Re: [photo-3d] Hyperstereo from airliner - frame rate?

[Roger Loper <roger@xxxxxxxxxxxxxxxx>]

William Gartin wrote:

> A while back there was reference to taking hyperstereo from an airplane
> using a motordrive. I was wondering what a typical time between frames might
> be. Do you space them out, say a second apart, or do you just fire off a few
> frames in continuous mode? I'm using a Nikon FM/MD-12 which runs around
> 3fps, if that helps. I'd really like to try this the next time I fly.

Before I submit my comments to this post, let me introduce myself since I'm new
to the list.  My name is Roger and I live in a log cabin in the mountains in
Western Colorado.  I bought my first stereo camera (a Realist 3.5) in 1963 from
a pawn shop.  I've really enjoyed reading the posts for the last several days
and it's great finding such a knowledgable group that shares my passion for
stereo photography.

Now to the subject of hyperstereo from aircraft...  The government takes a lot
of these pictures.  They use a high resolution camera mounted in the belly of
the plane.  The US Geological Survey uses them for generating topographic maps
and the Forest Service uses them for making timber counts.  I used to buy them
and carry them on backpacking trips.  I'd free-view them and could often glean
details about the terrain that weren't apparent from the topographic maps.  The
photos I have use a very wide stereo base--about a third of the total span of
the photo.  This gives exaggerated stereo, but is quite impressive.  These
pictures were taken, of course, with the camera pointed straight down.  I've
never experimented with taking my own from a commercial airliner, but I would
think that one would want to wait at least several seconds between shots.
Assume that you're flying at 30,000 feet and going about 700 feet per second
(about 500 MPH).  Different lenses would give different picture widths, but
assume that you can see about 30,000 feet on the ground.  To have a third of the
picture go buy would take about 14 seconds, but this would give the exaggerated
stereo effect I mentioned.  I'd think around 5 seconds would be a good starting
point.

Now, I have a question.  I recently purchases a TDC 716A projector on eBay.
Everything seems fine except for one very serious problem.  If I get one lens in
focus, the other one isn't.  I could probably tear into it and find out if there
is a way internally to adust the focus of the lenses independently, but one of
you out there probably could save me some grief.  HELP!!!

Roger