Kite aerial photography can give conservation a view from above

Salt pond M5 at sunset at the South Bay Salt Ponds in Northern California. Credit, C. Benton.For the last 15 years, Charles C. Benton, a professor of architecture at UC Berkeley, has been flying kites outfitted with cameras to look at landscapes from above. More recently, Benton has been using kite aerial photography (KAP) in his Hidden Ecologies project to explore what the method can reveal about landscapes. As part of this project, he has been documenting changes at the South Bay Salt Ponds in Northern California where efforts have been launched to restore 15,000 acres of industrial salt ponds back to tidal wetlands and other habitat.

We interviewed Charles Benton about kite aerial photography and the potential for its use in conservation work. We have included some of his images along with a video produced by Make Magazine profiling his work. You can see more of his spectacular images here.

CM: Can you describe a little bit about the methodology involved in kite aerial photography (KAP)?

CB:  The idea is to lift a camera from somewhere around head height to altitudes of up to 400 ft above the ground. I keep my kites below 500 ft in deference to light aircraft.  To lift the camera I use single line kites that are selected for stability.  When I go out in the field I carry about six kites.  After watching the wind for a bit I try to select a kite that matches the wind. It should pull strong enough to lift the camera but not too much more or you end up having to work too hard.  You then launch the kite and fly it up to steady air.  In urban settings that might put the kite at 200 to 300 feet above the ground, out in open terrain you can find steady wind at 100 feet or so.

After the kite reaches steady air you fly it for about 10 minutes to satisfy yourself that the wind is reliable and the kite is performing well.  And then, a few hundred feet below the kite, you attach a little string and pulley suspension called a Picavet suspension (invented by Frenchman Pierre Picavet in 1912). This device has a cross with pulleys in each corner. Lines run through the Picavet’s pulleys to clip onto the kite line in two places.  Below the Picavet cross you attach the camera, which is held in a small robotic cradle - basically a double U-bracket with radio and servomotors.  Under radio control the cradle can point the camera in any compass direction, tilt it from straight down to the horizon, and with the flip of a switch change from portrait to landscape format.  The radio also fires the camera when you want to take the photograph. 

Multiple views of Benton's current KAP cradle. Credit, C. Benton.Once the equipment is rigged to the kite line you just let out more line, the kite flies higher and pulls the camera cradle up after it. If the kite was at 200 feet above the ground when you attached the cradle and you let it rise to 300 feet then the camera that started at ground level is raised to 100 feet above the ground. Once the camera is aloft you can walk around to position the camera in absolute space.  In the South Bay I have hiked five miles along the levees with the camera aloft taking photographs as I go.  I frame each photograph by watching the camera and using the radio to pan and tilt.  After the shot is composed, I wait for camera to be still and then press the button to make the exposure.  It only takes a few seconds per image and it’s great fun.

CM:  You've been doing it since 1995 so that’s 15 years, what is it about the experience on a personal enjoyment level that has kept you engaged for that long?

CB:  Well that’s a really interesting question.  I’m notorious in my family for picking up pursuits, going through the learning curve, and then discarding them rudely to bounce to the next new thing.  I’ve stuck with the kite photography because it’s a challenging blend of many different activities. There’s definitely an aspect of invention to it. In building apparatus from scratch - camera cradles, electronics, and various control devices - I spend many an enjoyable hour tinkering at the workbench. And then there’s the whole aspect of kites and becoming proficient with flying them.  I now sew a variety of kites on an old 1938 Singer Featherweight sewing machine, so there’s the joy of creating elegant and sturdy flying contraptions.  The tactile pleasure of tuning and flying kites is quite satisfying.

Once the gear is in order kite aerial photography is a great excuse to get outdoors.  Over the last ten years I have been out on average once a week to hike and photograph.  These have been wonderful explorations of the Bay area and beyond.  There’s also a social dimension to KAP.  If you have a dog or baby more people seem to come up and chat with you; if you flying a kite with a camera on it everybody seems to want to talk about what you are doing and that’s often entertaining. 

And then there’s this notion of composing images without being at the camera.  I have started calling it "interrogating the landscape."  One of the most frequent questions I’m asked is "can I see what the camera sees?"  And I can, by transmitting video down to an electronic viewfinder. Being gadget prone I had fun making systems to show real time video but I found that I never used them.  In large part this is because what I really enjoy is watching the camera, imagining being there, thinking about the field of view the camera enjoys from 100 feet or 200 feet above the Earth.  As I compose the image in absentia, it involves forming a visual hypothesis.  Later, when I get the photograph back, I get to compare my mind’s eye view with what the camera captured. In doing so I learn an enormous amount.  Why are the relationships between these trees different than what I imagined?  Good heavens, look at the old marsh channels that are evident in the bottom of this salt pond.  And here are a myriad of little animal trails evident in what I thought of as a uniform surface.

