Monday, May 13, 2013

Monday, May 13: Handheld GPS


Introduction:
                This semester’s last exercise will be based on digitization of real world features with a handheld GPS unit. For it, we will be returning to the Priory and dividing into groups of three that will navigate the land in order to collect field data from three different categories of information.  This is the same property that has been traversed by the class four times over the course of the semester, and from experience we know that it has a number of trails crisscrossing well over one hundred acres of wooded hills. 


Figure 1: The Priory


               The goal of this project is to prepare and deploy a geodatabase which employs domains and ranges to assist in data collection, then after collecting the data to import the information found into a GIS and display a professional-level map of what was found in the field.  Furthermore, information that was considered of potential importance to the project was determined and collected with the location of material collected in the GPS.  The trio in which I was digitizing data selected benches, erosion, and the invasive species buckthorn to collect and analyze data from.

 Methodology:
                The first task in our final adventure is to develop a geodatabase that can be deployed to a mobile GPS unit for data collection.  For this, the typical steps in developing a geodatabase in ArcMap were followed (as outlines in earlier posts), along with the creation of a point feature class for benches, erosion, and invasive species.  For each, domains were developed and included in the geodatabase in order to improve and speed data collection.  For bench data, the quality or condition of the bench was included (as useable, useable but needs repair, or unusable).  With the invasive species of buckthorn as well as erosion, the amount encountered was included in the data collection as well (low, medium, high).  Finally, a notes field was included to each feature class to provide an outlet that could record any unforeseen but still important or useable data collection.
fig 2: Creating a Domain

fig 3: Setting a domain in a feature class

                After developing these domains, the ArcPad Data Manager Extension was used to import this geodatabase to the chosen GPS unit.  In addition to returning to the Priory for this project, the final installment of our field methods class includes the return of the Trimble Juno handheld GPS unit (fig 4) which was what the database was uploaded to before heading into the field.  This process was simplified by the “Get Data for Arc Pad” wizard, activated by clicking the “Get Data for Arc Pad” button on the ArcPad toolbar (fig 5).  This program helps guide a user through selection of which data to export to the Juno, along with photograph options for feature classes and output options and extraction criteria.

fig 4: the JUNO

                Data collection was a fairly straight forward process:  our group simply set out a path which trekked through the priory following a major foot path and digitized the locations of our selected features as we encountered them.  Being that none of the selected features were continuous, each individual group member decided to collect each feature in the event of problems arising with the data collected by one (or two) of the group members.
figure 5: the ArcPad toolbar
First button with arrow is to deploy to a GPS, button with left arrow is to import from 

Finally, once satisfied with the data collected it was returned to the GIS and prepared into a map that displayed the data collected by feature.  The importing was also done through a wizard accessed from the tool bar called “Get Data from ArcPad” (fig 3).  Esri doesn’t fool around with the names for their tools, which is nice because it makes them easier to use.   After completing the steps outlined by this program (which merely consist of selecting the data to upload onto the computer), the data was successfully imported and manipulated into a useable map.

 Results:
fig 6: the Final Product

The first takeaway that I had from this exercise, and the first bit of advice that I have for any trying to recreate it, is to know your technology.  Twice the technology failed my group in this exercise, first in my attempts to upload my database to a GPS unit that was known to be faulty (unbeknownst to myself), and again when my team member Joey was mysteriously unable to acquire a satellite fix with his Juno unit.  Countless minutes of my life were washed away in a futile effort to do something that would not ultimately be done, and an opportunity to gather data was similarly wasted by the technology failing to work.  I could not help but appreciate the irony that the final project done in this class harkened back to one of the very first lessons imparted on us by professor Hupy: don’t trust technology, if it can fail, it will and often at the worst possible times.  Fortunately, Brandon and I had also been collecting data that would otherwise have been Joey’s domain, and the group successfully completed the task of mapping three different features at the Priory.

Another takeaway would be that the handheld GPS is not always the most accurate data collection unit, especially when the sky is obscured by trees.  While much of the data collected by Brandon and myself matched closely, some simply did not and this combined with the earlier paragraph is a lesson in the limitation of GPS data and a reminder about the importance of knowing how much you are willing to trust the data given to you.

