Using ArcPad to Collect Field Data

Introduction

The final exercise of the semester involves collecting data using a mobile device. In this particular instance, a Trimble Juno GPS will be used in conjunction with ArcPad to collect field data at the Priory. We have spent a good amount of time this semester out at the Priory, which is a plot of land recently purchased by the University of Wisconsin - Eau Claire, which is now a daycare center. Other than the daycare center, the rest of the property is occupied by forest with ever changing topography. There are some trails evident but have not been properly kept up and the trails are poorly marked in spots.

Fig. 1 - Trimble Juno GPS used to collect the field data.

The goal of this assignment was to collect certain types of features at the Priory so that the data could be compiled into useful maps. Being able to understand and employ ArcPad in the field is a crucial asset as this has become a very popular way for companies to collect data in the field. After the data collection is complete, the data will be uploaded into ArcGIS where feature classes will be created and then overlaid on top of a high resolution aerial image.


Study Area

Fig. 2 - The Priory is approximately a 4 mile drive from the University of Wisconsin - Eau Claire campus.



Fig. 3 - Aerial photo of the Priory - Eau Claire, WI.

The total land area that this exercise will take place on is approximately 112 acres in size and consists of hilly and woody terrain.


Methodology

In order to efficiently complete the field work in a 3 hour time period, the class split up into 6 groups.

Fig. 4 - Groups and their respective members. 

 Some of the features that were assigned to different groups were: Trails (type, condition), Trail Markers (color, shape), Benches (condition, azimuth), Erosion Points, Fallen Trees (lying over trails), Animal Tracks, Birdhouses, and Garbage (piles of garbage or abandoned equipment). After each group knew what they would be mapping, we needed to setup a geodatabase in ArcMap. The geodatabase was named appropriately and assigned the coordinate system NAD_1983_HARN_Wisconsin_TM. Once the preliminary steps of creating the geodatabase was complete, we added two point feature classes to it: Benches and Markers. Since each feature class had different criteria possibilities, it was necessary to create fields and domains for each feature. For Benches, this meant including an Azimuth field ranging from 0-365, and a Condition field with options Good, Fair, and Poor to describe the bench's condition. For Markers, a field was created for Shape (no domain was set for this), Medium (wood, metal, or other), and Color (no domain was set for this either). The fields where no domain was set is because we were not sure how many different colors were used for trail markers or how many different shapes there were. Because of this, we did not want to limit our options by creating a domain. However, we could still be able to manually type in the text values on ArcPad in the field. The benefit of using domains is that defined values can be used to mitigate manual entry error.

After we had defined all of the conditions, it was time to export the geodatabase onto a Juno GPS unit. This can be done through the ArcPad Data Manager Toolbar.

Fig. 5 - The ArcPad Data Manager toolbar in ArcMap 10.1.

By clicking on the Get Data button, circled in red, the wizard takes you through the steps for getting the data ready for ArcPad. This involves defining the folder path to where the data will be stored. An ArcPad map project will be made with a .apm file extension. After this, the data will be deployed to the appropriate folder. The next step is to connect the Juno to the computer via USB cable. The deployment folder can then be pasted onto the SD card inside the Juno. It is best to check the Juno to make sure the process was completed properly before heading out to the field. So no we have the geodatabase containing the feature classes on the Juno as well as an aerial basemap which will run in the background. The basemap is optional as it is useful but can bog down the system.

Once we arrived at the Priory, all we needed to do was wait for a GPS signal lock and then we took to the woods to start collecting data. After a half hour of data collection, it was evident that with all of the trail markers on the trees, it would take more than our allotted class period to collect all of the data. We split the group up so that I would collect all of the triangle shaped trail markers, Kent would collect the circle shaped markers, and Beatriz would collect the benches. This proved to be a way more efficient way of collecting the data and we had it all collected within 2 hours. Once, the data collection was complete, we headed back to the computer lab to upload the data into ArcMap. A tool called Bearing Distance to Line was run on the Benches feature class in order to show the azimuth of the view from each bench. We did not collect data on the view distance from each bench so a standard 25m distance was given to each bench. The important thing here is that we can see which way the bench is positioned.

