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Return to Kiholo Bay

Posted by Tom Benedict on 08/09/2009

I’ve flown a camera at Kiholo Bay a number of times now, but for some reason I’ve never been all that overwhelmed by the sweeping landscape pictures I’ve come back with.  They’re either too long and narrow, or don’t really capture the sense of the place, or are just plain awkward.  In a way this may explain why I keep going back.  But when I do go back, I tend to photograph it the same way.  Photography is one of those things where living in a rut just doesn’t work out in the end.

Rather than repeat what I’d done before (ok, rather than repeat my mistakes) I decided to take a fresh look at the problem:

Kiholo Bay is a gorgeous stretch of water just south of Anaehoomalu Bay.  It’s got a fantastic reef, a really good view of Hualalai, and the inlet is one of the most striking features on that entire stretch of coast.  It’s one of the few spots along the Kona coast of the Big Island that has a scenic lookout.  So what was missing?  I realized I’d been focusing on the inlet at the expense of everything else!  Once I decided what I wanted to include in the frame, it was a matter of figuring out how to do it.

I decided I wanted the inlet as a diagonal slash across the bottom of the frame, with the reef getting plenty of space.  I wanted a horizon line that included Hualalai, the volcano above Kailua-Kona, a really clean sky, and the whole stretch of shoreline along Kiholo Bay.  With that in mind I pulled up Google Earth and started fishing.  In the end I also wound up going back to some of my earlier photography there, but in the form of a Photosynth.  This combination of tools and ideas gave me what I wanted: a vantage point.

There’s a spot about five hundred feet north of the inlet, about four hundred feet inland, and roughly three hundred and fifty feet above the ground that would give me the angle I wanted.  You could do it from a helicopter with FAA clearance to fly at that altitude over what is admittedly not a populous area, but it’s a lot easier to do this sort of thing from a kite.

The mornings have been sparklingly clear, but by mid afternoon the volcanic gases coming out of Kilauea creep north of Kailua-Kona and cover the Kona coast in a thick haze.  It can make going to the beach less than pleasant.  But it makes photography downright impossible.  The ideal time of day for the picture I wanted was about an hour before sunset.  But waiting for the light meant losing the atmosphere, so I opted to go early in the day.

Monday was a holiday, so I checked the local weather conditions.  By 10am the wind around Kiholo Bay was supposed to be four knots onshore with little to no turbulence.  Perfect for slack-line flying, and ideal for a picture of this kind.  I grabbed my gear and headed out.  It’s a half hour drive to Kiholo Bay, and another half hour hike across the lava.  By the time I reached the water I realized something was terribly wrong.  My four knot steady onshore wind was more like a two to ten knot gusty down-shore mess.  It was with some trepidation that I pulled out my rokkaku and got my camera airborne.

It wasn’t the steadiest flight in the world, and at one point my rig came down and landed hard on the lava.  Some recent modifications to my rig made for a safer landing, but my heart was still in my throat when I saw it sink behind a ridge and felt the line go slack.  But seconds later it was airborne again, and I was able to reel it back in and check it out.  Everything worked perfectly.  I didn’t even bend the leg brackets on my rig.  It’s a testament to the good design work and engineering Brooks Leffler puts into his KAP rig products.

I knew the field of view I needed for the picture, and knew my camera didn’t have a wide enough field to pull it off.  So I planned to use stitching software right from the start.  This was important to know, because the methodology is different when going for individual frames and composites.  This time I wanted a composite.  Rather than use the tried and true Gigapan style pattern that most KAP panoramas are made with, I used a modified version of one pioneered by Vertigo, one of the French KAPers: burst KAP.

In traditional KAP panorama work, the rig is pointed in one direction, stopped, and a picture is taken.  The rig is then tilted down slightly and a second picture is taken.  This process is repeated until the camera is pointed vertically.  At that point the rig pans to a new “slice” location and the process starts over.  With a good camera and rig, this takes roughly five seconds per shot.  For a ten shot composite, it’s almost a minute of photography.  A KAP rig can move a lot in a minute.

