September 01, 2005

Panoramic fun

Follow-up to Panoramic photos from Steve's blog

In the previous entry I gave a few rules for taking photographs for panoramas. Specifically:

  • Use a manual exposure to ensure exposure is even across the whole set.
  • Use a tripod to keep the point of view consistent and the horizon level.

Here's what happens if you don't follow the rules.
A panorama gone wrong!

This was taken on auto, and hand held. I obviously wasn't paying too much attention to keeping the camera level and look what autostitch has done to the waterline in an attempt to match everything up. You could water ski on that lake without a boat (reminds me of a joke about an Irish waterskier:-)

If you straighten up all the pieces first (some of them needed rotating by 3 degrees to get them level), then you get a much better result:

This looks a little better!

The waterline is much straighter now, but the exposure still varies a lot between segments. I could also manually tweak the exposure to match them all up before stitching them together to make it work even better.
(By the way, the ghostly child is the result of him moving between shots. I haven't got around to fixing that yet!!)

It is much better, though, to get it all right from the beginning. This one was taken with the camera on manual, and mounted on a tripod. The exposure is even across the whole panorama and the waterline is level. And no manual fiddling involved first:

A panorama of Loch Lomond, taken from Firkin Point on the West shore

The first one (in its two versions) was taken from Rowardennan Forest on the east shore of Loch Lomond, the second from Firkin Point on the west shore, both this last weekend. The mountain in the second one is Ben Lomond itself.

- 2 comments by 2 or more people Not publicly viewable

  1. John Rawnsley

    Even the third one is not that level. I've been trying to merge 3 photos of a room using autostitch and the walls always end up curved. It would be nice to be able to specify a line on each image which is to be joined up and kept straight. It is correctly joining up straight lines, but it is curving them to join without corners. Maybe it is using some kind of conformal map to do the matching. If you ignore the curvature it introduces then some of the blending has been really impressive.

    01 Sep 2005, 14:55

  2. Steve Rumsby

    You're right. When you turn on the grid in Photoshop you can see that the waterline still dips in the middle. I guess after looking at the previous two, it looks so much better that I assumed it must be straight:-)

    The website suggests that it is using a spherical projection, which could account for it, I suppose. The non-demo version (which doesn't exist as far as I can tell) supports cylindrical and planar projections. I guess a cylindrical projection is what I assumed it was doing.

    01 Sep 2005, 15:45

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