Stitching Time

By Brad Templeton Back to

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Many photographers, particularly landscape ones, have been exploring the new world of digital stitched panoramic photography. The prospect of unlimited resolution and field of view opens literal new vistas in your toolkit, and also can be the least expensive way to get a good quality wide angle shot.

In stitched photography, you shoot a series of overlapping shots covering a wide field of view. Then, special software blends the photographs to produce a seamless result. This allows shooting the complete sphere around you, a 360 degree view, or simply a sweeping panorama of any field of view you choose. The latter shots can produce dramatic giant prints, while full spheres and many 360 shots are often viewed on computer screens that allow the viewer to pan and zoom around the entire field. If you’ve ever seen a majestic landscape and felt you simply had to capture all of it, You’ll want to explore panoramic shooting.

The software for panoramics takes ordinary photos and, knowing the focal length, projects the typical rectilinear image back onto the sphere it really was. (Non-fish-eye lenses all work to keep straight lines straight on the print, even though they are not really straight to the eye). Once projected on a sphere they can be overlapped and blended smoothly.

Panorama Mounts

For best results, the camera is rotated around a special point in your lens known as the exit pupil or “no parallax point”− often incorrectly called the nodal point. If you spin around anything but the NPP, frames can’t perfectly overlap on foreground objects due to parallax. Many companies sell panoramic mounts that help rotate your camera precisely. Many also have “clickstops” that make it easy to move the camera by the right angle each time. These mounts range from inexpensive plastic assemblies like the $99 Panosaurus to others such as the GigaPan Epic Pro Robotic Camera Mount at just under $900.

The special mounts allow full sphere panorama shooting. For shots that only need a single horizontal row (which means most landscapes and skylines) you can get by with much less, in fact a simple rail on your existing tripod head that spins around the correct point in the middle of your lens does the job. The process to find that point is documented with any mount you buy.

Software

The good news is that panoramic software is very good, and you can often shoot panoramas without too much focus on the NPP, even hand-held, as long as there isn’t much in the near foreground.

Many digital cameras come with a free panoramastitching program.These vary in quality and many will need you to use a proper mount, or require a fair bit of work if you didn’t. If you get serious, or want to go hand-held, I recommend the package AutoPanoPro 2.5, which sells for 99 Euros. APP features a tool known as the SIFT algorithm which is able to very quickly find the overlap among hand-held images and generate excellent blends.

In fact, you can even consider stitching software as an alternative to an expensive wide angle lens. High quality normal lenses are very sharp and very inexpensive, but a good wide angle is costly. If your subject allows it, you can shoot a quick overlap with a normal lens (even by hand) and stitch the wide angle view. You still get the shallower depth of field of the longer lens, and this may not work with close foreground objects or large amounts of motion in your scene.

The latest versions of Photoshop Creative Suite (CS3 and later) also have good photo stitching tools. Photoshop is costly, and I would not purchase it just for the stitching, but if you already own it, explore this capability. Another worthwhile package for single-row panoramas is the $79 Panorama Factory. Much slower and more work than APP, it offers the useful ability to draw the blending region by hand, which turns out to be important in scenes with many moving objects.

People’s Square

Making the Photograph

Panoramic shooting requires a spot with a wide view. A few trees may not block a normal shot but could make a panorama difficult. Find the one spot that has the truly sweeping scene you seek, and set up your mount. For your first efforts, I recommend avoiding near foreground objects.

With every photograph, light is the most important thing. With sweeping panoramas, you’ll find the light is very different in one direction from another. Indeed in a 360 degree shot taken in the golden hour, one shot will be directly into the sun while the other side has it behind. Many panoramic programs will take shots of different exposures and combine them, but I strongly recommend you shoot the entire panorama with the same focus, exposure and white balance settings. You can use gradient filters in your photo-editing program to adjust the intensity curves in the different regions of your panorama.

