You've seen those cool QuickTime VR movies on the Web
and you want to learn how it's done? Well, you've come to the right place. Internet
Brothers to the rescue again. I'll be talking about creating panoramic movies here,
the kind you can move from side to side up to 360° as if you're standing on the
spot where the panorama was captured, spinning around. There is another type of QTVR image, the object movie,
where you can spin an object around to view all sides. I'll leave that discussion for
another time. If you're not quite sure what I'm talking about, take a look at
my personal site. Note: the free © Apple QuickTime browser plug-in is
required. The first thing you need to do is find a nice spot to
take photos and create a panorama with your camera. I've discovered it works best if
you're on top of a multi-directional vista, or in the bottom of a valley or bowl. Think
of a sine curve. But be careful when you turn. I wouldn't want you to start out at the
top and end up at the bottom. It's hard on your camera. It is a good rule of thumb to have a 50% overlap from
one image to the next. In other words, take three photos to capture the width that
could actually be done with two. Panorama software uses the overlap to help blend the
two images together. The more overlap there is, the smoother the transition between
images and the more seamless they appear. By the way, did you know the phrase "rule
of thumb" is derived from an old English law that stated you couldn't beat your
wife with anything wider than your thumb? Another advantage of having a full 50% overlap
between images is if something happens to one of the photos, you can still salvage the
panorama — although it might be difficult to make it appear seamless. That said, my camera using a 35mm lens takes 18
vertical images to capture 360° with 50% overlap on each image. This would require
fewer images with a wider angle lens such as 20mm, and a larger number of images with
a narrower angle lens such as 55mm. You should shoot the images vertically, allowing
for a taller perspective in the finished product. You can shoot horizontally but you'll
end up with a vertically narrow scene. Using a tripod makes this whole process much easier.
Although it is possible to do without one,
I don't recommend it. Most tripods have markings at the point where
they rotate, helping to determine how many degrees the camera is pivoting with each
turn. If yours doesn't, there are several manufacturers including Kodak, Bogen and
Kaidan that make special panorama tripod heads for just this purpose. In addition to
having the very handy degree markings, these tripod heads are designed so your
camera rotates around a central axis, meaning the focal point of the lens remains
aligned from frame to frame. This is a significant detail only if you're
trying to achieve perfection, or are very close to your subject. Panorama tripod heads
make the job of taking the many photos for a panorama much easier, but they aren't
cheap. I suggest you experiment without it first to see if panorama photography is
really going to be your thing. Exposure is very important in creating a seamless
panorama. Modern auto-exposure cameras can actually create a problem in this respect.
As you're moving the camera from shot to shot, the auto-exposure will make an unintended
contrast adjustment based on how the light meter perceives the brightness of the scene.
For example, I had a recent problem with this when there was a big white alien in the
center of one of the images. The camera's light meter shortened the exposure time
significantly when it saw the alien, making that image much darker than the rest. If possible, use a camera that doesn't have auto
exposure and set the lens and shutter speed to achieve a happy medium based on the
average brightness of the scene. Always avoid shooting your panorama when there are
moving clouds directly overhead. If the clouds move and the sun shines on you or your
subject halfway through the process, the exposure will suddenly change, making for a
lousy panorama. Avoid photographing long, straight objects like a
freeway for your panorama. Because of the warping affect a camera lens has on an image
from edge to edge, particularly a wide angle lens, a straight line will look bent or
curved in the panorama. You don't want to give your audience vertigo; or do you? Later this week, I will conclude the article by
discussing digital panoramas from the computer perspective. So go on out and shoot up
the neighborhood, so to speak, then we'll see what develops together.
Digital Panoramas
13th of June 2000The Camera Side
Use a Tripod
Watch Your Exposure
net.weblogs.com
...an experiment in freeform discourse
There was a competition to swim from Santa Monica to Catalina doing only the
breaststroke, and the three women who entered the race were a brunette, a redhead and
a blonde.
After approximately 14 hours, the brunette staggered up on the shore
and was declared the fastest breaststroker. About 40 minutes later, the redhead crawled
up, declared the second place finisher.
Nearly 4 hours after that, the blonde
finally came ashore and promptly collapsed in front of the worried onlookers.
When the reporters asked why it took her so long to complete the race, she replied,
"I don't want to sound like a sore loser, but I think those two other girls were using
their arms."