In burst KAP panorama work, the rig is set to spin on its pan axis, and frames are fired off as fast as the camera can take them.  A combination of high shutter speeds and carefully calculated pan speeds makes for very fast, but still quite sharp work.  In this case I needed more height than my camera could give me, so I did the burst in two passes.  To be more accurate I did it in four passes, starting with the camera horizontal and ending with it near vertical, making a single pass with the pan axis for each tilt angle.  In post-processing I only used the first two tilts, however.

Rather than waste a trip, I photographed Kiholo Bay this way over and over as the kite and camera moved around the sky because of the shifting wind.  The end result is that I made numerous burst KAP sets with the camera at a variety of altitudes.  When I got home it was a matter of choosing the set that gave me the angle I wanted.  Nine images, taken over roughly fifteen seconds, supplied the imagery necessary to build the composite I had imagined.

Kiholo Bay

The final image came out at 9057×4800 pixels with no stitch errors during compositing.  This is sufficient to print it 60×32″ with no visible pixelation.

I truly enjoy the serendipitous moments that happen when doing photography in general, and KAP in particular.  There’s a particular smile I’m sure every photographer wears when they go through their pictures at the end of the day and find something they really weren’t expecting.  But there is a great deal of satisfaction to be had from thinking through a photograph, planning the composition, and then pulling it off despite not having things go quite as expected.

– Tom

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KAP at Hawaii Volcanoes National Park

Posted by Tom Benedict on 24/06/2009

For a long time, it has been a dream of mine to do KAP at Hawaii Volcanoes National Park on the Big Island of Hawaii.  I’ve wanted to do this ever since I first suspended a camera from a kite line.  But when I first asked about the possibility of doing KAP in the park, the answer was a very definite no.  I’ve been trying to teach my kids to get permission first, and not have to ask for forgiveness later, so even though it hurt at the time, I followed my own advice and remained patient.  Apparently that approach worked, because I’ve now been invited to do KAP in the park.  Not only that, but the rangers who invited me would like me to fly over the active vent in Halemaumau Crater.

Gulp!

It’s one thing to have a dream, especially one that’s been filed in the pipe dream category for so long I never thought it would happen.  It’s quite another to have an invitation, and to need to set dates and times. In the hopes of getting some feedback from someone who had done similar work, I posted all this to the KAP Forums.  The responses I got were very helpful.  Aside from the obvious safety issues, there were a couple I hadn’t thought about:

  • Because of the distance from the surface of the lava lake, heat damage isn’t likely.  Even with the kite line at zero degrees off the horizon, it’s several hundred feet down to the lava lake.  Not a problem.
  • Chemical attack is an issue, but probably not a big one.  Nylon and polyester, the two materials present in my kite sails and my kite line, are prone to attack from sulfuric and hydrochloric acid, but only at concentrated levels.  One of the folks on the KAP Forums said that the UV damage from sunlight exposure would probably outweigh the chemical damage from exposure to acid gases.  Besides, the acid gases are concentrated in the plume.  Keep the kite and line out of the plume, and all’s good.
  • The aluminum parts of the rig are anodized, and shouldn’t be prone to chemical attack.  The anodizing process uses sulfuric acid to grow the oxide layer on the aluminum, so further exposure shouldn’t cause issues.  Anodized aluminum is far more prone to chemical attack from caustics.
  • The camera electronics may be damaged from even mild acidity, so I’m planning to bag the camera.  Optical coatings may also be prone to attack, so I plan to use a sacrificial UV filter over the lens.  If it looks like the coatings are being damaged, I’ll have to re-consider my approach.  But the camera should remain unharmed.

There were other safety issues raised about the actual kite flying.  This is one area that will take some direct experimentation since there’s no way to predict what any of these will mean:

  • The Halemaumau crater is down inside the Kilauea crater.  The crater walls of the Kilauea crater are about 330′ high upwind of Halemaumau, and are about 10,000′ away from the launch site.  This presents about a 30:1 distance:height obstruction up-wind.  This is at the edge of what is acceptable for placement of meteorological equipment.  There shouldn’t be a significant wind shadow at that point, but there may be turbulence that will have to be taken into account.
  • There are two ways that heat can be transported from the lava lake into the atmosphere.  The first is convective.  The second is radiative.  Both will be present.  Convective heating should be confined to the gas plume coming out of the vent.  So long as the kite isn’t in the plume, it should be ok.  Radiative heating may cause issues even with the kite well above the plume.  One KAPer who spent time flying a KAP rig over a volcano in Vanuatu said he experienced massive thermals that fell off as the kite slid sideways away from the vent.  In the end his kite inverted and flew into the ground, despite all his efforts to get it back under control.  This must be tested before a rig is hung from the line.

