All 4 entries tagged Panorama

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September 19, 2005

My first 360

360o panorama, that is. This was taken from the top of Thorpe Cloud in Dovedale on Saturday afternoon, and as usual it was put together with autostitch.
360 degree panorama taken from the top of Thorpe Cloud in Dovedale
(The link goes to a full resolution version stored elsewhere as it is much too big for Blogbuilder – beware, it is a 20MB image of over 40MP)

I broke my usual rules with this, taking all the shots handheld (I wasn't about to lug a tripod up there) and left the camera on auto (I was in a hurry), but the result is not too bad. Of course it suffers from the usual autostitch curved horizon, and you can see areas where the exposure varies a bit too much. There are 17 individual pictures stitched together for this shot.

Because it is a 360o pano, and because autostitch is completely automatic, I had no idea where it would start and stop. As it turns out, the first shot I took has ended up in the middle. That's where the "ghost" is – somebody who was standing on the peak when I took the first shot but who had gone by the time I got back there after taking all the others. I'll edit that out sometime.

Thorpe Cloud is 930' about sea level (GPS height) and about a 450' climb.

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.

July 12, 2005

Autostitch isn't perfect…

Autostitch has done a pretty spectacular job of stitching together everything I've thrown at it. Probably at least as good as I could manage by hand (before my patience ran out, that is). Until yesterday…

While out cycling yesterday evening I came across a really nice sunset. All I had with me was my camera phone, but I thought I'd take it anyway. I took the scene in four pieces, with lots of overlap, and threw them at autostitch when I got home. This was the result:

I thought nothing more of it until this afternoon, when it occured to me that this wasn't actually wide enough. I thought I'd taken more of the scene to the left. When I checked this evening, it turns out I had. Autostitch had only pasted together two of the pieces. What happened to the others?

Well, because I was using a phone camera, everything was on auto. The exposures were different enough for autostitch to be unable to match them. Havng the sun in the right-most piece had made the sky and foreground fairly dark. As I panned left, away from the sun, the auto exposure lightened everythig up. Putting in a bit of effort by hand, starting first by adjusting the levels to match the exposures more closely, making each piece progressively darker to the left, followed by a bit of blending at the seams, produces the image I was expecting to get from autostitch in the first place:

You can still see the joins, so obviously I need some more practice at blending the pieces together, but it isn't too bad. For the record the auto panorama function in Photoshop Elements did a terrible job – it really didn't like the mismatched exposures.

This just reinforces one of the rules for making good panoramas – where possible set the camera to manual exposure to get the same exposure for each piece.

June 30, 2005

Panoramic photos

This panorama (full resolution version) in my blog about the Gala Concert has caused a few people to ask about how it was produced. Basically it was put together from 7 or 8 individual shots, deliberately taken so that they overlap. I usually try to make the pictures overlap by at least 25% – up to a point, the more overlap the better.

Then I used autostitch to glue them together. Autostitch does what it says on the tin. Give it a collection of overlapping photos and it works out for itself which order they go in and how to paste them together. It doesn't do a perfect job. If you look at the top right of the Maths building, and especially the top right of Riley Court, you'll see some ghosting where the join isn't perfect (you'll need to look at the high resolution version to see this). But the end result is still pretty impressive for a fully automatic process, and touching up those imperfections is straightforward (so, why haven't I done it you ask:-)

I have another example produced with autostitch, taken of the National Mall in Washington DC from the tower at the top of the Old Post Office:

There's pano stitching functionality in Photoshop and Elements also. I haven't tried that yet. Does anybody know how good a job that does?

When setting out to deliberately take pictures for stiching together, there are some things to bear in mind:

  • Ideally you should pivot the camera around the optical centre of the lens. That's kind of hard to do, especially when you've got a zoom lens. The closest you can easily get is to use a tripod. As it happens, the Gala pano was not taken with the help of a tripod, so decent results are possible without. The Washington panorama was also taken hand-held.
  • Overlap the individual pieces by at least 25–30%.
  • If possible, use a manual exposure so that all the pieces of the pano have the same exposure.
  • If possible use manual focus to keep the focus consistent across the whole panorama.
  • Be careful of moving objects, or they might end up appearing more than once in the finished result!

When thinking about panoramas, I always used the think of mountains and open spaces as the major subjects, but this gala panorama has made me realise than the technique is more widely applicable. I'll be looking for other unusual opportunities to use it.

One thing I'd like to try sometime is to do a small scale version of the 2.5 Gigapixel photo, by stitching not just horizontally but also vertically, to create a very high resolution picture. I don't think I'll make 2GP, though! I just need to find a suitable subject…

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