Figure 1: A Trimble Juno with ArcPad software, used for data collection
Throughout the semester, we have had several activities held at the Priory in Eau Claire, Wisconsin, a piece of property acquired by UWEC that is
being used as the daycare center that was formerly located in the old
education building on campus. A tour of the location can be seen by
viewing the video on the right. In addition to the physical building on
site, which used to be a
monastery, an extensive nature area exists, which served as the location
to be test the accuracy of our maps.. With each visit came an increase in our familiarity of the area, features in the environment, and other things that come with repeated exploration of a new place. Using this knowledge, we were tasked with mapping features at the Priory by using a Trimble Juno, seen in Figure 1. In order to accurately do this, a geodatabase needed to be built, containing the features to be collected. From there, the geodatabase would be deployed to the Juno unit, and the data collection could take place. Once accomplished, the data would then be exported into ArcGIS 10.1 for manipulation. The collection of this data by each group can then be used in clean-up projects that desperately need to be done at the Priory. This blog post will detail the process of doing this, and demonstrate the result of the data collection.
Methodology:
Figure 2: A TruPulse Laser, used to gather height, distance, and azimuth values
For our specified features to be mapped, our group decided to map dead trees, standing and fallen. Two features classes were created in a geodatabase with a variety of fields needed for each one, and then projected in NAD 1983 HARN Wisconsin TM coordinate system. Our group was interested in height, trunk diameter, woodpecker use, fungal presense, decomposition and placement of the trunk of the fallen trees, and leaf type of the standing trees. Each field was added to the appropriate feature class, and then domains and subtypes were attached to each of the fields. Domains and subtypes allow for a sort of feature class within a feature class function in which each field has a set of choices associated with it. For instance, the decomposition field was broken into three categories, 1 being light, 2 being medium, and 3 being heavy decomposition. Adding these domains and subtypes allowed for the user to select one of the numbers, instead of manually entering 'light', 'medium', or 'heavy', saving a considerable amount of time. .The last step was to add a base layer to serve as a reference point on the map that was going to be displayed on the Juno. The Eau Claire West, Southeast Quadrant aerial photo was used for this purpose, providing a good deal of detail on the Priory and the surrounding area. The geodatabase, complete with features and base layer, was then imported into ArcMap and saved as a map document. By using the ArcPad Data Manager, the features and basemap were then transferred to the Trimble Juno to be used in the field. Data collection consisted of getting GPS points by standing near the tree, measuring the trunk diameter by using a tape measure, and getting tree height and azimuth values of fallen trees by using a TruPulse laser, seen in Figure 2.
Figure 3: Bearing Distance to Line tool used in the activity
After data collection, the collected features were then imported into ArcMap for manipulation. Having the geodatabase set up made this very simple, with the only real task that needed to be done was finding the X and Y coordinates of the fallen trees to run the Bearing Distance To Line tool. This was done by adding X and Y fields to the Fallen Tree feature class, and then using the distance values provided in ArcMap to add the appropriate values for the corresponding tree. Using these values, and the length and azimuth fields recorded by the TruPulse, the Bearing Distance to Line tool, seen in Figure 3, could then be used to compute the size of the fallen tree and its direction on the ground, as seen in Figure 4.
Figure 4: Output of the Bearing Distance to Line tool, showing the direction of the trunk of the fallen tree
Discussion:
Using the data collected, a number of maps were able to be created demonstrating the various characteristics of the trees examines. Figures 5 and 6 show the presence or absence of fungus growing on the dead trees. Figure 7 displays if the trees that were still standing had evidence of woodpecker use, as dead trees are popular nesting sights for woodpeckers. Figure 8 demonstrates the decomposition level of the fallen trees, with 1 being light, 2 being moderate, and 3 being heavy. And finally, Figure 9 shows the leaf type of the standing tree, either coniferous or deciduous. With the exception of one tree, all of the trees examined were deciduous. These maps can be used to investigate subjects like woodpecker habitat in the woods surrounding the Priory, or for determining the location of fallen trees and positioning of the logs for cleaning up the grounds.
Figure 5: Fungal presence of dead trees
Figure 6: Fungal presence of fallen dead trees
Figure 7: Woodpecker use of standing dead trees
Figure 8: Decomposition levels of fallen dead trees
Figure 9: Leaf types of the fallen trees
Conclusion:
This activity was another great exercise in preparing for a field exercise. Having to sit down and plan out the various fields that each feature class completely organized an otherwise chaotic experience. Having each field that we were interested in included in the geodatabase told us exactly what we wanted to examine while in the field, allowing us to start collecting data as soon as we got to the site. Ensuring that the ArcPad file worked prior to going out in the field was extremely important to the process, as this also allowed for immediate data collection. Knowing that the program was going to work exactly as it was designed to was a great feeling, as that would be one thing that would not have to be fixed in the field. All of this preparation led to a straightforward data collection with no real issues. While these maps are by no means a comprehensive list of all of the dead trees at the Priory, the database can be expanded at any time to include all of the trees if that was something that was determined to have importance. Having experience with both the Trimble Juno and the TruPulse laser certainly helped with the process as well, cutting down on the learning curve and allowing us to smoothly collect the values we needed in order to get the desired data.
