Automated Panorama Stitching with AutoStitch
If you have an interest in panoramic photography, you may
know
that aficionados wax poetic about their calibrated tripod heads, and
passionately debate the finer points of yaw optimization and control
point placement. While these things have their place, they are an
impediment to making images, especially for a beginner. When I
encourage friends to try panoramic photography, I steer them away from
manual tools like the free, powerful interfaces based on
Helmut Dersch’s Panotools,
or commercial alternatives like Stitcher. Like
any self respecting pusher, I want them to get an easy first thrill,
and before they start investing in paraphernalia.
If you are like one of my friends, impressed by the idea of taking an
occasional panorama, say from the top of a mountain, but don’t want to
buy anything new, or even put much effort into learning new software,
there is hope. What you are looking for is an automated stitching
program. Combined with these handheld techniques, you
can expand
your horizons, generating beautiful images.
Calibrated
hardware makes the process fool proof so high
volume producers can
push out images with perfect stitches, but it costs a bundle. Manual
software allows a person
to recover from less than optimal conditions, but requires a pretty
steep learning curve. For the rest of us there are programs that will
automatically stitch handheld panoramas most of the time.
This article will hopefully give you some background on stitching
panoramas, and then walk you through stitching a handheld shot using
Autostitch, a free software demo for MS Windows.We will cover:
- Background on digital panoramic photography and Autostitch
- Stitching a panorama with Autostitch
- Results
1. Background
Information
Why you need stitching software
If you have ever wondered why putting a series of
photographs together is a problem in the first
place, try a
little experiment. Close one eye. Put a thumb in the air in front of
your face. (Or a finger, if your thumb is missing or
otherwise
indisposed.) Line it up with a more distant object, like a door
across the room. Swivel your head. The fact that
the nearby
object moves relative to the distant one is called parallax.
Basically, as you take that series of images, the objects in them move
around, based on their relationships to each other and the camera.
Stitching software models the images and camera, putting everything
back
into its relative place.
Autostitch
My first yearning to make a panorama came after our Hut-to-Hut mountain
bike trip. I had a couple of instances where I had taken a circle of
images, and I thought it would be great to put them together.
Though I had taped prints together on my wall, I had never
given much thought to creating a single image using digital photography.
Still, based on my experiences with those snapshots, I should have
lowered my expectations. Firing up Photoshop CS was no good, as I
didn’t have the patience to stretch the images into place.I downloaded
panotools, and Hugin, an excellent interface, but never quite got
myself to try it out. It just seemed too complicated. In browsing the
web I came across Autostitch.
Autostitch is a demo of technology developed by Matthew Brown
and David Lowe at the University of British Columbia. Research on computer
vision lead to an intelligent stitching algorithm. The software itself
is very basic, and expires periodically, forcing you to download a new,
current version. But it’s free, and a great way to see if
panoramas are in your blood. This technology is patented, and has been
licensed to several commercial panorama software companies:
Autopano Pro www.autopano.net (Windows, Mac, Linux)
Serif PanoramaPlus www.serif.com (Windows)
Calico www.kekus.com (Mac)
along with George Lucas’s Industrial Light and Magic. Venturing forth
from the Autostitch page, you will find information about Matt’s
current research, his vacation photos…. The software does not need
installation. Just download, unzip, and use it.