Lab 1 Resurvey

Introduction

            With the same set of parameters used in the first survey of our target natural surface, we set out to further our understanding of terrain analysis by redoing the lab to account for and correct the many errors we experienced in our first survey.

Methods

            To survey the planter box assigned to us in the Phillips court yard a second time, we employed many of the same methods used the first time with slight modifications to account for error and accuracy. Using the same idea of a grid to system like the first time, we recreated a Cartesian coordinate system using string and thumbtacks but this time with a much higher resolution; instead of six inch by six inch pixel resolution, we now have eight by eight centimeter pixel resolution. Also, instead of using the highly inaccurate method of measuring down from the center of each pixel like we did in the first time to record each respective Z value, we instead took Z measurements at each intersecting X,Y coordinate. After recording all of the data longhand using pen and paper, we translated them into an excel spreadsheet and prepared the data to be displayed in Arc. Using the same corrective formula used the first time to reverse the theoretically negative Z values due to measuring down from the established “sea level” plain created by the physical coordinate system gridlines, we manipulated the data to mimic the target natural surface.

Discussion

            Again with all field work, there will always be unpredictable conditions that will be encountered. Much like our first survey, we experienced finger chilling temperatures that slowed down data collection due to us having to head inside to warm up every thirty or so minutes. As a group we agreed that the survey resolution in lab one was our biggest issue. To correct that, we surveyed using smaller pixels and took measurements at each intersecting X,Y coordinate which greatly increased our accuracy by doubling the number of data points in our survey. Although we modified many of our methods in the second run at this lab, I did notice we encountered a few of the same issues that we were unable to account for. Since we used fluffy, powdery snow to create our terrain surface, I noticed it was sometime hard to measure the exact Z value due to the fact that the ruler would sometimes sink down into the snow because it was difficult to hover right at the surface when measuring each Z value. To address that issue, we would have had to use a different, harder surface for our terrain such as dirt, or ice.

Conclusion

            After finishing our second run at this lab, a few conclusions and observations can be drawn. First, by doing this lab two times allowed us to not only gain a better understanding of terrain analysis, but also allowed us to evaluate or own performance, and correct any issues encountered the first time. The biggest thing I learned from this lab aside from how to survey a surface using very basic tools, was that by collaborating with a your team following a project on ways to adjust your methods to correct errors, you can greatly increase the value and accuracy the final product. I really liked that we had to go out and redo this lab because the output from each survey as displayed using Arc software is amazing. The difference between Lab one and Lab two is like night and day. See attached images as examples of this difference.