Overland Expo: Kite Aerial Photography

Herbie

Rendezvous Conspirator
Since a few people saw my kite photography rig flying at Overland Expo, and several more people have expressed interest since I posted one of the resulting photos, I thought I would post a thread to give as much info as possible about the rig and the theory behind it.

IMG_6843.JPG


First off, credit for inspiring me to undertake this goes to three entities, almost simultaneously: First, DesertBoater mentioned a friend who used a kit towed behind a boat used for overhead photography in a thread on UAV Photography. Second, Randal Munroe of XKCD fame (the best comic on the web, IMHO), as I found his early kite experiments while snooping his site, and MAKE Magazine, as they did a feature on their idea of a simple KAP rig around the same time. In my opinion, the MAKE magazine project was overly complicated and didn't reflect modern reality in terms of cheap and simple possibilities for kite photography, but I'd like to think that mine does.

So, after a little research into "Kite Aerial Photography", or KAP, it turns out the "key" bit of technology needed for good photographs is the "Picavet Cross", or "Picavet Suspension", named for Frenchman Pierre Picavet who in 1912 described a rigging system that keeps the camera (relatively) level to the horizon despite changes in the kite string angle. Here is my simple rig:
IMAG0499.jpg


Just about everything I needed to make this rig I learned from KAPER e-zine, with this excellent introductory page. The excellent animation on that page will demonstrate exactly what the Picavet does for you, if it's not clear.

For my use, I wanted to have the option of taking this rig along when I went hiking or backpacking, so I emphasized lightness and simplicity over everything else. I used some scrap carbon fiber strips I had lying around from my Battlebot days, added a couple screw eyes and some fishing line, and voila'.

After you have the suspension, the next thing is the camera cradle. Many KAPers are really serious and have radio-controlled servo driven gimbal rigs that let them pan/tilt the camera while in flight. Mine is much more simple, just a pair of angle brackets from the hardware store with some carriage bolts and wing nuts, using what's referred to as the "LL Design" here. If it isn't obvious from the photo above, my rig is totally static, so to change the aim point I just walk down the kite line, re-aim, and release again. It turns out I don't have to fly very high to get great photos, so this isn't tedious at all.

The last bit of "tech" for the KAP rig, and possibly the only area I have added anything "new", is the shutter release system. This is where I felt the MAKE Magazine build got WAAAAY too complicated, using a mechanical shutter release based on a wound rubber band dampened with silly putty, if I remember correctly.

Instead, I've basically turned a $40 Canon SD450 P&S I got from Craigslist into a time-lapse shooting camera and just let it fly and shoot, then sort out the pictures later. They key is a Canon camera running the Canon Hack Developers Kit (CHDK). This sounds ominous and complicated but basically you just select the correct image for your model of camera, load it onto the SD card, boot the camera, and off you go. In my case, I'm running a user-written script called "Ultra Intervalometer" which is basically a very customizable soft-intervalometer (camera speak for shooting on intervals). I set the initial delay, set the inter-photo delay, and then when I'm ready to fly I just hit the shutter release button once and let her fly. Incidentally, using CHDK also lets me capture images in RAW format, something which this older P&S doesn't normally do.

Now I've got a rig, but I still need something to fly it from. My best KAP kite so far is this basic 14 sq ft sled kite I got from my local tourist kite shop. It's a self-inflating sled with no rigid structure, and it all folds up into the storage bag that acts as the drogue/tail - about 14" by 6", collapsed. This kite is super easy to launch solo, even in mild wind, and is fairly stable even in high wind. More importantly, it has WAY more than enough line pull to lift my rig (about 12oz, w/ camera, if I remember correctly). I could probably get fancy with an RC rig with this kite, but I like the simplicity. If you ever want to make another Dad look bad in front of his kid, show up with this kite at a park on a breezy day when he's trying to launch one of those cheap Disney-branded diamond kites you get at the drug store. While he runs backwards trying to get enough lift under the kite to get it into the breeze, you unpack the sled, clip it to the kite line, give it one good tug and.... UP! (Remember to wear gloves, this kite has some serious pull)

