Not something you can print and hang on the wall.

If you had told this photographer a while back that he would be creating three hundred and sixty degree virtual reality pictures with a computer and photo stitching software a year ago, chances are the response would have included a recommendation to visit the local loony bin for an extended stay.

What got me intrigued about the possibility of making a Virtual Reality picture was probably a combination of factors. I had long been fascinated by the Virtual Tours that realtors place on their web sites brokering homes. You click and then pry around some unsuspecting stranger’s home. Shades of James Stewart as the Peeping Tom in Hitchcock’s Rear Window. Later I came across 360 degree VR pictures on the web of landscapes and famous places like the Eiffel Tower and St. Peter’s Basilica and wondered in awe at this new technology for making pictures. I hesitate to call them movies as the viewer is in charge of what he looks at and in what detail. Hose the cursor this way and that with your mouse and you can look around the Sistine Chapel taking in all the details of Michaelangelo’s ceiling painting, or descend to the depths of the Seine at the foot of Notre Dame.

Simply stated, none of this was possible before the days of computers; once digital cameras became affordable anyone could do it. I’m not sure of this, but I believe the technology was invented and patented by Ipix a few years ago, offering true 360 degree views around a subject of choice. Doubtless before long we will have holographic television with the image floating in space and viewable from all angles.

Lots of smart people have worked around the patents to offer inexpensive alternatives to Ipix; meanwhile Ipix books $2mm of revenue a quarter from its great invention. Another cheer for American entrepreneurship.

The poor man’s approach, then, is to take a bunch of overlapping pictures around a horizontal cylinder (you turn the camera from shot to shot using a tripod head) then add one for the zenith (top) and nadir (base). The zenith can be done on the tripod by tilting the camera up ninety degrees; the nadir is taken hand held by removing the tripod and snapping the ground, trying to avoid your toes.

A bit (OK, lots) of research on the web showed that this is still very much a nascent technology when it comes to art photography. No one place really seemed to explain how to do things, but piecing them together and reading bulletin boards and chat rooms got me on the right path.

I thought that a fisheye lens of some sort was essential to making Virtual Reality pictures but it turns out that is far from the case. Any reasonably wide lens will do. The wider the lens the fewer pictures have to be taken to generate the 360 degree whole; for that matter, you do not have to go the whole hog and can simply generate flat wide panoramas for viewers to enjoy. However, as I am having such great fun with Canon’s full frame Fisheye lens I thought I might give the 360 degree rendition a shot in the interest of less work. Less work is always a good thing.

My earlier efforts with stitching flat pictures from my Rolleiflex together into panoramas were disappointing. I used Photoshop and really struggled to get things to line up. So I put the idea to the back of my mind a few years ago. Look at the following picture taken in 2003 and you can see the objectionable bowing out of our house front, not to mention the stitching.

The Atherton estate at dusk. From four pictures on a Rolleiflex 3.5F,
Kodak Portra, stitched in Photoshop CS.

Now the chaps who are really serious about VR photography think nothing of spending $600 on an expensive tripod bracket which allows the camera to be rotated around the nodal point of the lens, rather than around the axis of the tripod bush. The nodal point is the right way to go to minimize distortion. Well, I wasn’t about to blow that sort of coin on an experiment, and after sniffing around a software package or two concluded that as long as you held the camera at the same height when taking the multiple pictures for your VR composition, and didn’t tilt things too much, you stood a pretty decent chance of getting a good result.

What do you need to make VR panoramas?

A camera with a 50mm lens or wider which can be set to manual exposure. Film or digital, though film will be a lot of work.
A tripod or monopod, or a really steady hand and good eye.
Software to stitch the pictures together.
A viewer to allow playback on your computer.

For a camera I used the Canon EOS 5D with the 15mm full frame Canon fisheye lens, using my trusty Bogen/Manfrotto monopod and Leitz ball head to mount the camera at a constant height.