And finally there are the personal safety issues to be dealt with:

  • Find out what personal protective equipment should be used (hard hat, steel toed boots, respirator, etc.)  Most of these I use regularly at work, so it will be a matter of finding out which PPEs are necessary, and under what conditions they’ll be needed.  If it’s necessary to use a respirator, I’ll need to shave.
  • Do not clip my winder onto my person at any time.  This has come up on a number of flights I’ve done that involved flying out over cliffs.  So long as there’s a cliff, don’t clip on.  Period.  With a winder in-hand, it’s always possible to let go.  With the winder clipped on, a sudden gust and an over-sized kite could drag the kite flyer off the cliff.
  • Find out how long I get before we have to head back.  This last one will determine what approaches I take, and whether I can get all the testing done up front before the photography begins.

All in all, it looks like I’ll need at least one dry-run test without a load, and then with an 860g water bottle dummy weight to match the weight of my rig.  If there are strong thermal effects, or if I can’t successfully keep the kite, line, and rig above the plume, I’ll have to pull the plug on the flight.

On a better note, the pictures themselves should be quite good.  I was concerned that the lava lake would be vanishingly small in the picture frame: a spot of orange.  But at a 40 degree angle between kite flyer and camera, the spot should be just under a thousand pixels wide.  At a 10 degree angle, it should be just under two thousand pixels wide.  Aiming will be critical, but the results should be worth it.  The lava lake should dominate the frame.

Which brings up the last point:  How to actually photograph the place?  I’m planning a couple of approaches:

  • Open with ortho autoKAP using an intervalometer set to a five second interval.  I get roughly 400-600 images per chip.  This gives me between half an hour and 45 minutes to fly a camera over the crater and get orthogonal pictures.  During this flight all my attention will be on the kite and camera, without having to worry about a remote.
  • Next do a second autoKAP flight, this time using the prototype controller a friend and I have under development.  This is where we’ve been putting the bulk of our efforts for how we like to capture a place with a camera, so it’s the best approach I could take for this part of the photography.  With the frame rates we’ve been getting, this is about a 30 minute flight before the chip fills up.
  • Finally, if time allows I’d like to do remote controlled KAP.  I would only do this if time allowed, and if the flying conditions were such that I felt comfortable splitting my attention between the remote and the kite winder.  If in doubt, this part of the program would be cut.  But this is the one I’m most looking forward to.

But in a larger sense, what I’d like to do is demonstrate KAP for the folks at the park, and show that it can provide access to vantage points that aren’t otherwise available, that it can be done safely without significant risk to personal safety or to the safety of the park itself, and that it offers the park a very real, very available method for close distance remote sensing.  In a perfect world, my follow-up to this would be to build out a set of rigs for the park rangers, and to help them get started in the world of KAP.  I think it has a lot to offer.

And I can’t wait to see how the pictures turn out!

Tom

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Photosynth from a Kite

Posted by Tom Benedict on 12/06/2009

Photosynth is a web-based program that lets you assemble a number of pictures of a single subject and combine them into a 3D navigable scene built from your pictures.  It doesn’t create a 3D model, but it does arrange all the still pictures so that a viewer can move around the scene and see each picture from the angle it was taken at.  People have made some truly phenomenal synths of a range of subjects.  It’s well worth a visit.

