Creating a Terrain Surface

Introduction

     Many different geographic projects involve collecting survey data in the field. In this lab we created a 3D landscape in the snow, set up a coordinate system, and surveyed the area to collect elevation values across the landscape. Although this exercise was done on a very small scale, a similar approach can be used to create terrain surfaces of much larger landscapes.

Methods

     To begin this exercise, we created a 3 dimensional landscape in the planter boxes, measuring approximately 1.2 meters by 2.36 meters, in the courtyard of Phillips Hall. The landscape was required to contain a ridge, a hill, a depression, a valley, and a plain (Figure 1).

Figure 1  Planter box with the landscape created out of snow.

 

 

 

     Next, we set up a grid system to collect the elevation values. Since the area was fairly small and the landscape contained gradually changing features we set up a grid of 10 cm by 10 cm. This ensured a detailed terrain (Figure 2).

Figure 2  Coordinate system created with sting in 10 cm intervals.

 

 

     Since the edges of the planter box were higher than the landscape itself we set the datum to the height of the edges and measured down to the landscape to get elevation values (Figure 3). This led to negative elevation values (Figure 4).

Figure 3  Measuring the depth to the landscape from the datum (edge of the planter box).

 

 

Results

 

     Table 1 shows the elevation values that were measured from the top of the planter box. Since the landscape was below the datum all the elevation values are negative.

Table 1  Elevation values that were collected at each 10 cm interval.

Discussion

     Overall, our landscape was pretty flat with a few gradually changing formations. Since there was not a lot of complexity in the landscape we were able to use regular intervals of 10 cm to attain an accurate surface model. If the landscape had areas with significant elevation changes we would have had to increase the spatial resolution of the grid to collect more data points.

Conclusion

     In conclusion, this exercise provided a set of basic skills that will be the foundation for this class. It helped us think rationally about the task at hand and what was required before we actually went out into the field. This is very important in all field projects. If you can conceptualize the project before going into the field one can prepare for different problems they might come across, which will lead to better quality data.