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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:

1. Background on digital panoramic photography and Autostitch
2. Stitching a panorama with Autostitch
3. 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.

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This article was written on Wednesday, October 3rd, 2007 and is filed under Mastering Skills. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.