CM: How do you think kite-aerial photography could help conservation practitioners with either restoration or land stewardship work?

CB:  You can extract a surprising amount of useful information from an aerial view.  In kite aerial photography you have a relatively low-cost, low-tech platform for remote sensing that operates at altitudes much lower than aircraft flying at 5,000 feet or 1,000 feet.  With this capacity you could document site conditions before and after interventions such as attempts to control non-native vegetation.  You could document a transitional landscape at regular intervals, say yearly, to gauge change over time as might occur after a creek restoration or the breaching of salt pond levees. Since you are in the field with the aerial camera, you can have a broader “ground truth” view for verifying higher altitude remote sensing products.

Lower Codornices Creek near Berkeley, CA in October 2004. Credit, C. Benton.

Lower Codornices Creek in March, 2008. Credit, C. Benton.Yesterday I was out at Drawbridge in the South Bay Salt Ponds (where I have a Special Use Permit allowing access) taking a series of views of Salt Pond A21, which is one of the early ponds to be restored to tidal flow (2006). I’ve been trying to go back about three times year to see how the pond’s plateau, it’s shallow center plain, has been changing now that it’s exposed to the tides.  I plan to do that for maybe 10 years.  It’s fascinating to watch the changes underway. What was once a lifeless plain of deposited gypsum is now sprouting vegetation along the raised edges of former marsh channels.  Two weeks ago I photographed vernal pools at the Warm Springs Wetlands Reserve.  There you see concentric rings of Contra Costa goldfields, downingia, and woolly marbles defining the shape of the pools as they dry out.  In this trip the aerial photographs became a mapping exercise. 

It is evident on our KAP Discussion WWW site that folks from a variety of disciplines – archaeology, wetland restoration, geomorphology, and so forth – are working on extracting rectified maps or three-dimensional point clouds out of the images.  So there are number of more quantitative things you can do.  But the photographs are, at the same time, really nice visual representations of these environments. They present the subject in ways that are accessible to the public, to policymakers, and other folks who don’t think much about remote sensing.  So KAP is useful in public relations and education. 

In March 2006, the levee separating Salt Pond A21 from Coyote Creek was breached connecting the former evaporation pond to the ebb and flow of Bay tidal waters. Images here show April 2006 and September 2009. Credit, C. Benton.Beyond that it’s just sort of open to the imagination.  I’m a Building Science professor in UC Berkeley’s Department of Architecture and I’ve been wonderfully amused by the KAP-related inquiries that come my way.  People are interested in the technique and in ways that it might serve the academy or the professions.  For instance, landscape architects wanting paths crisscrossing a campus or a geographer mapping the breathing holes of manatees in water hyacinth mats in Costa Rica.  I have talked with NASA about automated kites for the surface of Mars and its fast and thin winds.  It’s all a hoot.

CM: What advantages do you think there are to using kite aerial photography versus other methods for obtaining aerial images of landscapes?

CB:  Well, I think KAP is a nice complement to other methods that provide the high, Google Earth-esque views, which give us a broader context.

There are two interesting aspects to kite photographs. The first is that they are intimate. With KAP you can photograph from 10 feet or 50 feet or 400 feet.  In that range from head height to the 500-foot altitude that the FAA sets as a kite’s maximum you can choose your scale by letting out or retrieving kite line. I think the other aspect is it is relatively low cost.  For $200-$300 you can equip yourself with the necessary gear. Brooks Leffler of Pacific Grove, CA produces a line KAP cradle components that makes assembling a working cradle quite easy. It does take a bit of time to become proficient with what are pretty straightforward kites.  And then you have a technique that you can apply over again and again.  With digital cameras you can acquire many, many images at a very modest cost.

CM:  Let’s talk a little about the Hidden Ecologies Project, in which you’ve been engaging the South Bay salt pond landscape.  Can you tell me what your goals are for the Hidden Ecologies project and where the idea for the project originated?

