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Panoramic Vision

Panoramic Vision
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First Published: Tue, Sep 15 2009. 08 56 PM IST

Updated: Tue, Sep 15 2009. 08 56 PM IST
Free software can work miracles when you’re stitching photos to make a panorama, but a few extra clicks in the field can still save many more in the digital darkroom.
I made my first panoramic picture when I was 14. It consisted of four photo prints showing a mountain range in the English Lake District, glued to a sheet of backing paper and overlapping in such a way that where I’d got the craggy skyline to match up, the walls and fields in the valley below disappeared into nothingness at the edge of each picture. Nevertheless, it expressed in visual form something of which I was incredibly proud: I’d just hiked all the way across those mountains.
A panorama can be a thing of rare beauty, capturing the full sweep of your eye’s beholding with a breadth and detail that not even the widest of wide-angle lenses can match. Even a relatively modest 8MP camera can piece together a panorama that’s as tall as an A4 sheet and as long as you want to make it.
Huggin’ Hugin
It’s much easier to explain the appeal of a good panorama than it is to actually create one. Or so I thought, until I discovered a brilliant free open-source program called Hugin ( www.hugin.sourceforge.net ). It offers endless opportunities to get geeky, but at its most basic, it’s an incredibly powerful and accurate panorama stitcher. Best of all is its ability to automatically detect and manipulate “control points”—distinct landmarks that occur in two overlapping images—which are the keys to performing the warps, and I don’t believe in babying software when I want to know if it’s going to solve my problem, so as soon as it was installed, I chucked Hugin a doozy—a 16-shot panorama of the Sydney Opera House, taken pointing up at a 30-degree angle.
This image drove me to the edge of madness when I tried to piece it together manually in Photoshop. The converging lines produced by the upward tilt made mapping one image to the next a nightmare.
By contrast, Hugin ingested the files in a cool 5 minutes, analysed them, warned me there was a low likelihood of producing a smooth match and after showing me the wealth of matching control points it had found, grimly got down to stitching. Meanwhile, I nicked off for half an hour and made dinner, leaving the computer fans whirring madly. When I returned, there was a magnificent finished panorama waiting for me—all 486MB of it. I was expecting to see a mess of conflicting lines, but to my delight, I opened an almost perfect amalgam of my 16 original pictures. All that remained to do was some light cropping to get rid of sawtooth patterns where the tops and bottoms of the images met, and to airbrush out one stray line.
Basic panorama technique
This is a whole topic in itself and one that panorama software programmers will try to tell you is obsolete in the light of their incredible creations. But just as you don’t stride across a six-lane highway without looking just because doctors can do blood transfusions, don’t neglect the value of doing things right from the beginning:
1. Set your camera’s exposure, white balance and focus to manual. This avoids exposure problems when one part of the scene is darker than the other.
2. Keep the camera as close as possible to horizontal and rotate around a point as close as possible to the middle of the lens. A tripod with a spirit level could be a big help.
3. Overlap your shots, but not too much. I’ve shot panoramas with an 80% overlap, but all this achieved was to overload my computer with identical files.
4. Natural distortion will cause the centre of the panorama to bulge towards you while the edges taper away. Position your points of interest accordingly.
David Stott is a photographer based in Australia.
Write to us at sharpshooter@livemint.com
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First Published: Tue, Sep 15 2009. 08 56 PM IST