Monday, April 29: High Altitude Balloon Launch


Introduction:

Today’s exercise is the culmination of the previous several weeks spent working on balloon mapping and aerial rigs, etc.  Today, we will fly.  We will soar.  We will launch the University of Wisconsin- Eau Claire into space.  Having finally perfected our camera apparatus and being that the weather appears cooperative, on Friday, April 26 of 2013 the class rigged our space platform to our weather balloon and said our prayers as we floated our helium-powered remote sensor 60,000 feet into the stratosphere.  Hopefully, the camera will parachute safely back to us and we can recover some interesting imagery from our High Altitude Balloon Launch.

 

fig 1: Launch


Methodology:

As can be found in previous posts, this project is something that the Field Methods class has been preparing some time for.  More information can be found in the post for Monday, Feb 11 but I will recap the section that pertains to the HABL.  This activity will take a camera into the upper section of the Earth’s atmosphere, so if we desire to recover any data from the activity we will need to take precautions that combat certain elements of that region of the planet.  Our camera rig will need to

1)      remain attached to the balloon

2)      hold a camera, parachute, and GPS tracking device

3)      deploy the parachute effectively when falling

4)      be light enough that the balloon can rise with it

5)      be stable enough that the camera it contains will capture serviceable imagery

6)      insulate the electronic components enough that the extreme cold, heat, and low pressure of the upper atmosphere does not do any damage to them nor will impact with the earth

7)      be waterproof

  
The rig was based around a Styrofoam outer shell built from a modified tackle container.  A hole was cut in the bottom and plexiglass cover fitted so that the camera could take images through it.  The camera itself was set to take video from this porthole, it was expected that the camera would support an hour of video recording and that the launch would require about forty five minutes to reach its maximum height.  Also included in the rig was a GPS tracking device that Prof. Hupy had effectively rigged to his iPad.  During the launch, this would quickly stop being tracked as its distance from eath’s surface expanded, however it did send out a couple of locations (one every ten minutes to preserve battery life) so that we could see its immediate eastward movement from Eau Claire.  For insulation, some fiberglass and activated (shaken) hothandz hand warmers were used inside the Styrofoam rig once the GPS and camera had been strapped in place.  The top of the box was then taped on with more than enough duct and packing tape.
fig 2: the (rough) general idea for the parachute: let the balloon pop and the parachute should open up as air is forced into the opening under the canvass on the trip down


The Styrofoam camera rig was attached with carbineers to the parachute that would hopefully land the apparatus safely upon the balloon’s popping.  The parachute was then attached to the balloon itself at the center of the canopy, so that it would be held taught as the balloon rose but once the balloon was gone it could catch on the trip back to earth (fig).  The balloon itself was a helium weather balloon which was filled large enough that, as one classmate put it, one could easily roll up and fit a person inside (roughly 8 feet in diameter).  It could have been filled further, but as the balloon rises and the pressure outside of it expands, the gas inside the balloon will not be pushed in as forcefully from the outside atmosphere and the balloon itself will expand.  Obviously, it is undesirable for the balloon to expand beyond failure too quickly, so space was left inside the balloon that the Helium gas could expand while maintaining the buoyancy required to lift the apparatus and parachute through the stratosphere.



fig 3: in the dangerous job of transporting Hydrogen, much care is needed. Good thing we're using Helium.

fig 4: Thank you, professor, for recovering the data!


 The final crucial step in completing a High Altitude Balloon Launch is the recovery of the apparatus itself, accomplished in our case by Professor Hupy and a small cadre of students able to drive to the far side of Clark County where the balloon landed in the canopy of the Wisconsin Woods.  The balloon had to land before the GPS unit was sending its signal to the iPad, and Hupy had to saw some branches in order to get at the balloon, but the rig was successfully recovered and with it, the data (fig 4).

Results:


the Curvature of the Earth

The ultimate result was a sweet video of the earth!  The parachute was successful, and out apparatus was found safely dangling thirty feet up a tree in Clark county, just under 80 miles from the launch site.  If you did not know, this is an exciting accomplishment in and of itself.  Several images were collected from the video (given below) and nearing the top of the ascent, the camera apparatus began swaying enough to clearly show the curvature of the atmosphere.  The earth is ROUND, people!!!  More could be done in further projects by attaching some IR cameras to the rig, I personally would like to be able to collect some imagery that would fall under the Landsat 7 band 6 range of data (heat) or perhaps do a night launch and see the lights from the night sky.  Another addition that should have been considered would be an altimeter that recorded the altitude of the apparatus over time, this way we could have an easy tool to determine the height of each image.
the mighty Chippewa River from high above.