Salt Pond A21 in April 2007 and September 2009. Credit, C. Benton.CB:  Well, the idea sprang out of a sabbatical I spent in 2003 as an Artist-in-Residence at the Exploratorium in San Francisco.  I worked on a number of different projects during that pleasant year.  One of these involved hiking with Wayne Lanier, PhD, a microbiologist with a passion for field microscopes and citizen science. Wayne was working on a text called Hiking with a Field Microscope and the notion of photomicroscopy in the field.  We selected a number of spots around the Bay and went out to photograph the environment through our somewhat unusual vantage points - Wayne through a microscope and me with a kite. 

It was entertaining to see how Wayne’s and my views of the same place were simultaneously divergent and complementary.  I would look at a place through my kite’s eye to see colors and textures that related to physical features like moisture, slope, and salinity as well as other patterns.  Wayne was seeing the microorganisms that adapted to immediate local environments.  In both cases our different views revealed physical gradients and their consequences. We quickly realized it was fun to juxtapose our readings of a given place.  So much so that we are still hiking together today

One of the landscapes we hiked in 2003 was South San Francisco Bay and its salt ponds.  This transitional landscape has changed greatly since the 1850s.  The South Bay has been shaped on one hand by transportation as boats and landings yielded to rail lines which in turn succumbed to highways. Simultaneously, the industry of salt extraction by evaporation changed the bay wetlands in profound ways. Salt production  began with small-scale operations of the 1800s, which were largely associated with boat landings, and now all salt production is controlled by one company, the Cargill Corporation. 

As I started to photograph the South Bay landscape I realized there were layers in the images, very much like layers of architectural tracing paper.  In the layers one sees tracings of cultural geography and the presence of wildlife.  Flood control projects and infrastructure crisscrossing the landscape appear as other layers. It became an interesting project to try to decipher and document the landscape.  While doing so I became much more aware of the South Bay Salt Pond Restoration Project and ended up getting Special Use permits from US Fish & Wildlife and California Fish & Game that permit me to photograph in normally closed portions of the South Bay. This I have enjoyed greatly. 

So Hidden Ecologies is a relatively informal project in which we are trying to document changes in the landscape during this restoration era as they occur year to year.  For instance, going back to Drawbridge and Salt Pond A21, I am working on aerial photographs that document vegetation taking root in the plateau of that salt pond.  While at the same time one of my favorite South Bay subjects for aerial photography are traces of old salt works that date back to the 19th-Century, for in our day these traces are becoming quite dim. It’s just fun to capture these fading geometries as a reading of the place and its history.

CM:  What useful information relevant to the Salt Ponds Restoration Project have you been able to discover from the Hidden Ecologies Project and kite aerial photography in particular that might not have been otherwise easily observed by the restoration practitioners?

CB: Well, that’s a story still in progress.  The agencies have been pleased with my documentation of vegetation coming back to the breached ponds.  But my personal favorite example of novel observation is related to a pump house adjacent to the Don Edwards Refuge headquarters. This pump house, situated on the western flank of the southernmost section of the Coyote Hills, is an interestingly detailed little building sporting a curved roof in the Picturesque style.  I asked over a few years to where did the pump house pump?  No one seemed to know. The pump house was up against the side of the Coyote Hills in a landscape that has changed greatly as highway routes were cut through to the Dumbarton Bridges. 

As I did a bit of research I learned that the early 20th-Century Arden Salt Works No. 1 had its crystallizer beds on the eastern side of the Coyote Hills, opposite the pump house in what is now the La Riviere Marsh. If you look at photographs of it from the 1950s it was a major salt work with piles of salt 60 feet high and large industrial buildings.  And in the current La Riviere marsh you can see the levees and old wooden flow control gates as remnants of the earlier salt work.

In my aerial photographs of La Riviere Marsh I could see a straight line going through this marsh terrain that led me to discover a 24-inch diameter redwood pipe that was buried underneath the marsh.  That pipe went from the pump house through a tunnel in the Coyote Hills to a crescent-shaped distribution basin in Arden Salt Works No. 1. This discovery allowed me to put together the pieces of the puzzle and realize "oh that’s what the pump house served."  It wasn’t a huge tunnel, but I would have never guessed it was there without the evidence of the photographs. I later gave a graphic diagram to the Don Edwards Refuge that shows the buried redwood pipeline and its relationship connecting the pump house to the crescent distribution basin.  In retrospect, I am amused by the fact that on a dozen occasions I had walked past a marsh channel where the redwood pipe was visible without ever seeing it.

Make Magazine features Charles C. Benton.