The first assignment for Geospatial Field Methods is to
create a landscape in the snow, build a coordinate system for the area, take
elevation points, and import said points into ArcMap or ArcScene to create 3D
interpretations of the target area. For the first week, and this blog post,
each group was to create their landscape and take their elevation points,
making sure to document their effort and explain their choice of method. In
week two, another blog post will contain the created 3D models and an in-depth
discussion of their effectiveness and our techniques effectiveness will follow.
At UWEC, the L.E. Phillips Science Hall contains
classrooms and offices for multiple departments, one of which being Geography.
In the center of this building is a courtyard in which food is grown, bee hives
are kept, and random class activities happen. There are multiple raised garden
beds in the middle of the Phillips courtyard and this is where each group
constructed their landscape. It was January/February in northwestern Wisconsin
so snow and cold weather was rather abundant. On a dry cold Saturday afternoon,
Group #2 met in the Phillips courtyard and began construction.
METHODS
The top of the raised bed was deemed sea level and
features were built up over the top and dug down into the box. The packing and
removal of snow was done by hand. Once the landscape was made, 8cm sections
were measured along all sides of the box and a piece of string was placed at
each mark. Placing string from one side of the box to the other formed a grid
of 8x8cm squares draped on top of the landscape.
Figure 1: The raised garden bed before the landscape was constructed. The snow was dug out first so the group could decide which method would be best. There was not much room in the box to make features if the coordinate system was to lay straight across the top of the box. Therefore, it was decided to use the top of the box as sea level and build the features accordingly.
Figure 2: Once the 8x8cm squares were measured, string was draped over the landscape to act as a coordinate grid. By using this method, distortion of the grid was inevitable but allowed for less eye strain and inaccuracy when reading the meter stick to gather elevation data later on.
Figure 3: The finished lanscape and coordinate system. With everything built, measurements could now be taken. The group split into two pairs and began taking points at different ends of the box, being careful not to move the loose string ends in the process.
Once the landscape was formed
and the coordinate system was in place, elevation data could be collected. One
person used two meter sticks to measure the middle of each square and the
number was recorded by a second person via paper and pencil. To determine the
height of each square, a meter stick was placed vertically at sea level and
another meter stick was placed horizontally at the middle of each square. Where
the two meter sticks crossed is what elevation was given to the square. The
samples of elevation data taken were equally spaced throughout the landscape.
DISCUSSION
There were many ways to complete the task of mapping out
the snow landscape because very little direction was given. The point of this
exercise was to make students use their critical thinking skills to come up
with a method they deemed reasonable. The first decision that needed to be made
was how the landscape should be built in relation to a coordinate system.
Should the landscape be built up over the box, allowing for large features and
easier measurements but a less accurate coordinate system, or dug into the box,
allowing for a more accurate coordinate system but much smaller features which
may lead to difficulty in taking measurements?
Opting for larger features and easier measurements, Group
#2 started constructing mountains, a ridge, a river valley, plains, and a lake
depression. Once the landscape was built, the coordinate system began to take
form. Eight by eight centimeter sections were measured to allow for enough
precision without getting bogged down with too much data. By stretching string
across the box to act like a grid, measurements could be easily recorded on a piece
of paper with a similar grid. Because the top of the raised garden bed was
deemed sea level, the mountains and ridge protruded out over the top of the box
slightly distorting the coordinate system because the string ended up draping
on top of the features, which was a calculated risk taken earlier when construction
began.
Elevation points were taken in every square which
resulted in an even spacing of samples throughout the entire landscape. This measurement
method could be slightly improved by taking samples at the intersections of the
strings allowing for more measurements to be taken at intervals between the
strings for areas of steep slope. Some squares had drastic changes in elevation
and deciding where to take one sample per section became difficult. Another measurement
problem encountered was getting the meter stick held vertically to stay at sea
level and not dig down into the snow giving false elevation readings. A
possible fix for this would have been to spray areas at sea level with water to
freeze the surface. Taking measurements of the feature’s elevations turned out
to be more difficult than expected.
CONCLUSION
The method taken to build the landscape and measure the
feature’s elevations was less time consuming than thought but may have resulted
in poorer results. With only one sample measurement per square, the models made
later may not be as accurate as they could be. Building smaller features below
a string gird may have produced better results, especially since the method
used was chosen to minimize measurement difficulty but once applied to the
landscape ended up having its own fair share of problems. The elevation data collected could now be entered into an excel worksheet and imported in ArcScene to make different 3D models of the landscape. These models will be shown and discussed in next weeks post.
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