Friday, May 2, 2008

Spherical panorama photography

I've recently become interested in taking 360° x 180° spherical panoramas.

These are pictures that can be rotated in any direction. (Zooming in and out is also permitted.)

Apple's free Quicktime player works well for this purpose.

I'm actually interested in both handheld and tripod-based setups.
This blog entry will just cover using a tripod.
(The handheld part will come later.)

Here are the components:
  • A tripod. I use an ultralightweight carbon fiber/magnesium Gitzo 1155T (relevant blog entry).
    Its compactness and light weight are big plusses for hiking. However, you can use any tripod.
  • A camera. I borrowed an Olympus E-510 DSLR from a friend. (Previous blog entry on the camera here.)
  • A offset rotating bracket that places the axis of rotation around the entrance pupil of the lens to avoid parallax. The panohead I bought was the Nodal Ninja 3 Mk II. $200.

Oh, I nearly forgot. I also bought an Olympus Digital Zuiko 8mm lens. $660. Weighs about 1lb. The most expensive component here.

But this allows one to cover 360° of rotation comfortably in just 6 shots.

Although the camera is level here, I tilt to point the lens down nearly 15° when shooting for better coverage.

Rotate and shoot every 60°.
Add one zenith shot (for the ceiling).
And zero or more nadir shots (for the floor).

That's a total of 7 shots minimum.

Some details:
  • You can get fancier and rotate the camera as well to get the longest side, i.e. the diagonal, vertical. As a result, some people can get away with 4 shots but that's for another time when I describe the handheld setup.
  • The number of nadir shots depends on how hard it is to patch the location of the tripod.
  • Shoot aperture priority (i.e. fixed aperture), let shutter speed fall where it may. Let stitching software normalize exposure.
  • Let autofocus do its job. A fisheye typically has a large depth of field. (I haven't measured this one.)

Good software exists for arranging and stitching the shots together.

I use autopano pro. Its virtue is that it's almost completely automated. (Some tricky cases will require manual intervention.)

It produces equirectangular projections of the sort shown above. To prepare the image for Quicktime Player, I run it through pano2vr, which maps the image onto the six sides of a cube that the player needs:

Since I'm currently spending time at an architecturally distinguished building, I thought that'd make a good subject for my first panorama project.

See my webpage here for the pictures.

Also see my more recent blog entry on panorama head setup.

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