Thursday, March 5, 2009

I Bought an Anemometer

Not the most original title for a journal entry, but it's the truth. I did buy an anemometer: a Kestrel 2000. I can't say it was an impulse buy since I've been looking at anemometers a little over two years now. But the decision to get it right now? I suppose it was.

I've been holding off on getting an anemometer, probably for relatively silly reasons. I can gauge wind pretty well, and the wind models I use are generally accurate. But I've had a bad run of KAP outings recently when I would either find the wind too weak to lift a rig, or too strong to safely fly a kite. I've come home frustrated, more often than not, with little to show for it. An anemometer can't make the wind blow, but it can send a very clear message if the conditions just aren't right.

Another reason I decided to buy one now is that World Wide KAP Week 2009 is coming up soon, and given my finances, there's no way I'd be able to get the kite I've been lusting after (a Dan Leigh Trooper RS, a high-wind delta that can handle the conditions at Upolu Point and Southpoint.) So I took what finances I had and put them into the anemometer. It will be a useful addition to my KAP bag, and if it gives me better awareness of the flying conditions at a new site, it could make the difference between a successful outing and one that ends in damaged or destroyed gear. A sound investment.

But in a larger sense, it was just plain time. A few years ago, if asked which hobby was actually paying for itself the best, I would have to say machining and writing. I wrote a couple of articles for a machining magazine, and when they were published it was the first time I'd ever actually had a hobby start paying for itself. The funny thing is, I used the money from the articles to pay for KAP gear rather than tools. To be fair, I did use some of it to buy two years worth of subscriptions to my machining magazines, so it did go back into the hobby to some extent. But it also helped bootstrap the next.

Today a more truthful answer is that it's KAP that's bringing in the most real revenue. I've sold a number of prints, and have had requests for even larger prints though so far none of those requests have led to a sale. Nonetheless, my KAP hobby has done more to pay for itself than any other hobby I've got. By and large, about half my KAP gear was paid for by print sales. This is better than my ratio for my machine shop and those magazine articles, but it's still not a hundred percent.

I'm at a bit of a leaping-off point. Selling prints is great, but I don't really think that's where I'm going to stop in terms of letting KAP pay for itself. I'm looking at other options, most of which involve doing paying gigs. But for paying gigs to work out, there has to be some guarantee that the flight can happen, and that the right tools are used for the conditions. And for new kite purchases to make sense, I have to be able to demonstrate to myself that I've been asked to fly in conditions that would warrant them.

Hence the anemometer. WWKW 2009 is an excellent opportunity to characterize each of the kites I use, to find out the wind range for each one where I can reliably lift my KAP rig, and the line angle I'm likely to get. This information can be used to plan shots in ways I've never been able to do, and to provide a better guarantee that I can pull off a particular shot.

My goal, by the end of WWKW 2009, is to have a portfolio of images to show to prospective clients, and the ability to know if my gear can pull off a shot that a customer asks for. The anemometer is the first step in this direction.

There's an old adage that as soon as you start to do a hobby for money, it turns into a job. The point, of course, is to keep hobbies as hobbies and to keep work as work. But I'd be lying if I said I wasn't thrilled when I saw my first article printed in that magazine. It only made me want to write more. And when my first KAP print sold, I was ecstatic. I hope this next leg of the venture works out as well.

-- Tom

Thursday, February 26, 2009

KAP Aerial Archaeology and Photosynth

I've been frustrated in my attempts to turn KAP aerial archaeology shots into maps, or even into stitched panoramas that bear any real resemblance to reality. For the most part this is because I really don't have the right tools to get the job done. Photogrammetry, and georectification are not simple to do, and most consumer-level tools aren't suited to the job. Typically this involves software like Photomodeler, Leica Photogrammetry Suite, and GIS software. It also typically requires a grid of GPS-referenced ground control points. I'm not positioned to do any of these things.

But I did run across something that produced oddly pleasing results. It's a Microsoft R&D product called Photosynth. It's not so much stitching software (though I use Microsoft's Image Composite Editor for most of my stitching these days). Instead, Photosynth assumes the shots are not taken from the same vantage point, and finds all the points at which the shots overlap. This in turn is used to create a point cloud of intersection points between shots, so a viewer can place themselves at any of the vantage points from which the photos were taken, and see the scene from that point.

All of which is hard to say, but a lot easier to see. I tried this out using one of the flights from last weekend:



It worked remarkably well. Even more fun is to view it with the images turned off so you only see the point cloud of the intersection points between all the shots. Photosynth does a really good job of picking up the three-dimensional structure of the scene.

