Aerial photography is a valuable tool for surveying the local topography. Small format aerial photography (SFAP) is a common form of remote sensing, which means to sense something remotely. SFAP runs can photograph a species or phenomenon without disturbing the subject matter. It is noninvasive and therefore benign to the countryside. For these reasons, SFAP is often utilized for monitoring wetlands which are often sensitive to allogeneic influences.
The California San Jose region is undergoing significant wetland reclamation efforts. A more than 2,600-acre wetlands project near Redwood City California will be completed by the end of the year. Environmentalists say it will be a crowning symbol of San Francisco Bay restoration efforts. Destruction of a nearby levee in Alviso will restore 300 acres of a salt pond to their native habitat. Landfills have been used as repositories of sediment. Dump trucks are pouring hundreds of loads of dirt being moved to inner Bair Island daily to raise the ground level before outer levees are breached and the island is returned to tidal marsh. Inner Bair Island is part of the Don Edwards San Francisco Bay National Wildlife Refuge and is an important site for restoration. Researchers estimate that the project will produce pristine wetland conditions not seen since the late 1800s (Race 1999).
After the logistics of travel, accessibility and legal rights were worked out; we could begin our KAP run which involved several procedural steps. First, we had to select the appropriate kite. Kites vary in size, weight, appearance, shape and design. Wind conditions and location can help determine which kite to use for KAP. We needed to find a suitably windy area with steady winds to lift and sustain the kite. For this reason, the Foster City shore near the San Mateo Bridge was selected as an ideal location.
Foster City rests on an engineered landfill and the area was once part of San Francisco Bay’s marshes. Today, the area is reasonably affluent with low crime rates and respectable property value. Foster City is an excellent destination for outdoor recreation and has the most parks per capita in California. Our KAP location was adjacent to one of Foster’s many netted tennis courts and batting ranges. Kite flying is prolific in Foster as a result of the favorable ocean winds. Foster is also the home of world class wind surfing contests. Examples of such wind surfing events can be seen in our photographs.
Kite selection is one of the first steps in the KAP process. For our excursion we chose rigid kites which have a structure to support and maintain their shape. Rigid kites do not have a tendency to collapse when the wind diminishes. We initially choose to use the rokkaku, which is a traditional Japanese kite with a low weight to surface area ratio. The rokkaku has been flown for centuries and it has significant lifting power. Eventually we settled on using a delta kite. These kites have a basic triangular shape and are generally easy to fly (Aber et al, 2010). A ‘tail’ was attached to add weight and stability to the kite we selected to use. Tails also increase weight and drag. This can make the kite fly lower. This was needed in our case because of the strong winds. The kite was assembled and held up in the air to achieve basic lift from the breeze.
We fed rope attached to a handle to the kite in order to control the kite’s height and determine how high it will fly. The rope was wound to a wooden hoop with a reel attached to it. This served to firmly anchor the rope. A kite is attached to the rope which is held by an operator on the ground. A kite can only ascend if more rope is provided by the operator. Below the kite itself, a camera rig was attached to the rope which was then lifted by the kite. This detachable mount was placed on at the starting phase of the kite’s ascent. Detachable mounts decrease the crash risk of the camera. I remotely controlled our rig and therefore was able to aim and direct the camera. I aimed the camera with the help of a yellow rod attached to the front of the camera. This enabled me to know which direction the camera was facing. The rig could move the camera to the right or left and angle the camera up or down which affected the angle of the shots. The rig was U-shaped with a cradle to hold the camera and a frame that moved it. Small servos accomplished the movements (Aber et al, 2010).
Low-cost, light-weight, automatic digital cameras are ideal for KAP. We used a standard 35 mm digital camera for our photos. Since we had two operators, one person handled the rope and the other operated the camera controls. When we finished taking photos, the camera was retrieved from the rig and the kite was reeled in. It is far easier to feed the kite additional rope than it is to reel it in. This is especially true for the heavier rokkaku kite. In our case, one person worked the reel while the other assisted by manually pulling the rope towards the reel. Leather gloves were worn to protect our hands.
Kap is useful for low-altitude observations and is a cost effective alternative to conventional airplane or helicopter aerial photography. The Increasing popularity of high-performance sport and technical kite flying has popularized KAP.
Balloon aerial photography is similar to KAP. A camera can be directly mounted on the balloon or the camera can be mounted in a mast held by the balloon. This is another early form of remote sensing which can be traced back to France in 1858 (Aber et al, 2010). Also like KAP, once in the air the photo must be triggered either remotely by a user or by a timer.
Aber, J. S., Marzolff, I, Ries, J.B. (2010). Small Format Aerial Photography: Principles, Techniques and Geoscience applications. Elsevier.
Race, M.S. (1999). Critique of present wetlands mitigation policies in the United States based on an analysis of past restoration projects in San Francisco Bay. Environmental Management, 9(1), 71-81.