Attached is a panoramic photo taken from my roof. It is made up of 12 photos stitched together. I do not have any stitching software, so I stitched them manually using the freeware Paint.Net program. (BTW, thank you, Bitt, for steering me to that program when my MS Paint program died last year.) To view it you will need to download it, open it up in the viewer of your choice, zoom in until it fills the screen vertically and than scroll left and right. The panorama attached here is at 1/4 the resolution of the original photos because I didn't think anybody would appreciate a 60+ MB file (the bbs won't take one that size in any case) and besides that, my graphics editor won't let me create one that big.

There are a few weirdnesses with the panorama shot that I don't understand. For that, you will need to download the second photo (the smaller one) and open it up in some sort of graphics editor or viewer so that you can zoom in very close. Be aware that both pictures are large -- the Test Sample picture is about 700K, the Panorama shot is about 6 MB.

The Test Sample is two of the original high-res photos manually stitched together then cropped, with the picture on the right covering the picture on the left where they overlap. There is a white "X" on this picture denoting the exact location of the corner where the second picture was stitched to the first. Also, there are numbers on the picture from 1 through 8, indicating points of interest.

X: The corner of the join. Alignment in this immediate area is perfect, both horizontally and vertically. If you look very closely you will see a slight vertical discoloration about half a pixel wide where the two pictures are joined.

1: Only a little bit to the right, and the diagonal wire shows a serious discontinuity. If I align the wire perfectly, then many other elements become mismatched.

2: The drain pipe and the corner of the house are off by half a pixel, I understand why this occurs and that it can't be helped.

3: Each of the 11 pictures added to the original left-most picture "stair-stepped" after stitching, losing the bit off the bottom as shown here and extending the same amount higher than the one previous. My tripod has level indicators in two planes, and both were dead on. Perhaps because I was shooting at a downward angle this caused the stair stepping? I can't visualize what I needed to do to keep this from happening.

4: The roof line just beneath the "4" shows just the tiniest bit of misalignment, as does the corner of the mirador just above it. A fraction of a pixel.

5: This roofline shows a full three pixel-width jag that is not in the original (left-hand) picture.

6: This doesn't show any problem with the picture, I just thought it was interesting because to the left is the boat while it was sitting still when the left-side picture was taken, and by the time the right side picture was taken the boat had started up and is in motion. Where the boat's wake abruptly starts is the exact dividing line between the two pictures. Amusing, but not important.

7: Note the jag in the shoreline. We are now up to a seven pixel discrepancy in the alignment between the two pictures.

8: At the top of the picture, the right hand picture is a full 8 pixels higher than the left, even though at the bottom the alignment is perfect. Again, I cannot visualize what might be causing this.

So, does anyone understand this kind of photography well enough to explain to me the misalignments? How does real stitching software handle this sort of thing?

On the actual panorama shot, I aligned from the top, not the bottom as done with the high-res sample, because the misalignments are much more noticeable on the ridgetop and the shoreline than they are in the jumble of roofs and plants at the bottom.

For those who are interested (I don't know why they would be, but I love to talk about it )the 12 shots were taken with a Panasonic DMC-50Z camera, zoomed to 114 mm (35mm equivalency). Exposure was f-11 at 1/250 second, fixed (manual) so that the camera wouldn't try and compensate for light changes as it pointed more towards the sun while panning to the right. Focus was also set manually, locked in on the near shoreline (1/3 -- 2/3 rule, although at f-11 depth of field was pretty much five feet to infinity). ISO was 200. Photos were taken with the camera on a tripod, using the self-timer to avoid vibration.

All in all, I don't think it came out too badly for my first try at a panorama.

tanstaafl.

When you take a picture with a camera, the picture is distorted. Usually it's barrel distortion, so called because lines that were straight in real life bow outwards (that is, towards the edge of the photograph) at the middle, or pincushion distortion, which is the same thing but with the curve in the opposite direction. (Barrel distortion should really be called pillow distortion or something, as it happens in both/all axes, and barrels don't have rounded tops and bottoms. But that's neither here nor there, not to mention that examining the distortion in only two axes is a gross oversimplification to begin with.)

Since straight lines are no longer straight, but curved, and you're taking multiple pictures with different origins of the distortion, it's unlikely that things will line up properly, as the offset of an object in two different photographs is unlikely to be the same. Theoretically, I suppose, if you could precisely measure the rotation of your camera and make all of the photographs radially equidistant, you could line the photographs up so that objects would appear to be nondisjoint by making sure that the join happened at the exact middle point between the distortion origins. But that sounds impractical at best. Even then, though, you'd still have curvature of straight lines, so what was a straight horizontal line all the way around you in real life would appear scalloped in the photograph.

