Lab 1 : Survey of Terrain Surface

• Introduction
• In this first lab the class was broken down into groups that would create a terrain surface in the snow to be surveyed through a sampling technique to gather points that could later be transformed into a 3d map and to gain a basic understanding of common sampling techniques over a landscape. Sampling is a way to gather information in a fair manner on a smaller amount of a whole area being studied to answer questions. There are three main types of sampling methods:

• Random - sample points generated in an unbiased manner
• Systematic - sample points selected by measurements
• Stratified - selected areas with either random or systematic techniques applied
• Methods
• A systematic sampling technique was chosen to maximize the ultimate number of fairly distributed sample points. This method was chosen by the group because it was thought to best way to take the most accurate samples in particular lab. The location of the created landscape was in a planter box in the  back courtyard of Phillips science hall at the University of Wisconsin Eau Claire, USA on January 29^th at 2:30 pm. The materials used in this lab  consisted of strings, pins, measuring tape, yard sticks, a clip board, pen, paper and Microsoft Excel. The spacing determined for the sampling was done every 8 centimeters on a y and x axis. The plot the created landscape was in was 112 cm wide by 88 cm tall. A grid was made using the strings and  pins after being measured out as accurately as possible.(see figure 1.)

Figure 1. The created terrain and string measurements

• The group also decided to have the height of the planter box to be the zero elevation level. And simple method was chosen for recording the data. Using X Y and Z columns with each sample points measurement on the grid combined with its height, Z and was entered into Excel.

Figure 2. Group members taking measurements of landscape

• Results/Discussion


• The total number of samples recorded was 181. Out of those 181 samples, the minimum z value was -10 while the highest value was 19.5 with a mean of -.5. While we used a systematic sampling method, the other considered method was stratified-systematic but the group found that systematic was the best option to complete the objective to cover the whole terrain equally. Originally the plan was to survey an extended length as a 112 by 112 cm block but cold weather and an approaching sunset lead to a group decision in cutting back 3 sample rows at the edge of the landscape since they were thought to contribute little to the overall project since it was the drop off edge of the ridge. ONly running into mainly two issues, the first problem the group ran into was in the ability to construct or modify our landscape. The weather in the day prior melted the majority of the snow and with a cold night it was frozen and un-formable. Therefore the group had to use a previously formed landscape by another group. The second was how to as accurately as possible measure the frozen landscape features above the zero elevation. After digging through the box of available materials provided for this lab and trying several different methods. The chosen was to measure the height of the feature from its base and subtract the difference between that and the distance from the zero elevation.

Figure 3. Group members measuring out 8cm for systematic sampling method

• Conclusion


• The sampling done in this lab worked out well and represented the landscape as a whole. Sampling in spatial areas can be a good way to visualize boundaries, groupings and can show how dynamic an area is in a whole. While this was on a very small can it can display how sampling larger areas can work and issues that can arise with it and how to select a good sampling method based on your objective. Overall the survey performed did a good job of sampling the area.