I tried it with some of my other KAP flights, just on a whim. The archaeology flights were almost all orthogonal to the ground, but most of the time when I'm out doing KAP I'm busy taking oblique shots rather than orthos. I was amazed at how well Photosynth dealt with this:




I think there's a lot of potential for what Photosynth is doing. There are all sorts of other features I'd ask for (and have asked for) beyond the existing Photosynth interface. Among others, it's ideally suited for picking out proper stereo pairs from a whole collection of images. It would be wonderful to have them all gathered, arranged, cropped, and ready to go.

Even better would be 3D model extraction from a random collection of photos of a scene. One KAP flighti n particular resulted in a really good point cloud for a large truck: a deuce-and-a-half. I'd love to be able to export that truck as a 3D model.

I don't know how much time I'll devote to this, but right now it's pretty fun. And for now walking around an archaeological site using my aerial still shots is as close as I can come to what i want: real 3D scene reconstruction.

-- Tom

Monday, February 23, 2009

More Archaeological KAP

I got to do some more archaeological KAP last weekend. The archaeologist I worked with on Ahu A`Umi was on island a few weeks ago, and tried to fly his camera over the lava flows south of the resorts at Anaeho`omalu Bay. It used to be an active quarry for scoria, which in turn was made into abrader tools for working wood, bone, shell, etc. He wanted to see if the quarry and abrader workshops were visible from the air. Foul weather made for a disastrous KAP trip, so I offered to give it a try the next weekend. We traded some email planning out a strategy (wind direction, time of day, angle of light, etc.) and Saturday morning my son and I headed out.

The wind was certainly better than what he'd faced the previous weekend, but it was still turbulent, tossy, and a little too strong. With some reluctance I put up a Flowform 16 and 15' of fuzzy tail, and got down to business. The nature of lava makes it difficult to walk a consistent grid pattern, and I was reluctant to plant my big feet in anything of archaeological value that might be fragile. Nonetheless I spent about an hour and a half pacing around and chanting my mantra: "C'mon baby, steady wind steady wind. C'mon, don't no NOnono... ok, better, c'mon baby..." (I wonder if I'm the only KAPer who talks to his kites.)

At the end of that first session I took my son to a coffee shop at the nearby resort. He had milk and an apple turnover while I sipped coffee and reviewed my shots. As it turns out I'd used the wrong camera settings, and this combined with the turbulent wind resulted in over half the shots being too blurry to use. But there were enough sharp pictures to convince me to give it another try the next day.

The strangest part of the whole experience was that the entire time I was reviewing the pictures I'd taken, the sound system in the coffee shop was playing, Tex Ritter's "I Got Spurs That Jingle Jangle Jingle". I kid you not.

The next day the wind was much more laminar and of more reasonable speed. My son wasn't interested in going this time, so I took my daughter, who brought a book. This isn't unusual for her. What was unusual was that she only brought one. Normally a quick trip somewhere involves at least a small stack of books. "I never know what I want to read when I get there!" pretty much sums up her reason for this. I've quit asking.

The second day went much better than the first. I launched at a second site the archaeologist had marked out, and moved from there back to the original site I'd flown over the previous day. I found a better spot to fly from, and got a better grid the second go 'round. Toward the end of the session the wind was dying down, so I walked the rig back to my launch spot, where my daughter was still reading. I think she looked up maybe once the whole time. So much for getting out to fly kites with your kids. At least she guessed right on her book. It was what she wanted to read.

My daughter had heard of the coffee shop outing with my son the previous day, and was eager to get the same treat. So back we went, my daughter toting her book and me toting a camera with what I hoped were some better pictures than the day before. This time we both wound up getting chocolate croissants, which we munched while she read and I reviewed my pictures. What I saw put a smile on my face. Not only did the steady wind and the correct camera settings work out, the pictures very clearly showed quarry sites, abrader workshops, and even some petroglyphs I hadn't seen from the ground. Euphoria!

But as I continued to flip through the pictures it slowly dawned on me that the coffee shop was still playing, "I Got Spurs That Jingle Jangle Jingle". They didn't miss a beat.

Those two days generated about 3.5GB of data, probably 2GB of which is actually any good. I sent the disks off this morning in the hope they'll be there some time tomorrow. Meanwhile I've got "My Spurs Go Jingle Jangle Jingle" so firmly embedded in my head that even two hours of Linkin Park couldn't clear it out. I've given up. I fear that the very mention of scoria abrader quarries will forever summon up the jaunty notes of "I Got Spurs That Jingle Jangle Jingle":

I got spurs that jingle, jangle, jingle
As I go ridin' merrily along
And they sing, 'Away, too glad, you're single'
And that song ain't so very far from wrong

Oh Tex...