Of course I had to try it from a kite.  I pulled out the raw pictures from a couple of previous KAP outings and came up with some decent synths:

As it turns out KAP is very well-suited to making synths.  To make a well-connected synth requires a number of pictures, capturing the subject from multiple angles.  By its very nature KAP takes pictures from a variety of angles and positions.  I’ve made a number of KAP flights specifically to generate a synth, but for the most part they have been the serendipitous outcome of a flight otherwise geared toward still photography.  These are some of the better ones, taken with Photosynth in mind:

But there are times when things just plain don’t work.  Photosynth doesn’t like water because picture-to-picture, water varies, so there’s nothing really to tie one image to the next.  I’ve had some oddball results from synths that included large bodies of water.  Special techniques need to be used.

One in particular, a synth from a set of flights over the Kiholo Bay Inlet, had a number of problems with it.  Discussion with the Photosynth development team led to the conclusion that it was the water, the lack of a good pool of overlapping images, and just a poor sampling of the area in general that led to the problems.  I’m planning a second trip to Kiholo Bay to try to take a better set of pictures for making a synth there.

An added side-benefit of Photosynth is that in the process of tying all the images together, it creates a point cloud indicating which points in the images tie to points in other images.  A good set of high detail pictures can generate a very dense point cloud.  It’s possible to extract the point cloud and use it to create a rendered 3D image of the scene.

Photosynth Surface Extraction

This model was generated using the point cloud from the Waikoloa Archaeological Site in the list above.  Considering there was no GIS data, no ground control grid, no real spatial or metric information of any kind, it’s remarkably accurate.  Though it also shows some of the problems with this method.  The road surface in the cut is quite smooth, so there are patches without any points in the point cloud.  These show up as gaps in the surface.  There are also some very rough areas of terrain on the same size scale as the mesh spacing in the surface.  This caused issues as well.  All in all, though, it’s a neat technique.

But the flight at the Kiholo Bay Inlet has been the most instructive of all.  Because of the sparse data set, it really pushed the Photosynth algorithm, and indicated some new approaches that would help with making synths from a kite.  When I go back, the plan is to:

  • Get the camera airborne over the water, and walk the length of the pond while pointing it at the far shore.  Take pictures every five seconds to get good overlap between frames.
  • Turn the camera 180 degrees and walk back the other way, taking pictures of the near shore.  Again, take pictures every five seconds to get good overlap between frames.
  • Turn the camera 90 degrees to face down the length of the pond, and tilt it down until the horizon is just out of view.  Walk the length of the pond taking pictures every five seconds.
  • Turn the camera 180 degrees to face back the other way down the length of the pond, and walk back taking pictures every five seconds.

At this point there should be enough images with enough overlap to make very good references for both shores, and enough images to tie the two shores together into a single frame of reference.  From here on out images can be taken to place them inside this frame of reference:

  • Get the camera to a good high altitude over the far shore, 50-100m or so, and begin taking hemispherical panorama sets.  Start at one end of the pond and work toward the far end, moving maybe 10-20m between sets.  This should provide a view in every direction from any point above the pond, and the high altitude should let the straight-down ortho shots tie into the frame of reference we generated above.
  • Make a second pass at a lower altitude with the camera over the near shore.  Similar spacing between hemispherical sets.
  • Finally, switch back to manual control and take detail sets of some of the features at the site (resting turtles, the turtle observation station, various rock features, key features along the shoreline, etc.)

At the end of the day, the pictures need to be culled to remove:

  • Blurries – Photosynth doesn’t work well with them, and they’re no fun to look at.
  • Bad exposures – For the same reasons as above.
  • Frames with more than 50% water in them – This was one of the key issues with my first attempt at this site.  Photosynth doesn’t deal well with water.

Finally, put all the images into Photosynth and see what comes out!

It’s a long process, and the number of images involved can be quite large.  Each set of images for the hemispehrical panoramas is 40 to 48 frames.  Ten spots along the pond can generate almost 500 images.  The two passes will crank that number up to about a thousand.  Throw in the initial framework images, and the total will probably exceed 1500 images.  This is more than I did at Green Sand Beach, by far my largest synth to date, but it should make for a very complete synth of the Kiholo Bay Inlet.

I should have a chance to try this over the weekend, if the weather holds.  Time will tell.