Here's one more example of the results I got with the rig:
IMG_6840.JPG


As a bonus, due to a happy accident, during my first flight at OvEx11 I accidentally bumped the camera into "video" mode. The intervalometer was still running, so it was shooting a series of short movies as it triggered the release over and over. I stitched these back into a single video so you can sort of get a camera-eye view of me bringing the kite down to make aim adjustments. You can also see the BEST feature of a rig like this - it attracts attention, especially from children, whenever you fly it:

 
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bobDog

Expedition Leader
Hey thanks....you've got me interested now....I'll have to try this later this spring!:coffeedrink:
 

Tucson T4R

Expedition Leader
Very cool Herbie. Thanks for sharing the details. Looks like a lot of fun.

Someone else here was going after setting up a high end remote helicopter with a DSLR camera. I would hate to crash that puppy! :Wow1:
 

Mr. Leary

Glamping Excursionaire
Very cool Herbie. Thanks for sharing the details. Looks like a lot of fun.

Someone else here was going after setting up a high end remote helicopter with a DSLR camera. I would hate to crash that puppy! :Wow1:

Lol. I remember that thread.

Thanks for sharing, Herbie. Do you think anyone would take issue to me borrowing the idea for some of our pics this year?
 

Herbie

Rendezvous Conspirator
Lol. I remember that thread.

Thanks for sharing, Herbie. Do you think anyone would take issue to me borrowing the idea for some of our pics this year?

You mean building your own rig to take pictures of your events? Heck no, as far as I can tell the whole KAP community is all about sharing info to get others into it. I've found even with a "low" flight of 25-50 ft, you get photos from such a completely different perspective that they're almost always interesting. It's great for capturing the "scale" of big group activities, as you can see in my above shots. I can't wait to shoot the next SoCal expo group meet & greet. In short: Do it, but be sure to post the results!

One other thing I forgot to mention in my first post:

Some folks (including that Picavet Basics page I linked) build a little "carrier" so they can store the picavet suspension once it's all rigged up. I can never keep mine from getting tangled, and having it rigged detracts from the ability to collapse it and make it small, so I went a different direction: You can see in the photo that there are some small labels at the corners and a big label on one side: That's basically a cheat-sheet for the rigging order. I keep a small spool of fishing line, the two line-trees (bent coat hangers to attach to the kite line), the center ring, and a carabiner or two (for holding the rigging up on stuff while I get setup) in a ziplock bag and just rig the line on-site. It only takes a couple of minutes.

If I'm flying from multiple locations on the same day, or know I'll be using things again soon, I just clip a carabiner into one end-ring and hang it on the T-end and slip the other end-ring over the point of the massive 14" sand-stake that I usually use to anchor the rig: (I DID mention that my sled has a lot of line pull right? This stake is barely adequate)
careygroundstakelong.jpg



At least that way I can carry things around, it's just not really adequate for long-term storage as things can get tangled unless the cross is always hanging down.
 

Michael Slade

Untitled
Wow, that is a really cool rig. CHDK is the most under-rated thing on the planet. You can make your really pretty crappy Canon p&s camera do magical things. Have you gotten yours to shoot RAW yet?

Nice job and thanks for sharing!
 

Paladin

Banned
Someone else here was going after setting up a high end remote helicopter with a DSLR camera. I would hate to crash that puppy! :Wow1:

You might be talking about me?

I'm working on it, but not the DSLR yet. Just a P&S and a ContourHD.

Some guys have crashed DSLR's and they are surprisingly durable. One guy buried it 6" in the dirt, and it still worked after some minor repairs.
 

Herbie

Rendezvous Conspirator
CHDK is the most under-rated thing on the planet. You can make your really pretty crappy Canon p&s camera do magical things. Have you gotten yours to shoot RAW yet?

I agree, it's enough to keep me coming back to buying Canons in the SD line, anyhow.

Yes, I have RAW versions of all the photos I shot from the kite, it's just a checkbox in the menu!

I know some of the guys doing serious time-lapse stuff also take advantage of being able to manually set aperture, shutter speed, etc. so that they get consistent exposure shot to shot, which makes a big difference in having your time-lapse not "flicker". That's the kind of stuff you just normally can't achieve until you get to pro-sumer level equipment, so it's awesome to have it in just a small/lightweight package.
 