The data was saved on the Juno as an .ssf file which is not directly supported in ArcMap. In order to convert this to a shapefile, we had to employ the ArcPad Data Manager once again. This time, we clicked on the Add Data icon and uploaded the .ssf file. From there, it recognized our Benches and Markers features. We clicked both of them and then clicked the "Check in" button which updated our reference geodatabase with the new attribute data for our features.

Fig. 6 - Updating the geodatabase with feature point data collected with ArcPad.

Results/Discussion

Fig. 7 - Trail markers and benches at the Priory.

Fig. 8 - Zoomed in look at the trail markers and benches.

The first time employing an ArcPad project into the field was very successful. There were a few groups who lost their data in transition from the field to computer. We were lucky enough to retain all of our data. We were able to gather all of the data we originally set out to in the allotted time. We ended up with 51 trianle markers, 51 circle markers, and 6 benches. It looks like the benches are spread around the trails in a very even manner. It is a bit confusing determining what the triangle and circle markers differentiate. We only saw one sign indicating a trail name. Also, it was quite common to see a triangle marker on one side of the tree and a circle marker on the other side. Perhaps the different shapes indicate the direction of travel on the trail. Now that they are mapped, the coordinator at the Priory can clear up this confusion. We also entered attribute data for the condition of the markers as well indicating if they are clearly visible, need paint, or if they are on a fallen tree of which a few were.

Conclusion

This exercise was beneficial in two ways. First of all, we got invaluable experience with another component of ESRI software in ArcPad. This sort of skill is highly marketable as this is a very popular method in data collection. Secondly, the types of data and the detail it was collected in, both spatially and attribute, will help the coordinator at the Priory with improving the trail conditions. Maps containing multiple datasets can be made to allow visitors to navigate with ease and allow them to have an enjoyable time exploring the woods at the Priory.

High Altitude Balloon Launch (HABL)

Introduction

The objective this week was to launch our HABL rig into the upper atmosphere with a camera recording the journey. Typically, balloons such as these, reach altitudes of 60,000 to 120,000 ft which would be located in the stratosphere. The stratosphere is the second major layer of the Earth's atmosphere, sitting atop of the troposphere. The stratosphere is characterized by cool temperatures near the bottom and warmer temperatures higher up which is the direct opposite of the troposphere where the warmer air is located near the surface and cools as altitude increases. This is because the Earth's atmosphere is warmed from below from trapped radiation from the sun. This temperature inversion becomes important in regards to launching a balloon that high because the equipment (camera, GPS) will be exposed to very cold temperatures and thus need to be protected with insulation. Since helium is lighter than air, the balloon will rapidly ascend, expanding as it rises. Eventually the expansion of the gas inside the balloon will be so great that it will cause the balloon to burst. The ascent of the balloon can be controlled by how much helium is inside the balloon. Since the weather has been very inclement this spring, it was a gamble on when we could launch our rig. We finally got a nice day on Friday 4/26 with temperatures around 70°F and a slight wind which prompted us to launch the balloon.

Methodology

We had been preparing for this day on and off the past few months. Earlier on in the semester, we researched balloon types, weighed out a payload, and made a few rig designs so that we would be prepared for launch day. Around 8:30 a.m. on 4/26, some of the class arrived at school to fill the balloon with helium and to secure the parachute and camera rig to the balloon. The camera was placed in a square styrofoam container with a lens hole cut in the bottom in order to allow a clear area of view for recording.

Fig. 1 - The camera carriage being constructed.

