Forum : Advice & Critiques

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Topic: Synth from Kite Aerial Photography (KAP)

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tbenedict (Over 1 year ago)
K suggested that I start a thread, sort of as a rallying point for other people who are doing kite aerial photography, and to discuss what works, what doesn't, and what ideas might create better synths of a given location.

So if you're doing kite aerial photography, please chime in.  Here are a couple of other people I've found doing KAP synths (in the hopes they read this and provide their input!)

yone-p
http://photosynth.net/userprofilepage.aspx?user=yone-P

andygates
http://photosynth.net/userprofilepage.aspx?user=andygates

BirdEye
http://photosynth.net/userprofilepage.aspx?user=BirdEye

NikkiLee
http://photosynth.net/userprofilepage.aspx?user=NikkiLee

SRIDEL
http://photosynth.net/userprofilepage.aspx?user=SRIDEL

DeltaKap
http://photosynth.net/userprofilepage.aspx?user=DeltaKap

tbenedict
http://photosynth.net/userprofilepage.aspx?user=tbenedict

Lots of kite aerial synths to look at.  Any pointers, please let us know!

Tom
tbenedict (Over 1 year ago)
If anyone's interested in getting into KAP, here are a couple of URLs to get you going:

Discussion Forums:
http://steel.ced.berkeley.edu/kap/discuss/

Gear Supplier (Americas):
http://www.brooxes.com

Gear Supplier (Europe):
http://www.kapshop.com

Flickr KAP Groups:
http://www.flickr.com/groups/kiteaerialphotography/
http://www.flickr.com/groups/kaprigs/
http://www.flickr.com/groups/kapkites/
http://www.flickr.com/groups/kapbits/
http://www.flickr.com/groups/kapgeneral/

I'm trying to keep track of what gear I use on each flight so I can include it in the descriptions of my synths.  I hope this is useful for anyone who's interested in getting into KAP.

Tom
dariusmonsef (Over 1 year ago)
Wow, nice work rounding everyone up.  Now I'm off to explore KAP synths...
tbenedict (Over 1 year ago)
Photosynth came up recently on the KAP forum, so there may be more KAPers here soon.  (I hope so, anyway!)  In time I expect the list will grow.

Tom
tbenedict (Over 1 year ago)
Ok, here's a consideration for doing aerial synths from a kite:

There are two broad-stroke categories for how KAP rigs work.  One is to use a radio of some sort to control the camera and rig (RC KAP).  The other is to have a controller on the rig so it controls itself and tells itself when to take pictures (AutoKAP).  Cameras running an intervalometer fall into the latter category.

When using an RC KAP rig, there's a tendency to only take pictures when you have a subject framed up.  Which is great for doing still photography, but not necessarily for creating synths.  When making synths, I'm learning there's a lot of utility in taking transition pictures while panning between subjects, or when moving from one location to another.

KAP flights where I walk the rig over to a subject, photograph that subject, then walk to another subject, etc. don't synth well.  They wind up with low synth percentages and multiple synths you have to switch between.

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tbenedict (Over 1 year ago)
KAP flights where I never stop taking pictures, even when moving from one subject to another, tend to synth better and have more unified views.

With an RC KAP rig, this is a conscious decision that needs to be made while the flight is in progress.  With an AutoKAP rig, this more or less happens on its own since one of the main characteristics of an AutoKAP rig is that it never stops taking pictures.  If the goal of the KAP flight is to create a synth, I think the better route is to use an AutoKAP rig in the first place.

Which is a good thing, since AutoKAP rigs are a lot more straightforward to build than an RC KAP rig.  They're cheaper, too, since there's no requirement to have a ground-side transmitter.

If anyone is interested in building an AutoKAP rig for making aerial synths, there are a couple of different types of rigs inside the broad category of AutoKAP worth considering:

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tbenedict (Over 1 year ago)
The first is simply to have a camera running an intervalometer that's suspended from a kite line.  A number of cameras come with intervalometers on them, and the bulk of the Canon compact cameras can run CHDK or SDM, both of which offer intervalometer scripts as part of their standard offering.  The only trick there is to come up with a way to mount the camera so it can be suspended from the kite line.  This is one example:

http://www.flickr.com/photos/tbenedict/2873597732/

It only looks down, and was developed specifically for doing ortho shots of archaeological sites.  But the same idea could be used with the camera tilted up at an oblique angle.

There is no provision for repositioning the camera mid-air.  It's simply a way to hold the camera so that it can take pictures on its own.  Just to demonstrate that this idea has some merit, it's how this synth was made:

http://photosynth.net/view.aspx?cid=f363450f-3e05-479b-aebf-64d31c4be0b6

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tbenedict (Over 1 year ago)
The second method is to use a camera that has a fairly wide field of view, and to tilt it at a fixed angle while rotating it around the pan axis with a servo.  This is the idea behind the BEAK rig:

http://www.flickr.com/photos/kyteman/469251924/

It looks down at a fixed angle, but rotates, taking pictures periodically so there is overlap for stitching panoramas.  Or, in the case of Photosynth, so there is overlap for connecting the photos into a synth.

This approach is slightly more expensive than the first type, but not by much.  Parts for a BEAK kit run about $80US, minus the kite, line, and camera.  In terms of camera gear, it about on par with a good lightweight tripod.  (To be fair the tripod I'm lusting after at the moment runs about $650, so my definition of "good" and "lightweight" may differ from that of others.)

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tbenedict (Over 1 year ago)
The third method is to use a fully articulated rig that has both pan and tilt axes, and to use a controller that can drive both.  One of the more common controllers for this is the AuRiCo, and is carried by most KAP gear suppliers.  It's basically a limited version of a Gigapan controller, but designed for hands-free airborne operation.  Depending on how its switches are set, it will move through one of several patterns of pan and tilt, taking pictures all the while.  This setup is popular at events like kite festivals because the rig can take pictures all day long, often resulting in a number of good 360x180 degree hemispherical panoramas.  Read that another way, and it makes for lots of overlap for creating synths.  This is a typical AuRiCo rig:

http://www.flickr.com/photos/wind-watcher/2217186163/

This is only slightly more expensive than the BEAK, only really needing one additional servo to complete the picture.

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tbenedict (Over 1 year ago)
And if you do have an RC KAP rig, the addition of an automatic controller is an inexpensive way to expand your KAP gear to make creating aerial synths that much easier.

Tom
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