and that the data recordation point’s location was converted to decimal degrees from its original degrees, minutes and seconds by simply dividing the minutes by 60 (See Figure 5.).

Figure 5. Formatted Excel file

 In ArcCatalog a file geodatabase was created (along with a feature class) in this lab’s specific folder where the file was then imported as a table (See Figure). Then in ArcMap from the catalog window the geodatabase with the table was added. At this stage the data is shown as the single point. To display the distance associated with each tree the Bearing Distance to Line command or tool, located in the Features section of the Data Management folder in the ArcToolbox must be applied (See Figure 6).

Figure 6. Commands used from ArcToolbox

 Then in order to add corresponding points to the locations of the trees at the end of these distances another tool is applied, the Feature Vertices to Points command which was found using the search tab above catalog to the right of the screen in ArcMap. It can also be found in the ToolBox under the Features section of the Data Management folder like the previous tool (See Figures 7. & 8.). Then a detailed topographic base map was chosen rather than an outdated satellite image taken before construction and relocation of the Davies Center.  Finally an additional map was created showing the diameter and species of each recorded tree (Shown in Figure below in the Results section).

Figure 8. Result of Vertices to Points command

Figure 7. Result of Bearing Distance to Line command 

Results:
      Two maps were created from the recorded data. Figure 9. below shows the various identified species of the trees around the Little Niagara stream on lower campus of UWEC. 11 different species were recorded.

Figure 9. Species of recorded trees.

     The second map (See Figure 10.) visualizes the diameter at breast height of each of the trees in inches. As far as the complications encountered during this lab the rain soaking most of the class and their notebooks for recording the data was the first. Although thankfully a waterproof field notebook from Dr. Jol (another professor in the Geography department) and a pencil allowed for a mess free recordation of the data, whilst other students pages turned to mush and their pen ink smeared all over the pages. While the pencil worked out this time, it is a bad habit to takes notes in pencil as it has the ability to be erased and rewritten suggesting that data could have been changed after the fact. Most of the issues and frustrations of this lab happened due to instructions being different as the weather prevented an additional survey method, Point-quarter surveying, and an insane amount of glitching on the computer while in ArcMap. Only 2 issues with the data, the first seemed to be the azimuthal directions. Clearly the trees in the maps above were not in the building or stream but their exact locations skewed. This could have been from incorrect data stated or due to interference of the building, Phillips Science Hall. The "fan" as it could be described would need to be compressed vertically produce a more accurate representation. The second issue, a simple one, was that the diameters of the trees were recorded at breast height which was only an issue because the students took turns measuring the trees diameters at each their own breast height. This could easily be fixed by having one person gather this data but as this was a lab, each student needed a chance to be involved and understand the survey method being used.

Figure 10. Measurement of tree diameters at breast height.

Conclusion:
     All in all this was a beneficial lab showing the importance of simpler survey methods. In situations where higher grade technology may fail or none is or can be present this method can provide good data recordation and effectiveness.