The first lab assignment required the creation of a Digital Elevation Model of various features created in a wooden flower box with the use of snow as the medium. Very little guidance was given in order to create an atmosphere of critical thinking and hands on learning through trial and error. To create an elevation model, certain parameters needed to be met, such as the creation of a ridge, valley, hill, depression, and plain in the snow, as well as determining what coordinate system to use. The use of the coordinate system allowed for the collection of precise X and Y locations that contained a Z (elevation) value within the study area, which would then be used to replicate the landscape features in a 3D model in the second part of this lab activity.
Methods
The first step was to determine at what point on the box we would institute sea level. The final consensus was to build up and down from the midway point of the box with the sea level being the top of the box which would in turn make all of the collected elevation points negative values. Next, the actual features (ridge, valley, hill, depression, and plain) needed to be constructed in the snow.
Once the features were created, a coordinate system was created using string that ran across 100cm lengthwise and widthwise of the box. The string created a square grid with an x and y point at every 10cm interval. The elevation was taken at each point where the strings intersected.
Each measurement (x,y,z) was recorded in a notebook and then transferred into excel (Table 1).
| 100 | 15.00 | 14.00 | 15.00 | 15.00 | 14.00 | 13.00 | 14.00 | 13.00 | 12.00 | 10.00 |
| 90 | 16.00 | 15.00 | 10.00 | 11.00 | 10.00 | 7.00 | 9.00 | 7.00 | 10.00 | 7.00 |
| 80 | 17.00 | 15.00 | 20.00 | 23.00 | 22.00 | 22.00 | 15.00 | 14.00 | 19.00 | 15.00 |
| 70 | 3.00 | 23.00 | 7.00 | 10.00 | 13.00 | 12.00 | 10.00 | 18.00 | 12.00 | 7.00 |
| 60 | 12.00 | 5.00 | 13.00 | 5.00 | 13.00 | 12.00 | 15.00 | 12.00 | 11.00 | 12.00 |
| 50 | 15.00 | 20.00 | 15.00 | 4.00 | 12.00 | 13.00 | 15.00 | 14.00 | 10.00 | 10.00 |
| 40 | 15.00 | 15.00 | 14.00 | 3.00 | 11.00 | 12.00 | 13.00 | 7.00 | 3.00 | 1.00 |
| 30 | 15.00 | 15.00 | 15.00 | 3.00 | 11.00 | 10.00 | 10.00 | 5.00 | 0.00 | 0.00 |
| 20 | 15.00 | 15.00 | 13.00 | 2.00 | 12.00 | 10.00 | 10.00 | 5.00 | 0.00 | 0.00 |
| 10 | 15.00 | 13.00 | 12.00 | 1.00 | 9.00 | 10.00 | 9.00 | 3.00 | 0.00 | 0.00 |
| 10 | 20 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 |
Discussion
This field lab assignment required the use of critical thinking skills as well as group collaboration. The project went well overall. We were able to successfully construct our own coordinate system and determine where place our zero values. We did run into a few roadblocks along the way, most notably dealing with where our sea level (z-value of 0cm) should be. Attempts were made at filling the box with snow and building up/down from the top of the box but it was difficult to keep the string straight over at our 10cm increments over some of the features that were above the top of the box. Then we tried to remove half of the snow and make a level surface at the point where the two boards met--two boards were placed on top of each other to give the flower box its height--which was roughly 13.5cm. We were originally going to make that halfway point be our sea level but then decided to make the top of the box our sea level with each value essentially being negative. It would not be difficult to in turn make the halfway point our sea level, with 13.5cm being added to each z-value recorded. We also had trouble deciding how large to make the grid squares. We ended up using 10cm/10cm squares, which looking back on the project did provide a consistent scale but did not provide an accurate enough scale. Using smaller increments would make a more detailed and accurate depiction of the study area.
Conclusion
This lab assignment did in fact help to develop a better understanding on how to create coordinate systems and elevation models. We were left to figure out how to lay out our study area and how to collect data, with very little guidance or background on the matter. This helped us strengthen our critical thinking skills, ability to work in groups, and ability to creatively problem solve to successfully complete a new task.
