Tuesday, February 8, 2011
Supersized Panorama Stitching
Brandon Riza’s panoramas are crafted in the spirit of an Ansel Adams landscape. In each one, the mountains are larger than life, and the overall image is richly detailed and built from a series of high-resolution frames.
I shoot only RAW and with Picture Style set to Neutral (not Picture Style Faithful, as that will warm the image). Shooting this way strips out in-camera sharpening, contrast, gamma and saturation levels. Basically, the image is as true to reality as possible. That’s also why I never use neutral-density filters, nor do I currently use polarizers. The only filters on my lenses are UV haze filters, mostly for protecting my investments. I endeavor to shoot as accurate a representation as is possible under the current conditions.
Overlap, Overlap, Overlap
Shoot more than you think you need. I shoot most everything with the camera oriented horizontally because I’ve found that shooting vertically can give you some odd squashing in the rendered pano, depending on the projection-mapping type you choose in the software. Using a tripod just makes sense more times than not if your end goal is high quality. The ballhead I use has marked radians, though it’s not entirely necessary with Autopano stitching software because it does such a great job of calculating the stitch points. If you level your tripod and shoot in the proper degrees, you’ll get very predictable results and accurate stitches.
That said, I do sometimes shoot from the hip. I’ve come home with panos that would have been great had I not rushed the shots in such a way that I created holes in my pano—areas I didn’t shoot. This happens way more often with zoom shots, 200mm panos and the like, where even with the proper focusing screen pattern it’s easy to get lost in the visual swim and become confused about what you’ve already shot and where you should be picking up the next shot. It has happened to me with all my lenses when I’m handholding, too.
The best rule of thumb may be to shoot for one-third overlap, but that’s oversimplified. The wider your lens, the more distortion is being processed by the software. Very wide lenses are a tall order for stitching apps. With tighter shots (such as the 50mm on a full frame), there’s far less spatial distortion, which means you can get away with far less overlap and the calculation time is typically much faster and far less likely to exhibit stitching errors. With a 200mm pano, you’re essentially placing identical pixels on top of each other and blending them, and there’s very little parallax correction needed.
You also have to work quickly, without rushing. Clouds move, lighting and shadows change, and if it takes you eight minutes to shoot 60 frames for your pano, you now have to deal with odd lighting issues and misplaced ghost-clouds in your final comp. A vista can go from perfectly bathed in stark light to pure soft light bereft of shadow in far less time.
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