The View Up Here

Random scribblings about kites, photography, machining, and anything else

More Fun with Panoramas

Posted by Tom Benedict on 27/04/2010

I got out a couple of times over the weekend to shoot more panoramas.  One that I did over Puu Huluhulu on Saddle Road turned out quite well.

Kipuka Puu Huluhulu and Mauna LoaThis was done just after 7am, with a really steady breeze coming in from the Hilo side.  The panorama consists of 21 photos taken in two stripes, something only possible with steady wind and a good solid kite.  It’s something of a milestone for me for a number of reasons:

  • I’ve been trying to photograph Puu Huluhulu under these conditions for over a year, and for over a year I’ve been thwarted.
  • This was the first time I’ve been able to really test Autopano Pro since I picked up the license last week.  I’m overjoyed by how well it worked.
  • This is the last time I ever want to depend on the wind to be just right to let me make a two-stripe panorama.

That last bit probably takes some explanation.

I long ago quit making kite aerial panoramas the traditional way, in favor of a method developed and proven by a French KAPer who goes by the name of Vertigo in the KAP forums.  His method, which he calls “Burst autoKAP” involves spinning the rig at a fixed rate and holding the shutter button down so the camera can take pictures as fast as it can store them.  With a good high shutter speed, this method works flawlessly.  Using the traditional method, a 360 degree panorama took roughly a minute.  That’s a whole minute during which the wind can change, the camera can drift, and things can get out of alignment.  Using Vertigo’s burst method, a 360 degree panorama takes my rig and camera roughly ten seconds.  The resulting panoramas stitch much more easily, with fewer errors and fewer panoramas lost to camera movement.

But your panorama can only be as tall as the vertical axis of your field of view.  Unless, of course, you shoot two stripes of photos at two different camera tilts.  A two-stripe 360 degree panorama takes my camera and rig twice as long as a single stripe, or twenty seconds.  While far better than the traditional approach (which would take upwards of two minutes), it’s still longer than the ten seconds a single stripe panorama can be done in.  Twice as long, in fact.  With twice the chance that the wind will shift, things will move, and the panorama will be spoiled.

Later in the weekend I made an attempt at a panorama of Ali`i Drive in Kailua-Kona.  The light was wrong, and the wind was gusty and light, but it let me test the concept and scout a better location to fly from when the conditions warranted it.  But the wind was too variable to allow me to try a panorama in two stripes.  Had I been relying on that technique for capturing that image under perfect conditions, the day would have been a dead loss.

So let’s go back up to that statement I made about the panorama only being as tall as your camera’s vertical field of view.  Panorama photographers have known this since they started assembling panoramas off of photographic print.  The solution is simple: rotate your camera 90 degrees so your wide axis is vertical, and you get more coverage.  It results in a slightly slower burst pattern in order to maintain the same percentage of overlap between images, but it’s far better than the 2:1 time penalty you take making a two-stripe panorama.  So the next question is how to rotate the camera in the KAP rig.

There are two approaches.  One is to change out the tilt bracket for one that holds the camera vertically.  The other is to add in another axis of motion to the KAP rig that allows the operator to rotate the camera’s orientation on the fly.  I went with this second option.

There is no pre-built kit of parts for doing this.  Most people who build a rig with this horizontal/vertical orientation axis build them on their own.  There are a handful of examples out there, but no one yet makes a kit where you can just click “HoVer Option” and get the appropriate parts.  Even so, the parts that are available from Brooxes can get you very very close.  That’s where I started.

My approach is to use my existing tilt bracket for the camera mount.  I added a utility frame and a Brooxes Better Gear Guide with 1:1 gearing in it for the HoVer axis.  This then replaces the tilt frame in my existing KAP rig, and the whole thing is re-balanced.  That was the idea, anyway.  Unfortunately life rarely works out the way you plan.

For starters, the 1:1 gearing won’t bolt straight in.  There is a clearance issue between the bracket and the side of the servo.  Likewise with everything in the normal orientation, there’s interference between the side of the servo and the utility frame as well.  Milling the required clearance was a quick job on the mill, though an equally good job could be done using a hand nibbler and a file.  I don’t own a nibbler, and the one we keep at work was… well… at work.  It was quicker to mill the parts out.

Next, there is no standard part to go from a Brooxes Better Gear Guide to the chopped-up remainder of a tilt frame.  The BBGG includes a nice aluminum gear hub that gave me the idea for how I wanted to mount the remains of my tilt frame: a 0.875″ diameter piece of aluminum, threaded to take the BBGG shaft with a set screw to lock it in place, and a bolt hole pattern to attach it to the tilt frame.  This can be made quite thin, and should keep the camera from overhanging the end of the BBGG too much.

From this point on it’s a matter of clearance.  I had to un-do a number of modifications I’d made to my KAP rig in the sake of keeping things compact.  The clearance required for the HoVer axis is quite large.  But after careful measurement, I think I can squeeze everything in.

Sorry, no pictures yet.  It’s still a work in progress.  But things are progressing well.  The rig should be finished before this coming weekend, and I hope to get a chance to put it through its paces in the air before Saturday morning.  If things work out well, I hope to get out early again this coming Saturday and catch that morning light on a new subject to go with the panorama I made of Puu Huluhulu.  But this time it’ll be using a single stripe of images and a camera rotated to vertical at the flip of a switch.

Tom

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