Gigapixel Multi-Row Panoramas Made Easy with Monopod Technique
Microsoft's HD View caused quite a stir last year, and rightly so. The MS Research team solved several issues that have hampered the wider adoption of panoramic imagery in a single and mature offering. The wide angle projection issues of QuickTime VR and other viewers were solved with an ingenious adaptive projection algorithm. Also, tone mapping correction (haze reduction) was introduced to deliver a truly immersive experience that invites exploration of gigapixel images and is also great for web masters seeking to improve the "stickiness of their sites". As Greg Downing observed, virtual reality photographs have to match or exceed the real world viewing experience to be a long-term success. With consumers increasingly spoiled by HD imagery all around them, the unique proposition of gigapixel panoramas becomes apparent, in delivering a unique, immersive experience where the viewer is in full control to explore the image.
Still, the creation of high-resolution and gigapixel images on the professional level involves either hugely expensive equipment, be it the camera and film material (http://gigapxl.org) or special rigs to hold and move the camera like PixOrb, the PanoMachine or the GigaBot to create multi-row mosaics which are then stitched with software.
So it would be desirable to have a technique that can be employed by everyone at low cost and with widely available equipment. This can only be achieved if a generic camera, generic lens and generic camera mount are used.
Last week I created my first HD panoramic image, of Chiang Mai, Thailand, using a technique that involves only an **ancient Digital SLR, a cheap and generic telephoto lens and a monopod **as hardware. Then I used a simple column-based (rather than row based as the robots do) up-and-down zigzag technique to create the images. Thanks to the stitching power of PTGui (I use version 7.5 Pro where control point generation was improved), the source images can be created with an easy, some might say haphazard technique and then stitched without much effort. This technique using cheap and light equipment brings the creation of high-resolution gigapixel imagery within easy reach of photography amateurs.
Here are the details:
- A digital SLR or camera with long telephoto lens, I use the now prehistoric (yet seminal) Canon EOS 300 D (Digital Rebel) with 6 MP.
- A somewhat sturdy monopod that comfortably puts the camera at eye level, I use a Manfrotto 679 which is solid, cheap and feels great.
- A lens with a long focal length, I use a use a Canon EF 75-300 (4.5-5.6), which is light and very affordable and has a fast auto-focus. It should be around 200 bucks or Euros in the US and Europe respectively.
Now simply employ an **up-and down zig-zag technique **moving the camera vertically with the help of the screen markings in the camera viewfinder. Be careful to use plenty of overlap in both vertical and horizontal directions so that the stitching software has it much easier later. Through the monopod you have an anchor point with the ground which fixes the horizontal position (pan) of your camera quite nicely while your moving vertically, always lining up the screen markings in the viewfinder.
The images can then be stitched with PTGui or another multi-row stitching program. I didn't have much luck with Windows Live Photo Gallery, but PTGui stitched the photos in the first attempt without any correction necessary (except for me setting the projection incorrectly which led to some slant, see below).
There was some greenery in the way in both images so I had the idea of using a lower resolution panorama as a "canvas" for the higher resolution image. This worked quite well using Photoshop layers but was very tedious and the processing took forever. So it's probably better to take more images to fill the frame, don't skimp and take only the interesting parts of a vista even when you get tired of taking so many photos. For the final rendering of the tiles, the HD View Photoshop plugin worked flawlessly.
The "higher-up" image of Chiang Mai has a severe (well, about 4.5 degrees, small but annoying) slant to the left side, which might be due to warping and the wrong projection used when stitching with PTGui. I should have straightened the panorama better before stitching which will be done shortly, hopefully with the new Canon 450 D (coming soon) and double the resolution of the current panorama.
To improve results, the source images could be created with
- HDR (high-dynamic range) using bracketing or capable cameras,
- higher-resolution (preferable to longer lens in terms of usability),
- higher quality lens,
- better weather with less haze.
The processing time largely depends on the machine used and with my old notebook I use as a stitching workstation and external USD-hard-drives it took a couple of days until the images were ready. With some practice it might go much quicker. PTGui used tens of gigabytes for the stitching and Photoshop even more. So be sure to have enough free space on your drives.
As with all panoramas, the better the source images, the easier the processing. Be extra careful not to introduce gaps between columns so don't get distracted by fellow tourists. And use plenty of overlap in all directions. Here's hoping that HD View will soon support even more platforms and browsers, to become the platform of choice for a unique image viewing experience. As a final note, this technique is to be called the "leaning monopod technique" as it involves a leaning movement and a monopod. Happy snapping!
Wooden Photo Frames: Discovered this website whilst googling for 'photo frames' - a bit irrelevant I know but really enjoyed your blog but I Thanks
Posted: 16 April 2008