PanoTools:
RE: Need help stitching my helicopter panorama!
Edward Fink 2005-Jun-08 18:37:40
Well, I got another chance at the helicopter panorama on Monday,
but so far I haven't had any better luck stitching than last week.
The helicopter company decided not give a discount for retakes -
it cost the same $500 per hour as the first time, so I STRONGLY
emphasized to the pilot AGAIN the need to maintain position.
We went with what we thought was the easiest, simplest way:
having the pilot pirouette in position while I sat behind him and leaned
out as far as I could, shooting continuously around the circle. We went
with Bernhard's suggestion to try and rotate as fast as possible, hoping
I could finish a set before he drifted too far.
We didn't move as much as last week, but we moved off center -
it looks our circle covered about a one block radius. So far I haven't
got a good stitch out of it.
Out of desperation I finally used one of the photos as a map,
and I drew arrows showing our location, and the direction the camera was
facing. I made each arrow a separate Photoshop layer and named it the
same as the image name so I can use the map to select what images to
try.
That really helped a lot to understand our movement, and by
stacking up the different passes on top of each other I was able to find
some places where a shot from the second pass better matches something
on the first pass, and vice versa.
Unfortunately, I found at least a couple of places where I had
three of the compass points (4 shots with my D70/Sigma 8mm) fairly close
together, but then the shot for the last compass point was two blocks
away. I haven't yet tried to stitch some of the new combinations that
I've found because of the map, but that's the next step.
It took many hours to create the map. The hardest part for me,
without any flying experience, was looking at the images and trying to
figure out EXACTLY what the helicopter is over. Sometimes I thought I
was looking at the west side of a building, but when I looked again
later, I realized that it was just the shadow, and not the actual side
of the building, meaning I was really at least slightly east of the
building instead of west.
The taller the building, the more perspective clues, but our
wide circle went over several parking lots and small buildings that make
it a lot harder to judge exactly where we were.
Anyway, I just thought I'd pass that info along while I continue
trying to stitch different combinations of the pictures. If anyone
wants to see the flattened version of my map with all the location
arrows to show how much the drift was, they're at:
http://new-eden.com/temp/MapLowPasses.jpg
http://new-eden.com/temp/MapHighPasses.jpg
We really want the lower altitude (2500') shots, be we tried
some at a higher altitude too, thinking that would give me more slack
even if the pilot drifted. No such luck so far.
(The arrow point is the estimated helicopter position, the direction is
the camera direction. The really long arrows on the low altitude map
indicate nadir shots that don't extend to the horizon. It's faster to
draw a long arrow than change colors. The landing skids are so visible
in the nadirs that to use them you'd probably need a pair almost
perfectly 180 degree apart.)
Thanks again to everyone for the many tips and suggestions! If
the client doesn't dump me instead of the pilot, I may eventually have a
chance to try ALL your suggestions!
If I get another pilot, I'd like to show him everyone's
suggestions and see what he'd prefer.
Right now my tentative plan, if I get a third chance, is to try
and take more responsibility instead of leaving so much to the pilot,
and put the camera on a pole horizontally and (hopefully) rotate it
before the pilot can drift so far. (The way Willy shoots out over a
railing.) I've got a heavy duty, 12' telescoping light stand, and I'm
going to stick my camera on that and do some tests out the window. That
should also help me better deal with the landing skids. This time I
leaned as far out as my seat belt would let me, then I held my camera
out as far as the neck strap would allow, and I STILL got a lot of
landing skid in the pictures.
Ed
#removed#
http://www.new-eden.com/
No eternal reward will forgive us now for wasting the dawn.
-- Jim Morrison --
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