Balloon Mapping

Balloon Mapping I

INTRODUCTION

Our Geospatial Field Methods class will be launching two balloons for mapping purposes.  The first balloon launch will be a mapping balloon to map the newly reconstructed campus mall at the University of Wisconsin-Eau Claire.  The second launch will be a high altitude balloon that will capture aerial imagery of the area surrounding the launch point.  In order to have successful launches, we worked together as a class to construct the balloon rigs and to plan the future steps of the launch.

METHODS

Figure 1-Reviewing
Reference Materials

Our class reviewed reference materials provided by our instructor before planning the execution of our balloon launch (Figure 1).  This allowed the class to gain a better idea of what exactly we would be doing and what equipment would be needed.  The instructor had supplied the equipment needed for both balloon rigs as well as a scale.

After we reviewed, the class formed groups to concentrate on specific aspects of the launch:

                -construction of the Mapping rig

                -construction of the High Altitude rig

                -Parachute Testing

                -Payload weights of both rigs

                -Design of implementing continuous shot on the cameras

                -Implementation and testing of the tracking device (Figure 8)

                -Filling the balloons with helium and securing the balloon to the rig

My group concentrated on the payload weights of both rigs.  We had to measure each and every item so when it comes time to construct the rigs, we will know exactly how much the rigs weigh.  We weighed both balloons, the parachute, two carabineers, all three cameras and memory cards, every type of rubber band, small and large zip ties, rope, string, empty liter bottles, hand warmers, Styrofoam, a “minno thermo” container, and a yellow cord with a metric scale.

Figure 2- My group weighing items

We also took pictures of each item and gave that picture a detailed label that matched the payload spreadsheet.  These pictures were uploaded into the class folder so each student has access to the images.  This is important because there is a large number of items and everyone in the class needs to know which weight corresponds to which item.  The total payload for the High Altitude Mapping Rig was determined by the end of the class period and was added to the payload spreadsheet(Figure 9).

Figure 9- Weight Chart

While my group weighed the items, other groups tested and timed the parachute, constructed rigs for both balloon applications, determined the best camera for each launch and designed the implementation of the continuous shot (Figure 3) and tested the tracking device.

Figure 3- Implementing Continuous
Shot

Figure 4- Building the Mapping
Balloon Rig

DISCUSSION

Each group made sure to document their progress and outcomes during this activity.  In the end, the documentation will allow the entire class to build both the Balloon Mapping rig as well as the High Altitude Mapping rig.  The documentation provides a framework of what has been done and what still needs to be done before we can initiate the launches.  At the end of class time, one mapping rig was constructed, "The Hindenburg" (Figure 5).

The process of preparing for the launch of both of the balloon rigs was somewhat chaotic because there were so many aspects that needed to be considered.  By breaking up into groups, students could apply their strengths to their category.  This helped because people who were better at construction worked to build the rigs (Figure 7) or people who were better at organizing the data concentrated on the payload weights, ect.

Figure 5- "The Hindenburg"

Figure 6- Balloon Mapping Rig

Figure 7- Construction of the Rigs

Figure 8- Testing the Tracking Device

The class had to work together to share the equipment because each group needed every item throughout the class period.  We also worked together to communicate to other groups what we had accomplished and what still needed to be done.  At the end of the class period, all of the groups should have recapped what was accomplished so everyone was on the same page.

CONCLUSION

As stated earlier, this is just the first step in our class’ balloon launching.  The data and designs we came up with will be improved upon and then implemented into the balloon launches.  It was a team building activity for each group and for the class as a whole.  This will help in the future steps of this process because a strong team will be needed to overcome the possible obstacles for this project.

The next steps are to design how we will fill the balloons with helium and then connects the balloons to each rig.  Once this is determined we will be able to move onto the fun part-the launch!

Balloon Mapping II

Introduction
Our class has created and implemented a balloon mapping rig in the previous weeks.  This is an innovative and cost-effective way to collect aerial imagery.  In order to use the aerial imagery, the images collected by the balloon must be georeferenced and mosaiced.  This report concentrates on the process of both mosaicing and georeferencing images from our balloon mapping.

Methods
Two techniques were used to mosaic the aerial imagery.  For both techniques the images were uploaded to a desktop after the balloon was grounded.  The techniques used were very different; the first technique was using a website called mapknitter, the second technique was georeferencing through ArcMap.

Mapknitter is a website that provides tools necessary to "knit" together aerial images to create a map.  A Google Imagery base layer was offered by the website.  This base layer could be used as a reference for the placement and scale of the imported images.  The images had to be uploaded to the site one at a time.  Once an image was uploaded it could be scaled and moved so it could be located in the correct position.  This was done repeatedly with numerous images until the images were sufficiently placed.  Once this was complete, the map had to be exported so it was visible to all users of the mapknitter site. The map I created on mapknitter is seen in Figure 1.

Figure 1: Aerial Imagery map created with MapKnitter (mapknitter.org)

The second technique was georeferencing with ArcMap.  Because there was such a plethora of images collected by the balloon, the class divided sections of the campus into groups to lighten the workload for all students.

I started a new map document then loaded data that would be beneficial to the process of georeferencing.  The data included a polygon feature class for my groups section and a CAD polygon feature class of the buildings on campus (Figure 2).  I used an imagery basemap provided by ESRI in the beginning of the process as a reference.

Figure 2- Group Section & Buildings feature classes

After this data was added the process of georeferencing could begin.  This process if not very complicated, but it is time consuming and must be done carefully.  Below are the steps necessary for georeferencing.

1.) Turn on the georeferencing toolbox (Figure 3)

Figure 4: ArcGIS Desktop 10.1 Georeferencing toolbar

2.) Click the "Control Points Tool"

3.) Zoom to the current image

4.) Click a point on the current image that can be easily referenced to the buildings feature class

5.) Zoom to the Group Section layer

4.) Click on the area that matches the point previously selected on the current image

The image will move to a new location using the georeferenced point; do this repeatedly for each image until the image is placed in the correct area.  This process is repeated for each image until an area is accurately represented on the map.

Zooming between layers is helpful because the aerial imagery is not spatially referenced and is located very far from the needed area.

The georeference control points can be edited using the "Control Points Table" (Figure 5).  The control points are labeled by a number and when clicked on, the control point will be highlighted on the map.  Editing mainly consists of deleting control points if it distorts the image or the image's location on the map.

Figure 5: Control Points Table

Discussion

Georeferencing in ArcMap 10.1 resulted in a better outcome than Mapknitter.  The control points 

Conclusion

Figure 6: Final mosaiced raster of the aerial images