Balloon Mapping

Introduction
Our class is embarking on an aerial mapping project of our college campus.  A large helium balloon was used with a camera attached facing downwards.  A long string was then tied to the balloon so we could move the balloon around campus, as well as set the desired altitude of the balloon.     

Methodology
The imagery was gethered using a large balloon that was launched into the air about 400 feet.  Attached to the balloon was a camera facing downwards.  Once the balloon was at the desired altitude, we walked all around campus to collect as much imagery as possible.  After this process was completed, the images from the camera were located onto the computer.  Relevant images pertaining to the assigned area were selected and were georeferenced.  Georeferencing is accomplished by adding control points to the image and matching them to the corresponding location on another image that is already georeferenced.  The first step in this process is to display an already georeferenced image, followed by turning the georeferencing toolbar on.  An image that needs to be georeferenced is then loaded, and fit to the display. 

Figure 1. Aerial image to be georefenced displayed.

Using the add control points tool, a control point is clicked on the image, and then again on the corresponding location on the already georeferenced image.  These control points can consist of the corners of buildings or sidewalks, trees, or any other distinctive featuers.  This process is repeated until the image appears to be in the correct location.  When georeferencing my images, I tried to have at least 10 points.

Figure 2. Aerial image with control points displayed.

Once done georeferencing an image, it must be rectified to be saved as a new file.  Then, other images are added to the display and georeferenced until the desired area is covered by the newly georeferenced images.

Figure 3. Additional images being added and georeferenced.

When all of the desired images are georeferenced, the mosaic to new raster tool is employed to combine the images into one file.

Conclusion
Figure 4 shows the final mosaic of the images that I georeferenced. 


Figure 4. Final mosaic of imagery.