 Hand warmers were shaken to activate the heat which would keep the camera from freezing up at high altitudes. A flip camera was used as the recording device which supports up to an hour of video recording. The rig is suspended from rope on each side, approximately 3 ft. length, and then the pieces are tied together at the top so that the carriage can swing freely in flight. Pieces of packaging tape were used to fasten the lid on the bottom so that the camera would not fall out during the course of the flight. The camera carriage was fastened to the balloon via carabiners. The balloon was larger than the one used for the aerial mapping exercises we performed over the last few weeks. It was necessary to get a larger balloon for this exercise as it would be required to obtain higher altitudes. The diameter of the balloon after filling it with helium exceeded 8 feet. We did not want to fill it to the max as the balloon would need room to expand as it rises. Once the balloon was filled to the desired level, we fastened the neck of the balloon with a few zip ties and then folded it over on itself and duct taped it liberally. A small GPS tracking device was also attached to the rig so that we would be able to locate the signal of where the rig lands. The camera carriage and parachute were then fastened and then we walked the HABL rig out to the center of campus to launch it.

Fig. 2 - Transporting the HABL rig to the launch pad.

Results/Discussion

With a wind around 12-15 mph from the west, the balloon took off rather quickly from the launch pad in an easterly direction. The balloon managed to gain altitude rather quickly as it was blown away. After a few minutes, we lost sight of it and headed back inside to await a signal from the tracking device. Over an hour passed before we finally got a signal from the tracking device telling us that the rig had landed in a field near Marshfield, WI which is a little over an hour away from where we launched it. There were some strong high level winds which carried the HABL a distance of 78 miles!  The complete video is posted below. The camera took an hour's worth of video and shut off shortly after the descent.

http://desi.uwec.edu/Geography/Hupyjp/Weather_Balloon_1024.asx (Here is a quick link until I can get the video embedded into the blog)

Fig. 3 - A still frame of a shot above the campus of UWEC.

Fig. 4 - The balloon has ascended quite high at this point as the field of view has increased dramatically.

Fig. 5 - The balloon close to its highest altitude taking an image off nadir allowing us to view the horizon.

Fig. 6 - This still frame is my favorite image. How awesome is it that the balloon reached this height and captured this awesome image! At this point the air is very thin and the balloon probably popped shortly after. 

Fig. 7 - The balloon got caught in the canopy of a tree 50 ft. off of the ground on its way back down to Earth. 

Fig. 8 - Professor Hupy recovers the camera carriage after free climbing the tree and sawing off the branch the rig was hung up on. 

Fig. 9 - The balloon started to travel in a northwest direction from the launch location as it passed over the U.S. 53 bypass.

Fig. 10 - The HABL rig is passing by Lake Eau Claire here, about 20 miles from the launch location and has since switched to a southeasterly direction of movement.

Fig. 11 - The HABL covered approximately 78 miles in its journey before landing in the country near Marshfield, WI.

Conclusion

This exercise was probably my favorite one this semester as it was awe-inspiring to see the results from the HABL flip camera. I have never even considered an opportunity where I could be a part of a project sending an object that high into the air and being able to recover video from it. Looking at the still frames from 100,000 ft. is just mind boggling. I wish that the camera rig had been more stable throughout the flight as it can be very nauseating to watch the video with everything spinning so fast. A popular idea on fixing camera stability on a balloon rig is that of a gyro-stabilized contraption so that the camera remains in a fixed position as the unit rotates with the balloon. This would be immensely helpful for the next launch as the video quality would be much improved and more still frames could be extracted. The other limitation of this launch was the camera being used. The Flip Cam could only record up to an hour of video which ended up cutting out much of the descent. A GoPro camera would be ideal for this sort of application as it is more rugged and can record for a much longer time as well as providing stunning video quality. These changes will require more money but would be well worth it as the end product would be that much better. A proposal has also been stated that for the next launch, there should be a camera taking video in the near infrared (NIR) to get satellite quality imagery. Also, a thermometer, barometer, and anemometer should be sent up with next time as well to collect temperature, pressure, and wind speeds at different altitudes to better understand the upper atmosphere. There are a lot of really cool and practical applications that this sort of project can be used for. The event was profiled by a local paper as well which can be read here: http://www.uwec.edu/News/releases/13/05/0507HABL.htm.