-- Tom

Sunday, January 4, 2009

Root Cause Analysis

In a previous career, I worked as a systems administrator for twelve years. When working with computer problems, one of the first things you need to learn to do is to see past the symptoms, and treat the underlying condition. It's something called "root cause analysis", and it's the backbone of computer troubleshooting.

In my present career, I do instrumentation at an international astronomical observatory. When diagnosing and maintaining scientific instrumentation, one of the first things you need to learn to do is see past the symptoms and treat the underlying condition. Root cause analysis again.

Recently, my KAP rig has suffered from an oddball problem: Each time I try to rotate the pan axis, there's a lag, and then it starts moving. The first time this happened in the field, I swapped batteries and went back into the air. When the symptoms didn't go away, I assumed both sets of batteries were low.

In a later flight I realized the small pinion in my pan axis gear reduction was loose. DOH! Without thinking about it, I tightened the screw that holds the pinion in place, and put it back in the air. Problem solved, right?

As it turns out, wrong.

About the third time I tightened that screw, I realized something else was wrong. I hadn't done proper root cause analysis; I'd just treated the symptoms of a loose screw. A little more poking around revealed the culprit: The pan axis itself was binding. This put additional torque on the pinion gear, which put extra force on the screw, which pulled it loose, which made the pan axis have backlash, which made for the lag when I tried to rotate it.

ARGH!

The cause of the tight pan axis was a bushing that was too tight in its hole. I made a new one with 0.005" clearance, and everything ran like a well-oiled clock. I also used thread lock compound on the pinion gear screw, so it shouldn't get loose as easily. For good measure I also used a synthetic grease on the two bushings on the pan axis, so hopefully this will be the last time I deal with this problem.

Which is the real benefit of root cause analysis: never having to see a problem come back.

Time to go fly a kite!

Tom

Tuesday, December 30, 2008

Let's Set The Record Straight

I realize this post will probably offend, but it needs writing nonetheless.

Recently, in an online photography forum, I ran across a thread asking if Photoshopped images should be considered in a different class from non-Photoshopped images. To be fair, the person who originated the thread was asking if obviously manipulated images should be posted to a photography gallery. But as the thread evolved people began to ask and answer the broader question. It was some of those answers that were more than a little upsetting.

In any discussion such as this one, or when discussing film vs. digital (which came up in this thread), someone invariably invokes the name of Ansel Adams as the pinnacle of "traditional photography", and as a figurehead for nobility behind the camera. This thread was no different, and indeed his spirit was summoned. Repeatedly. And, if I might say, incorrectly.

Ansel Adams was a huge innovator in his own right, and championed many ideas that at the time were pooh-poohed as vulgar, shocking, useless, or otherwise unacceptable. A good case in point: When Adams started out, view cameras and box cameras were the only show in town. Adams gravited toward the view camera because of the motions it offered, but to the best of my knowledge he never shut out any form of camera or format for the negative. When Agfa began producing cameras to hold their 35mm movie film so people could use it to take still shots, Adams picked one up early on. Various people gave him a hard time about it, but he persisted and took some remarkable photographs using that "pedestrian" gear.

This was far from an isolated incident. It was a pattern throughout his career. He was one of the field testers for Polaroid's products, and was a personal friend of Edwin Land. He also tested Kodak's first color film products, though he admitted the strength of his work lay in black and white. And he was a big proponent of image manipulation.

I'll say that again just so people are clear: He was a big proponent of image manipulation. This is made abundantly clear in his numerous writings. In his book, "Examples - The Making of 40 Photographs" he goes so far as to show his initial contact print from his negatives, his test prints, and his final print along with the dodge and burn notes for several of his photographs. Contrast adjustment? Yes. Dodging and burning? Yes. Tonal range compression and expansion? YES. (And you thought HDR was new... nope.) If it could be done in the darkroom, it was fair game.

So what about digital vs. film? Unfortunately Adams didn't live long enough to see digital hit mainstream, but in the introduction to "The Camera" (I think... my copy went wandering when I loaned it out a few years ago) he clearly stated that he was excited by the prospect of digital cameras and digital photography. I don't think he ever referred to it as digital imagery as so many film proponents do. Digital photography.

So please, stop invoking the name of Adams unless you really want his opinion. He made it pretty clear over and over and over.