A significant section of this course in geographic field methods has been that of balloon mapping, an inexpensive way to obtain fairly high quality imagery of the earth that can be used to provide more up to date images to detail areas where recent satellite imagery has not been taken, specifically the University of Wisconsin Eau Claire campus. A previous blog post detailed the use of a balloon mapping rig, using a Panasonic Lumix eight-megapixel camera on continuous-shot mode, and incorporated those images to
create a mosaic of campus, using the software programs MapKnitter and ArcGIS. This is not the only use for a balloon mapping project, however. In addition to the tethered balloon, the rig can be let go and fly into the sky, equipped with a tracking beacon and insulation to keep the camera from freezing up at high altitudes. This blog will detail the processes involved in the flight of the HABL, and the subsequent recovery and post-processing imagery that was obtained through the flight.
Methodology:
Figure 1: Construction of the mapping rig.
Figure 2: Taking the fully inflated balloon to be released
The most important part about preparing for this activity was the construction of the HABL rig itself, which was done mostly in Lab 3. Taking a styrofoam container and modifying the lid so that the FlipCam could point its lens downward in the right direction was important to produce quality images that would be clear, despite the high winds that day. This was done by securely attaching the FlipCam to the lid by using Velcro pads, with the final product seen in Figure 1. Teamwork was a critical step in getting the camera packed
into the rig and getting the rig secured to the balloon.
The materials inside of the rig included a waterproof case
for the camera with hand-warmers packed around it to prevent freezing at high
altitudes, and a GPS tracker to allow for recovery of the unit. The rig was
hung from rope on each of the four corners; about 3 ft. in length, and then the
pieces are tied together at the top so that the carriage can swing in flight.
Pieces of packaging tape were used to secure the lid on the bottom of the rig,
so that the camera would not fall out during the course of the flight. The
camera carriage was fastened to the balloon by a series of carabiners.. With
the rig already built, the only real preparation that needed to be done on the
day of launch was to fill up the balloon to be used. This balloon was
significantly bigger than the one used in the previous balloon mapping
activities, and made of stronger latex to withstand the amount of pressure that
would be bearing down on it as the balloon gained altitude. The balloon was 8
feet in diameter, roughly 3 feet larger than the first one, with the sheer size
of it visible in Figure 2. Being bigger meant that more helium would be
required to fill it up, taking approximately one hour to fill the balloon up
fully and ensure that the mapping rig was securely fastened. We did not want to
fill it to the max as the balloon would need room to expand as it rises, so it
was not fully inflated for this particular activity. Once the balloon was
filled to the desired level, the neck of the balloon was secured with a few zip
ties and then folded it over, using a liberal amount of duct tape to ensure
that the balloon was closed up. The camera carriage and parachute were then
fastened and the rig itself was then ready to fly.
Discussion:
It was roughly two hours when we found out that the balloon had landed in Spencer, WI, with the path of the balloon being visible in Figure 3. The balloon had actually landed in a tree, seen in Figure 4, on a private landowner's property. Negotiations were held to allow us to go on the recovery mission to get mapping rig. After consent was given, the tracking device was followed to lead the retrievers to the selected tree where the parachute had delivered the remains of the balloon and the mapping rig.
Figure 3: Map showing the path of the balloon rig
Figure 4: The tree in which the HABL rig was found in Spencer, WI, close to 80 miles away from Eau Claire.
Figure 5: Recovery of the balloon, parachute, and mapping rig.
The entire apparatus was in surprisingly good condition, as demonstrated in the picture in Figure 5. After recovery, the process of getting the data off of the camera could finally be done, and we could then see just what kind of imagery we had collected throughout the course of the balloon's 78 mile flight. Figures 6, 7, and 8 show some frames of the video shot with the camera, in fairly good quality imagery. Haas Fine Arts Center on the UWEC campus is clearly visible in Figure 6, and the same goes with the higher altitude image of the Chippewa River in Figure 7. The balloon eventually got high enough so that the curve of the earth was seen, visible in Figure 8. The video of the entire trip, which was limited to just under an hour due to the amount of memory on the FlipCam, can be seen just below Figure 8. The end of the video, where the flight starts at 7:24, is a little unstable, due the rig just being attached to the balloon by a string, and the winds bombarding the rig. It is the presence of this wind, however, that is the reason the shots of the curve of the Earth in Figure 8 can be visible at all.
Figure 6: Aerial footage of Haas Fine Arts Center, at the beginning of the HABL flight
Figure 7: Aerial image of the Chippewa River, seen from the balloon
Figure 8: Picture demonstrating how the rig captured the curve of the Earth
Conclusion:
The HABL launch was the conclusion of a nearly semester long process of trial and error in the balloon mapping field. Balloon mapping hasn't become widely used in the mainstream geography
community yet and we're already on the forefront of it at UW-Eau
Claire, demonstrating just how ahead of the curve we are. It is very unique that as undergraduate
students we can be a part of the small percentage of people who are
using this technique. The technical aspect of this course has given us the opportunity to be hands on with our education, and has given us a vested interest in seeing the success of our project. The teamwork aspect was critical, as this project would not have been completed without the input of the entire class. Delegation of responsibilities created manageable jobs for everybody involved, and covered all of the necessary aspects in preparation for the flight. Throughout the course, the importance of ensuring that all is done before going out in the field was stressed, and the conduct of our class throughout this activity exemplifies our understanding of this crucial step in the field methods process.
The article put out by the UWEC News Bureau for the HABL can be seen here.
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