Pictures are taken with the camera oriented vertically to maximize height and minimize the size of the holes at the zenith and nadir of the sphere that have to be filled in. As the Canon full frame fisheye has an effective vertical angle of view of some 88.41 degrees (Canon says it’s 91.73 degrees but that’s incorrect for this use), six pictures will nicely complete a circle with substantial overlap, making stitching easier. From what I have read a circular fisheye needs only four pictures but I would guess that the edge aberrations are significantly worse than with a full frame one. Speculation on my part as I have not used a circular fisheye.

One other thing to remember before snapping the pictures is to switch off auto exposure (you want sky tones constant), switch off auto white balace if using a digital camera (much the same reason) and switch off autofocus. You want a small aperture with maximum depth of field for this to work. Don’t ask…. Exposure has to be determined so as to accommodate the brightest and darkest parts of the scene where details are required. Not as easy as it sounds. I measured both and averaged. Finally, switch off the auto-rotate feature in your camera or you will spend time later turning each picture through ninety degrees – the stitching application does not support auto-rotate so the picture will come in horizontally, which is not what you want.

To keep things simple I set the camera on JPG, not wanting to convert a bunch of RAW images, and opted for the lowest quality setting to keep file sizes down. Each picture file was some 1.3mB in size.

Stepping outside the front door, 5D and fisheye on the monopod, I took ten pictures from one position, generously overlapping each with its predecessor. Ten, as I was not too confident about getting away with six – better too much overlap than none. Then I pointed the camera up and snapped the zenith picture – mercifully the Canon fisheye does not flare into the sun, so I could get away with this. Then taking the camera off the monopod, the nadir image was recorded by pointing the camera down.

The application I used to stitch these together is called PTMac. It costs $59 and runs on Apple Macs only. A downloadable database stores settings for lots and lots of cameras and lenses – here’s just a partial list:

Of course, wouldn’t you know it, the 5D + 15mm Canon EF fisheye is not in the list. After some messing about and help from chat boards, I determined the settings which are as follows – you can save them in a database of your own:

Getting these parameters right is key to a frustration-free path to generation of a VR picture.

Now PTMac is a tad clunky. Little is automated. Sort of like using logarithm tables in lieu of a scientific calculator. Mercifully, the current version (4.x) automates the generation of what the vendor calls ‘Control Points’ – points in areas of overlap between adjacent images which tells the program how to stitch things. It generates no fewer than ten control points for each pair of images – something that would take hours to do manually. When it comes to panorama generation, I save the file in the QuickTime Cubic VR[.mov] format. Control point generation and stitching took some five minutes on my 2 mHz PPC iMac G5 which is equipped with maximum RAM of 2 gB. That’s not too bad when you think of the insane number of calculations the application is going through – witness the loud fan noise from the iMac’s normally near silent self. That CPU is working hard.

To view the panorama you need Apple’s QuickTime which is available free here. There are versions for Mac OS X and for Windows.

I clicked on the generated file and got a somewhat distorted picture:

Zooming in fixed that, but I did not want the viewer to have to do that, so after some more hunting around on the internet, I came across Cubic Converter from an Australian company company named ClickHereDesign and after a quick trial I determined you could save a zoomed-in version which was much nicer to look at. Another $49 gave me a license to save the revised file in Quick Time format. Now things looked like this:

Cubic Converter also has the ability to allow the viewer to start looking at the picture while the file is still downloading, with increasing quality resulting as time passes. Instant gratification in the best tradition of The American Way.

Here is the result – my first Virtual Reality picture. The file is 1.5 mB in size, so a broadband connection is recommended. You can zoom in or out by using the Shift and Control keys or by clicking the + or – signs on the screen.

While some of the limbs of the tree need work, I’m pleased as punch at this first pass and much of the learning curve is behind me. Getting smooth gradation in the sky is no mean feat. Next I’ll get more serious using a tripod with a degree marked pan and tilt head (actually a felt tip pen and some ingenuity, before you get too excited) to get things just so. The $600 fancy tripod head can wait.