Tucson T4R

Expedition Leader
You might be talking about me?

I'm working on it, but not the DSLR yet. Just a P&S and a ContourHD.

Some guys have crashed DSLR's and they are surprisingly durable. One guy buried it 6" in the dirt, and it still worked after some minor repairs.

Yep that be you. :elkgrin:

I for one am looking forward to your experience once you get airborne and start shooting. Looks like a crazy fun hobby (or potential business) on either the Heli or Kite platforms.

Heck, just flying the RC helicopters without the camera would be a kick. :sombrero:
 

Paladin

Banned
The kite thing is interesting because... flying a helicopter is damn hard! And no matter what, one man can't fly, and control the camera at the same time. I was disappointed to see the swinging going on in the video however.

But the whole thing popped into my mind.... replace that picavet cross with a gyroscopic sled. Here's the concept. Twin, parallel axis, contra-rotating gyroscopes will stabilize the sled, so no more wild swinging. They can also be used to pan the camera easily, and even tilt. It's hard to see what's going on here, but this guy built a Bi-copter using these principles. It does not use a swashplate like a real tandem heli (chinook). It uses only inertial controls, and tilt on the axes. He set up this test, replaced the blades with disks, to prove that control is derived not from the thrust, but the gyroscopic forces.

http://www.youtube.com/watch?v=TrHDFdOenXQ&feature=player_embedded#at=20

This could be greatly shrunk, and hung from a kite, allowing remove control tilt and pan, and stabilization with very few moving parts. Just two motors, one servo, a helicopter gyro and a V-tail mixer.

Could be done for $50-100.

The disadvantage with the kite is obviously that you need a strong wind. And can't choose your locations as freely. But man... is it simple. Kind of like a pole cam, without the pole.
 

Herbie

Rendezvous Conspirator
You'd be surprised at how little wind you really need. It scales pretty well with the weight of the rig, and like I said in my first post, my 14sqft sled is more than I need to a lightweight rig.

For the math-inclined, here's a nifty calculator that lets you play with kite angles, etc. to see how much lift is really needed: http://www.kaper.us/NotLinked/Kites.html
(Natural kite angle is a factor of kite design and wind, so there are limits for each type of kite)

The swinging you saw was directly a result of too much wind (and gusty wind, at that) and a little bit "too short" of a picavet suspension rigging. Rigging exactly the same, but with a longer length of line, will let the rig hang down further from the kite line and gives a better damping effect. A heavier rig of course does a fair bit of damping too.

But you're absolutely right, the main "plus" for a KAP type rig is that it is DEAD simple to operate. Drive a good heavy stake into the ground to tie the kite line off, and you could basically let it run unattended as long as the wind holds out. In fact, the next time the SoCal ExPo group meets at the beach, I'm hoping to get there early, launch the kite, and set the intervalometer to shoot at much longer intervals, like once every few minutes, and just let the kite hang out all day getting a real "time lapse" of the comings and goings of the event.

The hardest part for me is keeping the picavet happy (untangled) while I launch the kite. At OvEx11, I used the string trees to hang the rig from the flagging tape on the edge of the vendor area while I got the kite up, then walked the kite line down to meet the flags so I could rig the trees one after the other. When I shoot at the park at home, I usually have my daughter and her stroller, so I hang the rig from the handle of the stroller while I launch the kite.
 

Tucson T4R

Expedition Leader
When I shoot at the park at home, I usually have my daughter and her stroller, so I hang the rig from the handle of the stroller while I launch the kite.

Oh sure Herbie, just tangle your rigging up with your daughter's stroller and drag her up for the ride of her life. :Wow1:

Just poking you with the visual that flashed into my warped mind. :sombrero:
 

Herbie

Rendezvous Conspirator
Oh sure Herbie, just tangle your rigging up with your daughter's stroller and drag her up for the ride of her life. :Wow1:

Just poking you with the visual that flashed into my warped mind. :sombrero:

I can hear her now.... "wheeeeeeee!"
(She's a speed demon)
 

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