Western Carolina University, Cullowhee, North Carolina

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Balloon Mapping @ WCU

By Rachel Phipps

Mission

A group of students attending Western Carolina University, under the guidance of Adam Griffith, took on the project of mapping the campus using aerial photography in the fall of 2010. The project was initiated because there was concern about the Google Earth images that covered the campus and the surrounding Cullowhee area. Satellites for Google Earth images only pass by every couple weeks and our campus is experiencing lots of change through construction of new buildings and new facilities that Google Earth does not reflect. Also, the images are of extremely poor quality, and unless you are familiar with the campus it is difficult to discern cars and some buildings and small structures.. This is where we come in: our images taken only 1000 feet in the air are of much better quality and clarity than those in Google Earth, and when we complete the project we would love for Google to insert our images into their maps.

Notes

The photographs were taken by suspending a camera inside the top of a 2 liter soda bottle and attaching this setup to a 250 gram balloon which was on 1000 feet of string (see materials picture d). We also used the same soda bottle-camera rigging attached to a kite to test which produced better photos (balloon). The balloon was pulled by hand by students on the ground and was navigated around campus, making sure to steer clear of tall buildings, trees, and other high objects that could snag the string. The camera was 14 megapixels and was set on continuous mode so it would take about a picture per second while up in the air. After several flights, we discovered what conditions were most suitable to our endeavor. The best photos were taken when the sun was out with no clouds in the sky. Lights winds were fine, but heavier winds caused the balloon to be jerked around, which would not allow the camera to focus. Advice for other mappers would be that no matter what equipment you use to take your aerial photos, make sure it is sturdy enough to withstand a fall! We experienced a malfunction where the balloon burst while we were pulling it in, and the camera struck pavement roughly. Luckily it survived with little to no damage.

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Cartographer notes

I was very impressed with how well the image acquisition went for the WCU student group. The imagery im mostly comprised from two separate flights on separate days. There was some variation in the shadows within adjacent areas for this reason. As always with vertical mapping. The imagery has been registered at the ground (surface) level. If you look closely at different buildings you will see differences in perspective angles, due to the balloon/camera not being directly overhead of each building. This is just a common characteristic of low altitude remote sensing and is overcome with the cartographer using the ground level to register the scene in vertical mapping harmony. Some post processing was also done on overexposed areas of the imagery that were a little blown out from high albedo such as some of the areas of pavement, and some of the rooftops. -Stewart

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Notes

The photographs were taken by suspending a camera inside the top of a 2 liter soda bottle and attaching this setup to a 250 gram balloon which was on 1000 feet of string (see materials picture d). We also used the same soda bottle-camera rigging attached to a kite to test which produced better photos (balloon). The balloon was pulled by hand by students on the ground and was navigated around campus, making sure to steer clear of tall buildings, trees, and other high objects that could snag the string. The camera was 14 megapixels and was set on continuous mode so it would take about a picture per second while up in the air. After several flights, we discovered what conditions were most suitable to our endeavor. The best photos were taken when the sun was out with no clouds in the sky. Lights winds were fine, but heavier winds caused the balloon to be jerked around, which would not allow the camera to focus. Advice for other mappers would be that no matter what equipment you use to take your aerial photos, make sure it is sturdy enough to withstand a fall! We experienced a malfunction where the balloon burst while we were pulling it in, and the camera struck pavement roughly. Luckily it survived with little to no damage.

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Cartographer notes

I was very impressed with how well the image acquisition went for the WCU student group. The imagery im mostly comprised from two separate flights on separate days. There was some variation in the shadows within adjacent areas for this reason. As always with vertical mapping. The imagery has been registered at the ground (surface) level. If you look closely at different buildings you will see differences in perspective angles, due to the balloon/camera not being directly overhead of each building. This is just a common characteristic of low altitude remote sensing and is overcome with the cartographer using the ground level to register the scene in vertical mapping harmony. Some post processing was also done on overexposed areas of the imagery that were a little blown out from high albedo such as some of the areas of pavement, and some of the rooftops. -Stewart

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