If people, clouds or vehicles are moving, shoot quickly. If you’re not careful you may find that a moving object was tracked by your shooting and appears in several frames in a row. While this is amusing at first, a professional job will avoid duplicated people. Sometimes rather than shooting quickly, work slowly to allow things to completely move out of your shooting zone. In fact, you can generate artificially-empty scenes by asking the people to move out of the zone you are photographing. Clouds won’t obey you and if shadows are changing you must work quickly.

You always want to make a photograph interesting. One option in stitched photography, if the light is not changing quickly, is blending shots from different times. For example, you can shoot all the frames to cover a scene and then notice something animated in the scene. Shoot it at just the right time, replacing the old more boring shot from the earlier sequence. For example, I once shot Old Faithful this way. You can’t shoot the whole 360 during a single spurt of the geyser, but I was able to shoot most of the shot at another time but made sure I used a frame of the water at maximum height. You may consider this a bit of a cheat, but it’s a scene that really existed.

I have set a custom mode setting on my Canon DSLR. It’s set for manual exposure of “sunny/16” with autofocus moved to a different button, sunshine white balance, a fixed ISO and a long poweroff timeout. I usually have to tweak the exposure, and I focus once with the AF button and shoot a nice even panorama.

Shooting at night is challenging for panoramas. You may have to take dozens of exposures, and if even one is wrong (you get some blur) it may ruin your panorama. Unlike single shots, which you can check and take again, doing it for 30 shots is a chore. You need a sturdy mount and a cable release is strongly advised. Frames of pure blackness can’t be blended with other frames by the software. As you get more experienced, you will be able to handle more, including night shots and close foreground shots, even hand-held.

Blending

AutoPanoPro 2.5 is by far the easiest and fastest tool, though it sometimes fails and manual adjustment is needed. It also features a “Smartblend” approach that attempts to deal with things like moving objects. A simplistic blend will create ghost objects when something moves, or even objects cut in half if the blend region is short. The smartblend tries to do the blend over zones with nothing moving, but it doesn’t always succeed. When this happens APP lets you hand edit your source images to erase the moving objects and tell it not to blend over them.

Display

Because you can blend together huge numbers of photographs, including multiple rows of long-lens shots, people are blending truly huge images with billions, in some cases close to 100 billion pixels. Even modest panorama efforts will result in photos with 50 to 100 million pixels. Some are so large that you can’t really even print them at full resolution unless you have a giant wall and a lot of money. These are only viewed in pan-zoom viewers, such as krpano and at the gigapan web site.

Viewers are good, but I like to print select images, and print them very big. It’s truly amazing to see an image 20′ long that’s tack-sharp even if you put your nose up to it. You can easily shoot with more resolution than the human eye could see sitting where your camera was, and reproduce the experience of being there for those who see your photo. Printing like this is not always inexpensive. Most commercial printing houses have large format printers which can print 44″ or 60″ high by as long as you want. Prices typically will be $7 to $10 per square foot. I have often used a site named bigphotohelp.com which prints for $3.50 per square foot up to 96″ long. Today I have my own 24″ wide printer that allows me to print for around $1/square foot in ink and paper. My walls  are covered with “like being there” photographs. It can also be a challenge working with photographs that are gigabytes in size. You’ll want a fast multi-core computer and lots of memory. Indeed, I recommend running a 64 bit operating system so you can make use of 8GB or 16GB now that such memory has become inexpensive. It will help the stitching (though the best programs do it all from disk and keep memory usage down) but also your other manipulations.

Get your gear ready and when one of those amazing clear days comes, head out when the light is good and try to capture more than you ever have before.

Resources: Websites: Canon.com; kolor.com; gigapan.org; gregwired. com; panoramafactory.com; krpano.com; bigphotohelp.com


About the Author

Brad Templeton
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Brad Templeton founded ClariNet Communications Corp (the world’s first “dot-com”). He is a Director (and was Chairman 2000-2010) of the Electronic Frontier Foundation (EFF), the leading cyberspace civil rights foundation, and a popular photographer at Burning Man. He is currently working on software plans for robotic cars. www.templetons.com