Tom

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Kiholo Bay Inlet

Posted by Tom Benedict on 07/06/2009

Worldwide KAP Week is over for 2009, but KAP is a year-round activity for me.  The past six months we’ve been plagued with volcanic gasses coming out of the Halemaumau Crater on Kilauea, but a few days ago the tradewinds came back, blew the volcanic plume out to sea, and for the weekend, at least, our sweeping panoramic views were back.  It was a tough call whether to do ground-based photography or to fly a camera, but in the end the kites won.

Unfortunately because we’d had such uncharacteristic wind for such an uncharacteristically long time, the wind models I rely on to decide where to fly were reporting bogus information.  The models predicted 6-8 knot kona winds at my house, whereas I could look outside and clearly see it was blowing 10-12 knot tradewinds.  When technology fails, the eyeball prevails.  I packed my gear and my son and drove down to the coast.

In addition to editing the book for Worldwide KAP Week 2009 and starting work for a book of my own, I’ve also started making some KAP posters.  But in order to print them at the size I would like, I’ve been faced with the resolution limit of my photography.  I’ve been getting my posters printed using the El-Co Color Labs Internet Special.  They use a Durst Theta printer, and print on Fuji papers using Fuji chemistry.  A quick word about digital printing:  There are two basic ways to make a digital print.  One is to use a transfered medium, like a dye sublimation process, or an inkjet process.  The other is to take a photographic paper and to expose it to light.  Each has its own advantages, but I like the second for the bulk of the photo work I do.  The Durst Theta printers expose photographic paper to light, and then develop the paper the same way a film-based photo lab would.  The result truly is a photographic print.

But resolution is the key.  The Durst Theta can print at up to 254 dpi.  At 24×30″ that’s an image 6096×7620 pixels, or a 44 megapixel image.  I’ve made prints at resolutions as low as 150 dpi on a Durst Theta printer, but I prefer not to go below 200 dpi.  For this set of posters 200 dpi is my lowest resolution.  This is still a huge image, and the bulk of the pictures I have on file simply aren’t up to the task.

This has driven me to re-visit sites where I’ve been able to make good photos, but without the resolution necessary to print.  So I was overjoyed when driving down the coast to find that the wind at Kiholo Bay was a nice 7.4 knot on-shore.  Perfect.

Kiholo Bay has a fantastic reef, and is an outstanding place to do snorkeling and SCUBA.  There’s a good dirt road that will take you all the way to the water’s edge, so there’s no great hardship to get there.  It’s a popular spot, but not so overcrowded as, say, Hapuna Beach.  But if you’re willing to go a little further and work a little harder, Kiholo Bay has a feature that’s not to be found anywhere else in the Islands: the inlet at Kiholo Bay.

Wainanali`i Pond

There are two approaches to the inlet.  One is around the water’s edge from the park at Kiholo Bay.  The other is to park off the side of the highway, a little more than half a mile away.  The walk across the lava is not bad, but it’s not a traditional trail.  The “trail” is a series of paint splotches on the rocks to tell you vaguely where to go.  But the ground is rough lava.  It’s more than possible to get hurt, and this time I did.  I twisted my ankle.

A Study in Salinity

What makes the inlet special is that it’s a relatively deep patch of water with a very shallow mouth connecting it to the sea.  The level of the pond rises and falls with the tides, but tidal flow causes very little mixing of the water inside the pond.  As a result it is highly stratified, with seawater salinity levels at the surface, and high salinity levels further down.  The salinity at the bottom of the pond can easily be double that at the surface.  Select euryhaline organisms inhabit the higher salinity levels, turning the water its characteristic opaque aquamarine blue, whereas the surface water is all crystal clear.

The shallow mouth and opaque water in the inlet make it the perfect habitat for honu, or Pacific green sea turtles.  The pond is relatively free of predators, so the honu are able to forage in some measure of peace and security.

Flying Solo

The honu swim in the high salinity waters at the bottom of the pond, moving like phantoms through mist.  Every once in a while one will come to the surface for air, slipping into the clear waters above and then descending once more into the obscuring depths.