Commercial software deals with this by first dealing with the optical distortion so that things that were straight in real life are straight in the photograph. It's not perfect, but it's close.

There's more information on the Wikipedia page about Optical Distortion.

Have you tried the Microsoft product for this? I was under the impression that it did quite a good job.

i use autostitch:

http://cvlab.epfl.ch/~brown/autostitch/autostitch.html

the windows demo is fully functional, and doesn't expire.

Some of my samples:
http://picasaweb.google.com/lh/photo/otS5ehTviGHI3-mue4vz-g?feat=directlink
http://picasaweb.google.com/lh/photo/v-bfq_ucr_rPYz9flic5pQ?feat=directlink
http://picasaweb.google.com/lh/photo/bUY44waUXthIuG7ILh32hg?feat=directlink
http://picasaweb.google.com/lh/photo/pv1B72u6q2vxeVT1QySi1Q?feat=directlink

Autostitch for me as well - even though I have the Canon product which came with my EOS 450D. For most things Autostitch works better.

quick 'n' dirty example - Whale!

Probably have loads more on my picasa page, but needing to work...

You post things like this to gloat over the rest of us poor folks stuck looking at cube walls all day, don't you?

The answers to your questions are basically what Bitt said -- lens curvature. Some stitching software will correct for that before stitching. Another possible factor (especially for 3) is that the tripod mount socket on the camera isn't centered perfectly on the nodal point of the camera, so your rotation isn't just a rotation, it's a rotation and a shift. The way stitching software gets around something like the discoloration mentioned in X is to blend images where they overlap, rather than just abutting them at the edges, or doing a simple overlay.

Yeah, I keep going through different panorama stitching products as incremental improvements get made in the tech.

For extra hair-pulling fun, try combining panorama with HDR. An acquaintance did a photography project on this, taking four 360 panoramas, each in HDR, of a specific landmark at four different times of day. The resulting photos were spectacular. But the amount of work required was mind boggling.

The tripod socket is properly centered, as is the socket on the bottom of the camera.

However, I think I have a clue as to what happened. See the two attached photos, the first with the tripod facing due West, the second after panning the tripod around so it faced due East. To take these photos I had the tripod on a perfectly level tile floor, and the level indicator built into the tripod said it was straight. I confirmed that the center post of the tripod was vertical with another level.

tanstaafl.

Interesting. I'll have to try it out. I didn't know MS had a free stitcher.

I've tried it a couple times, and I think it does a fantastic job considering it's free.

I tried both the Autostitch program and the Microsoft program. Autostitch has more configuration options, Microsoft has a much simpler, user-friendly interface. Autostitch stitched two pictures (out of a 12-picture set) that Microsoft wouldn't.

The most important thing I learned playing with both programs is that the key to successful panorama is this: the more overlap you have, the better your chances. When I was stitching manually, minimal overlap was what made it easy. With the stitching programs, 25-35% overlap seemed to work best. I end up taking and stitching 16 pictures where before I had just 12, but with large overlaps I don't have to be as careful framing each shot so the picture taking is actually faster, and of course the stitching process takes under a minute instead of more than an hour.

tanstaafl.

The next most important thing I learned is that there seems to be a limit to the maximum size of a *.jpg file.

As soon as I reached about 64 MB, I cold no longer save as a *.jpg, but had to go to *.tif instead.

Is there such a limit?

tanstaafl.

No, there isn't. At least it's not 64MB. There may be a limit imposed by the software you're using, but it's not inherent in the image format. Usually software limits are with regards to a particular dimension of the image buffer in memory and measured in pixels though. Or total number of pixels in an image. Photoshop and Lightroom both have limits and at one point they weren't very hard to hit. Not sure where they're at today.

A 64MB JPEG is probably going to produce a TIFF many times larger (in file size) than that.



I don't know of any camera where the tripod socket is located anywhere close to the correct location for rotation. They may be centered horizontally at the center of the lens and maybe even at the focal plane, but the camera will potentially need to be rotated about a point forward of the front edge of its body, along its lens somewhere. The focal plane is not the correct place to rotate about. The front-to-back distance depends on focal length, so on a zoom lens it will also change depending on how you have your lens set.

The best bet is to use a pano head, such as the very nice and very well priced (compared to everything else) Nodal Ninja 3.

The stitching program I've always wanted to use, but still haven't, is AutoPano Pro. It can do horizontal, vertical, H+V, full 360 (in any direction) plus HDR. Perfect for cranking out those gigapixel shots.

Speaking of gigapixel, there's also the online software from GigaPan along with their motorized mounts to really make things relatively hands-free. They even have a model that can now deal with full-sized SLR bodies.

Did anyone see the Sony tv ad for their new panoramic tech.

One takes the still camera and scans the horizon with it - much like panning with a video camera. All this is processed in camera to produce the full panorama.