|Not the original image for this post, but made the same way. (in fact its twice as large)
I haven't made any in a while, but decided to try something new after I saw this.
With the Paris Example at 26 gigapixels, my 32 megapixels pale in comparison. It was more just dipping my feet in the water of multiple exposure composites.
How did I do it?
Six shots across the scene, and three layers of shots high. With my camera in horizontal, or landscape orientation. I used a Canon70-200 f/4L-USM on my EOS50D body on sRAW1 (or 7megapixel). Focal length at 70mm throughout the images. This image made from eighteen 7MP photos at 70mm, works out to be approximately 32 megapixels in the end and produces an image like a 28mm lens would (by my guess, no calculations here).
What are some important things to consider when you are going to try to make a large panorama?
Your computer may challenge you, as mine did. I only produced a file successfully after my 4th attempt. The quality of your original photos may challenge you, and the scene you are shooting may challenge you.
Computer Troubles: I had made three attempts to produce a file before I came out with one in the end. 4GB of RAM on my 3 year old mac-book was struggling to produce a finished file after the repositioning and blending of layers. My photo-merging program was unable to merge everything properly itself, so I used the interactive layout to help it along. If you have level photos and evenly exposed, you shouldn't have a problem here. Three quarters of the way through the process, file closes, losing all the work with a warning "Start up disk almost full". The final time I needed nearly 10GB of free space on the hard disk. After checking the size of the raw panorama (including layer masks, and positioning) it was about 600MB. No wonder it had trouble saving.
Quality of Photos: It is best to consciously focus on taking proper panorama shots when you are at the location, and is virtual impossible to produce a file without doing a number of things right when the camera is in your hands. Tripod - Must have, your camera needs to sit still in one place, be consistently level all the time, and move smoothly when rotated. If your camera is not level, the horizon will be at different locations across your photos. Exposure - you need to keep an even exposure throughout. Set your camera to manual and choose an appropriate exposure. The darkest shadows of your image should have still a slight detail, and the highlights should not be blown out. If your scene has too large of a dynamic range then you will need to choose to sacrifice some shadows, or some highlights.
The Scene: Clouds, water, and foliage in the wind, will not sit still for you while you take your photos. So you need to act fast. Since you are trying to show one moment in time in an image, it will look very strange if you can identify one object in two or more locations because it was moving in the time of your photos. If you look closely on my panorama you can see not all the waves match up, nor does it 'make sense' for some to be seen where they are.
This was an earlier attempt. Twelve exposures from the top of Knox Mountain in Kelowna. If you divide the picture into 4 pieces lengthwise, I had 3 images of bracketed exposures for each of those pieces. I used a super-wide angle, EF-S10-22mm @ 10mm. The dynamic range in this scene was very high, so by making 4 HDR images, and in turn, stitching those together, all the shadows and highlights appear to be more balanced.
[I had a minor catastrophe and broke a lot of links to my images for this blog, and I have replaced some, but without others, some paragraphs make me sound like I'm talking about things that don't exist - my apologies!]