The arm of land that cuts the inlet off from the sea is mostly composed of rounded rocks rather than the hard lava flow that makes up the opposite shore.  This provides a good spot for honu to come up out of the water to rest and sun themselves.  Honu are protected by law, so people are not supposed to approach or touch them. A 20′ minimum distance is required, but I try to maintain at least 40′ between me and a honu on land.  With the low traffic of humans at the inlet, and the lack of predators, this provides a wonderful spot to study them.

A Study in Turtles

Hawaii Preparatory Academy (HPA) maintains a remote observation station at the Kiholo Bay Inlet.  The station has had some upgrades since my last visit, and now sports three PV panels, a fixed mount infrared camera, a fixed mount visible camera, a pan tilt zoom camera, and an RF link back to Waimea.  To learn more about this installation and the research program, you can visit:  HPA/NOAA Sea Turtle Research and Conservation Program.

But for me, the Kiholo Bay Inlet is simply a beautiful place that I have the privilege of being able to see and photograph.  It’s not the easiest place to get to, and there’s no fresh water or shade to speak of.  But Kiholo Bay isn’t here for us, it’s here for the honu.  I just feel fortunate I get to visit from time to time.

Idyllic

Tom

(Note:  I have been calling the Kiholo Bay Inlet by the wrong name: Wainanalii Pond.  This is how it is commonly labeled on maps, hence my mistake.  But during a conversation with Bobby Camara, he pointed out that the village of Wainanalii is a two hour canoe ride to the north of Kiholo Bay, and that it was destroyed by the same lava flow that created the inlet.)

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Why Take Pictures From A Kite?

Posted by Tom Benedict on 28/05/2009

“Why take pictures from a kite?”

It’s a question I hear fairly often when I try to describe kite aerial photography to someone who’s never seen me at work.  Oddly enough I never get this question when I’m out in the field.  The reason for this, I’m pretty sure, is that once you see it being done the answer is fairly obvious.

Lighthouse from Up High

In short, because I can.  And because it works so very very well.

The related questions, “Why not do it from an airplane?” or “… a helicopter?” or “… a UFO?” also have a pretty short answer:  Because I can’t.  Or at least I choose not to.  For starters, I don’t have access to a UFO (though as it turns out I do.)  By the same token, I don’t have access to an airplane or a helicopter, either.  Sure, I could rent one, but I’m not a pilot.  I could rent a pilot, too, but they cost a lot.  In Hawaii where I live, an hour in a Robinson helicopter that’s had its doors removed, but not its pilot, costs roughly $350.  Not too expensive on the face of it, but it comes with some restrictions.  First, it’s only for one hour.  I regularly leave my KAP rig in the air for hours at a stretch, waiting for just the right light or just the right action.  Next, helicopters and airplanes all have to stay over 1000′ above ground level.  A KAP rig stays less than 500′ above ground level.  The views really are different.  And finally, three hours in a Robinson would pay off all of my KAP gear with change left over for making prints.

Top of the Lighthouse II

The second point in the previous paragraph, the one about viewpoint, is often lost on people.  If some altitude is good, wouldn’t more altitude be better?  If your goal is to look for camouflaged rocket batteries or some other secret military facility, sure.  This is why a great deal of the military’s reconnaisance is done from satellites.  But if the goal is to produce an intriguing photograph, more altitude often spoils the view.  If greater subject distance was always preferable, landscape photographers wouldn’t need wide angle lenses, would they?

Top of the Lighthouse I

Besides, the camera equipment necessary to render fine details from even a thousand feet away is not the most affordable, or even the most portable thing in the world.  I would argue that the previous photograph could not have been produced with a long lens and a longer subject distance.  But even if it could, without a stabilized camera platform and a truly remarkable camera and lens, the level of detail avaialble from such a photograph would not be all that impressive.

Too Close for Comfort!

It’s one thing to stand at the base of a lighthouse and wonder what it looks like on top, and only be able to satisfy your curiosity by driving to an airport, renting a helicopter, convincing the pilot to fly to the lighthouse, and only then find out the answer.  It’s quite another to reach into your backpack, pull out a kite, line, and rig, and by golly find out right then, right there.

Why take pictures from a kite?  Because I can.

Green Sand I

— Tom

The photos used in this post were all taken from a camera suspended from a kite line during World Wide KAP Week 2009.

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