"I have been immensely pleased with many creative explorations I have seen; they are evidence of great imagination and the awareness of enduring qualities of art. I often observe that the more "far-out" any work appears at first, the more exciting and valid it may prove to be."

-- Ansel Adams - "Examples: The Making of 40 Photographs"

I began to write a response to the thread in the forum, but in the end I erased my reply and moved on. Enough passionate photographers for one day. One more wasn't going to change anyone's opinion or do any more to provide an answer to the original question. As a friend of mine put it, "Opinions are like assholes. Everyone's got one." I'm no different.

- Tom

Wednesday, December 17, 2008

Anti Bokeh

Bokeh (derived from Japanese, a noun boke ぼけ, meaning "blurred or fuzzy") is a photographic term referring to the appearance of out-of-focus areas in an image produced by a camera lens using a shallow depth of field.[1] Different lens bokeh produces different aesthetic qualities in out-of-focus backgrounds, which are often used to reduce distractions and emphasize the primary subject.

Wikipedia
Almost everyone who has put a camera in manual mode, or who has used a manual-only camera, has played with depth of field. A shallow depth of field produces the bokeh effect described above. A wide depth of field brings more of the frame into acceptable focus.

But there are limits to what you can do with an aperture ring. Close down too much, and diffraction at the aperture starts to work against you, blurring out the picture. So what do you do with a shot that has a lot of range to cover?

One solution is to use a large format camera with motions and take advantage of the Scheimpflug Principle. I won't go into the details here, but the upshot is that you can tilt your plane of best focus by tilting the lens or film holder. If, say, you're photographing a field of flowers stretching from your feet out to infinity, it would be impossible to bring the entire field into sharp focus using the aperture ring alone. But you could tilt your lens and shift your plane of best focus until it coincided with the field of flowers. The entire field would be in focus, but everything above it or below it would begin to go out of focus. This is partially the reason why photographers like Adams and Weston were able to get incredibly sharp sweeping landscape shots, and it's the reason why many landscape photographers continue to use large format cameras to this day. (Including me!)

But what if you need everything above and below that field of flowers to be in focus as well? You can still stop down, and broaden your depth of field somewhat above and below. But again, there are limits. Eventually diffraction begins to work against you, and you start to fuzz out the overall image. Where can you go from here?

Back in 2000, I ran across GRAFICA Obscura, a web site written by Paul Haeberli of SGI. It described a method of taking a stack of images shot at different focus distances, and selecting only the sharpest bits of each image in order to combine them into a single, sharpest image. Paul used an edge-finding filter to build his layer masks, a technique that worked, but not perfectly well. I made some attempts to use his technique, but I ran into a number of problems and no real successes.

Skip forward to 2008 when I swapped out my Nikon Coolpix 5600 camera for a Canon A650 IS. One of the reasons I chose the A650 was that it could run CHDK, a scripting language that can run on top of the Canon firmware in many of their compact cameras. I was interested in running CHDK for several reasons, one of which was a bracketing script that was far more flexible than the bracketing available in the Canon firmware. Among other things, it let you bracket your focus.

All of this would've put me in no better position than I was already in with Paul Haeberli's technique, but times change. At some point in those intervening years, Alan Hadley wrote a package called CombineZM that automates and improves on the technique Paul Haeberli described. The combination of CHDK's bracketing script and CombineZM's ability to stack the images yields a tool to get infinite depth of field out of a scene.

Anti-Bokeh

Optics Bench

It's not for every photographer, and certainly not for every situation. But it's one more tool to add to the tool belt. And now that that tool is there, it's something to think on when heading out into the field.

Tom

Monday, December 1, 2008

The Photo Competition

Last year I found out that one of the local galleries hosts an annual black and white photography competition. This year I decided to enter. It's been one of those "learning experiences" we're told to appreciate. Phrased a different way: it's been painful.

Rules for photo competitions always look straightforward until you actually try to submit something. This one has an up-front screening process to weed out what makes it into the gallery. "Unmounted prints or slides". They're actually pretty explicit on this part of the requirements, and even bother to mention that submitted materials will not be returned. Three 8.5x11 prints and $45 in submission fees later, and I'm in.

Why three? I wanted to include at least one aerial, at least one traditional landscape, and at least one macro. Besides, I figured they'd can at least two of my shots, leaving only one to be printed large, matted, framed, etc.

Lesson #1 - If you submit it, you may have to print it.

Yep, all three pictures made it through the screening. So how to prepare the gallery prints? 18x24 is the maximum size called out in the rules. But are these maximum linear dimensions, or is it a square inch kind of thing? I punted on this question this year by submitting images that cropped well to that ratio, but some of my more printable pictures have 2:1 or even 3:1 aspect ratios. If it's a linear dimension limit, a 3:1 print would come out at 8x24. Historically, for this photo competition, every square inch counts and the larger the prints typically the more favorable the judging. Printing 8x24 would put any 3:1 panoramas behind the larger, more traditional aspect ratio prints. In the end I wound up printing 17x24 for one, and 18x24 for the other two. I'll wait 'till next year to submit panoramas. Printing for the three photos came out to $60.

Lesson #2 - Framing takes time.

Our submissions were due early in October, and we were supposed to have word whether our shots made it in by November 1st. Only none of us heard until closer to November 16th. Framed prints were due on December 1st, so that only left two weeks to print, mat, and frame the shots. I called the local frame shop, and they said there was a two week lead time on framing. Since I didn't have prints in-hand, that meant I had to find another way to get the framing done. In the end I wound up using an online framing supplier and bought Nielsen metal frames and mats cut to size. The supplier wouldn't ship glass through the mail, so I got acrylic.

When the package arrived I got busy. It wasn't until I'd started on my second print that I realized they'd cut all three mats to 17x24. With one week to go and no time to get replacement mats, I called the local frame shop to see if I could get them to at least make mats on a same-day basis. Lucky for me they were happy to do so. But because so many other people were getting prints framed for this competition, they were running low on certain supplies, like acid free mat boards. I got 6 ply mats instead of 4 ply, but they look nice.

Lesson #3 - Humidity is a bear

By the time I got the other two prints framed another fact of life in Hawai`i was staring me in the face: humidity. When I worked at the frame shop in Pennsylvania, any time we were doing archival framing we hung the prints in the mat using what's called a "linen hinge". Two pieces of acid free linen tape held the print at the upper two corners, and the print was allowed to drape across the mat aperture. This worked great, and when done properly would last for a hundred years or more. I did the same thing with my prints. Only with the huge humidity changes we get here, the print had expanded and buckled against the mat.

Times have changed, and now there are archival methods of dry mounting prints to acid free backer board. Next time I'll dry mount the prints and avoid the humidity issue.

Lesson #4 - Acrylic is fun for science projects

I had reservations about using acrylic. We did occasionally use it on super-huge prints when I worked at the frame shop, but for everything else we used glass. Getting glass clean can be entertainment itself, but conscientious application of Windex with a lint-free wipe usually got the job done. Still, we kept pieces of black velvet around to use as lint collectors once the glass was clean. On a bad day, it could take ten minutes or more to get a piece of glass ready. I heard there's a frame shop in Boston that bought up the cleanroom equipment from a chip manufacturer that closed its doors. That is a brilliant idea. If I ever go into the framing business myself, I'll follow their lead. The additional cost in HEPA filters is worth it.

Acrylic is a whole 'nuther ball game. It collects static charge the way kittens collect "Awwwww!"s. As soon as it's clean, something wants to stick to it. The very act of wiping dust off charges it even more. No matter what you do, the stuff is dirty. It's a pain. I did finally get the acrylic mostly clean, but it's not what I'd call a spotless job. Next year? Glass.

Lesson #5 - You have to show up

The framed prints are due in the gallery Monday the 1st. I've known this for over a month. They've been sitting in my office at work, ready to go. I could've handed them in Friday last week, but didn't. I wanted one more chance to see them before saying goodbye.

I've been scheduled to work at our remote facility, starting Monday the 1st. I've known this for a week. But somehow the two ideas didn't connect. Not until 2:30am Monday morning, anyway. I went from sleepy to bolt-upright awake in less than a minute, and even broke out in a sweat along the way. I still hadn't made caption cards, I still hadn't printed out the pricing cards. And they were in my office, not at home and certainly not in the gallery. I wouldn't get back into town until the gallery had closed. DOH!

I spent the next two hours printing cards, re-hanging the other two prints that were now suffering from humidity shifts, loading them into my wife's trunk, and trying to come up with a way to ask her to take my prints to the gallery. Now I'm going to go to work at our remote facility on about four hours of sleep. Next year? I'll plan to be in town when the pictures are due.

Lesson #6 - I know I'd do it again

Despite all the pain and anguish, I'd do it again in a heartbeat. I just hope all three prints sell. After everything I went through, I don't want a single one coming home with me.

-- Tom